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Coronary artery disease

MyHealth

Description:

An in-depth report on the causes, diagnosis, treatment, and prevention of coronary artery disease (CAD).



Alternative Names:

Angina; Atherosclerosis; Heart disease



Highlights:

Coronary Artery Disease

Coronary artery disease (CAD), also called heart disease, is a condition in which fatty deposits, called plaque, build up in the heart's arteries. These deposits cause arteries to become narrow and blocked, which restricts blood and oxygen flow to the heart muscle. CAD is the leading cause of death for both men and women in the U.S.

Risk Factors

The most important factors that increase the risk for CAD are:

  • Smoking
  • Unhealthy cholesterol and lipid levels
  • High blood pressure
  • Diabetes
  • Lack of exercise
  • Obesity
  • Advancing age

Symptoms

Angina is the primary symptom of CAD. Angina feels like gripping pain or pressure in the chest area.

  • Stable angina is predictable chest pain that lasts a few minutes or less and is usually relieved by rest or medication. It is often triggered by physical exertion or emotional stress.
  • Unstable angina is unpredictable chest pain and may occur at rest. When patients with stable angina have symptoms that are more severe or occur with less and less activity it is called unstable angina. It is a more serious condition than stable angina and can be a warning sign of a heart attack.

Some patients with CAD have few or no symptoms. Sometimes a heart attack may be the first sign that a person has CAD.

Treatment

Lifestyle changes (such as a healthy diet and regular physical activity) are essential for preventing and treating CAD.

Medications for preventing and treating CAD include aspirin, cholesterol-lowering drugs (statins), and high blood pressure medications (such as beta blockers, calcium channel blockers and ACE inhibitors). Some patients take nitrate drugs such as nitroglycerin or other medications (including some blood pressure medications) to treat angina.

Procedures may be needed to open a blocked or narrowed coronary artery and improve blood flow to the heart. These approaches are known as reperfusion therapy. Percutaneous coronary intervention (PCI), also called angioplasty (usually with stenting), uses a small balloon to open the blood vessel. Coronary artery bypass graft (CABG) is a more invasive procedure that is generally recommended for patients with multiple severe blockages. It uses grafts in the form of arteries or veins to reroute blood flow to the heart.

Heart Disease Guidelines

The American College of Cardiology, American Heart Association, and other professional organizations' guidelines recommend:

  • For patients with heart disease, controlling blood pressure and lipids is very important, as is the regular use of anti-platelet therapy (ideally aspirin).
  • Patients deciding between CABG and PCI should meet with an interdisciplinary medical team that includes both a cardiac surgeon and an interventional cardiologist. CABG is a more invasive procedure. But it may work better than PCI for certain patients, such as those with diabetes.
  • Cardiac rehabilitation is strongly recommended, especially for patients who have undergone bypass surgery. Patients who have had CAGB should also be screened for depression.
  • Sexual activity is safe for most patients with stable CAD. But patients with severe heart disease should abstain until their condition stabilizes.


Introduction:






Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.





Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.






Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.





Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.
Coronary artery disease






Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.





Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.






Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.





Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.




Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.



Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, results from a complex process known as atherosclerosis.

Click the icon to see an animation of coronary artery disease.

Atherosclerosis is the hardening and narrowing of the arteries caused by the build-up of plaque inside the arteries. (Plaque is the sticky substance made up of fat, cholesterol, calcium, and other substances found in the blood.) Cardiovascular diseases caused by atherosclerosis include CAD, heart attack, peripheral artery disease, and stroke.

In atherosclerosis, fatty deposits (plaques) of cholesterol and other cellular waste products build up in the inner linings of the heart's arteries. This causes blockage of arteries and prevents oxygen-rich blood from reaching the heart (ischemia). There are many steps in the process leading to atherosclerosis, some not fully understood.

Click the icon to see an image of atherosclerosis.

Cholesterol and Lipoproteins. The atherosclerosis process begins with cholesterol and sphere-shaped bodies called lipoproteins that transport cholesterol.

  • Cholesterol is a substance found in all animal cells and animal-based foods. It is critical for many functions. But under certain conditions cholesterol can be harmful.
  • The lipoproteins that transport cholesterol are referred to by their size. The most commonly known lipoproteins are low-density lipoproteins (LDL) and high density lipoproteins (HDL). LDL is often referred to as "bad" cholesterol. HDL is often called "good" cholesterol.
  • Triglycerides are another type of lipid (fat) that lipoproteins help circulate through the blood. High levels of triglycerides, like high levels of LDL, can increase the risk for heart disease.
Click the icon to see an image of a tear in the wall of an artery.

Oxidation. The damaging process called oxidation is an important trigger of atherosclerosis.

  • Oxidation is a chemical process in the body caused by the release of unstable particles known as free radicals. It is one of the normal processes in the body. But under certain conditions (such as exposure to cigarette smoke or other environment stresses) these free radicals are overproduced.
  • In excess amounts, free radicals can be very dangerous, causing damaging inflammation and even affecting genetic material in cells.
  • In heart disease, free radicals are released in artery linings where they oxidize low-density lipoproteins (LDL). The oxidized LDL is the basis for cholesterol build-up and damage on the artery walls, leading to heart disease.

Inflammatory Response. For the arteries to harden there must be a persistent reaction in the body that causes ongoing harm. This reaction is an immune process known as the inflammatory response.

Click the icon to see an image of inflammation.

Blockage in the Arteries. Eventually the calcified (hardened) arteries become narrower, a condition known as stenosis.

  • As this narrowing and hardening process continues, blood flow slows, preventing sufficient oxygen-rich blood from reaching the heart muscles. The supply can fall short of the demands of working muscle.
  • This oxygen deprivation is called ischemia. When it is severe enough in the coronary arteries, it causes injury to the tissues of the heart.
  • These narrow and stiff arteries not only slow down blood flow. They also become vulnerable to injury and clot formation, which is what usually triggers a heart attack.
Click the icon to see an image of a coronary artery blockage.

The End Result: Heart Attack. A heart attack can result in several ways from atherosclerosis:

  • Type 1 heart attack occurs when the plaque develops in fissures or tears. Blood platelets stick to the tears to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the blood clot severely or completely blocks blood flow to the heart muscle.
  • Type 2 heart attack, which is less common, develops from a problem with oxygen supply and demand. A heart attack can occur if the heart's oxygen demand increases to exceed the (usually narrowed) artery's ability to deliver oxygen-rich blood.
Click the icon to see an image of how atherosclerosis develops.

The external structures of the heart include the ventricles, atria, arteries, and veins. Arteries carry blood away from the heart while veins carry blood into the heart. In the following image, the vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide.

Click the icon to see an image of heart arteries.


Coronary artery disease


Risk Factors:

Coronary artery disease (CAD), also called heart disease or ischemic heart disease, is the leading cause of death in the United States. Over the past few decades, heart disease rates declined in both men and women as they quit smoking and improved dietary habits. However, this improvement has leveled off in recent years, most likely because of the dramatic increase in obesity in the U.S. and other industrialized nations.

Age

The risk of coronary artery disease (CAD) increases with age. Most people who die from heart disease are over the age of 65. However, many people younger than this are also at risk.

Gender

Men have a greater risk for CAD and are more likely to have heart attacks earlier in life than women. Women's risk for heart disease increases after menopause. Heart disease is the leading cause of death in both women and men.

Genetic Factors and Family History

Certain genetic factors increase the likelihood of developing significant risk factors, such as diabetes and high blood pressure. Heart disease tends to run in families. People whose parents or siblings developed heart disease at a younger age are more likely to develop it themselves.

Race and Ethnicity

African-Americans have the highest risk of heart disease, due in part due to higher rates of severe high blood pressure, diabetes, and obesity.

Click the icon to see an image of African-American heart disease risk.

Lifestyle Factors

Smoking. Smoking is the most important lifestyle risk factor for heart disease. Smoking can cause elevated blood pressure, worsen lipids, and make platelets very sticky, raising the risk of clots. Although heavy cigarette smokers are at greatest risk, people who smoke as few as three cigarettes a day are at increased risk for blood vessel abnormalities that endanger the heart. Regular exposure to secondhand smoke also increases the risk of heart disease in nonsmokers.

Alcohol. Moderate alcohol consumption (one or two drinks a day; 5 ounces wine, 12 ounces beer, or 1.5 ounces hard liquor is one drink) can help boost HDL "good" cholesterol levels. Alcohol may also prevent blood clots and inflammation. By contrast, heavy drinking harms the heart. In fact, heart disease is the leading cause of death in alcoholics.

Diet. Diet plays an important role in the health of the heart, especially in controlling dietary sources of cholesterol and restricting salt intake that contributes to high blood pressure.

Physical Inactivity. Exercise has a number of effects that benefit the heart and circulation, including improving cholesterol and lipids, lowering blood pressure and blood sugar levels, and improving weight control. People who are sedentary are almost twice as likely to suffer heart attacks as are people who exercise regularly.

Medical Conditions

Obesity and Metabolic Syndrome. Excess body fat, especially around the waist, is a significant risk factor for heart disease. Obesity also increases the risk for other conditions (such as high blood pressure and diabetes) that are associated with heart disease. Obesity is particularly hazardous when it is part of the metabolic syndrome, a pre-diabetic condition that is significantly associated with heart disease. This syndrome is diagnosed when at least three of the following are present:

  • Abdominal obesity (fat around the waist)
  • Low HDL ("good") cholesterol
  • High triglyceride levels
  • High blood pressure
  • Insulin resistance (diabetes or prediabetes)

There are numerous ways to control your weight and diet .

Unhealthy Cholesterol and Lipid Levels. Low-density lipoprotein (LDL) cholesterol is the "bad" cholesterol responsible for many heart problems. Triglycerides are another type of lipid (fat molecule) that can be bad for the heart. High-density lipoprotein (HDL) cholesterol is the "good" cholesterol that helps protect against heart disease. Doctors test for a "total cholesterol" profile that includes measurements for LDL, HDL, and triglycerides. The ratio of these lipids can affect heart disease risk.

Click the icon to see an image of a blood test.

High Blood Pressure. High blood pressure (hypertension) is associated with coronary artery disease. For an adult, a normal blood pressure reading is below 120/80 mm Hg. High blood pressure is generally considered to be a blood pressure reading greater than or equal to 140 mm Hg (systolic) or greater than or equal to 90 mm Hg (diastolic). Blood pressure readings in the prehypertension category (120 to 139 systolic or 80 to 89 diastolic) indicate an increased risk for developing hypertension.

Click the icon to see an image of hypertension.

Diabetes. Diabetes, especially for people whose blood sugar levels are not well controlled, significantly increases the risk of developing heart disease. In fact, heart disease and stroke are the leading causes of death in people with diabetes. People with diabetes, both type 1 (so-called "juvenile") and type 2 (so-called "adult onset") are also at risk for high blood pressure and unhealthy cholesterol levels, blood clotting problems, and impaired nerve function, all of which can damage the heart.

Peripheral Artery Disease. Peripheral artery disease (PAD) occurs when atherosclerosis affects the extremities, particularly the feet and legs. The major risk factors for heart disease and stroke are also the most important risk factors for PAD. (The combination of such conditions with PAD also produces more severe forms of heart or circulatory disease.) Even though signs of heart disease are often not evident in the majority of patients with PAD, most of these patients also have coronary artery disease.

Depression. Although people with heart disease may become depressed, this does not explain entirely the link between the two problems. Data suggest that depression itself may be a risk factor for heart disease as well as its increased severity. A number of studies indicate that depression has biologic effects on the heart, including blood clotting and heart rate. Guidelines recommend that patients who have undergone coronary artery bypass surgery or angioplasty (PCI) be screened for depression. Stress may also contribute to risk.

Risk Factors with Unclear Roles

Homocysteine and Vitamin B Deficiencies. Deficiencies in the B vitamins folate (known also as folic acid), B6, and B12 have been associated with a higher risk for heart disease in some studies. Such deficiencies produce higher blood levels of homocysteine, an amino acid that has been associated with a higher risk for heart disease, stroke, and heart failure.

However, while B vitamin supplements do help lower homocysteine levels, they appear to have no effect on heart disease outcomes, including preventing heart attack or stroke. Research indicates that homocysteine may be a marker for heart disease rather than a cause of it.

In general, there is little evidence supporting vitamin supplements for heart disease prevention. According to the United States Preventive Services Task Force, there is insufficient evidence that regular use of multivitamin supplements reduces the risk for heart disease. There is conclusive evidence that vitamin E supplements do not help protect against heart disease.

Click the icon to see an image of B vitamin supplementation. Click the icon to see another image of B vitamin supplementation.

C-Reactive Protein. C-reactive protein (CRP) is a product of the inflammatory process. It is not known if the protein plays any causal role or whether it is simply a marker for other factors in the disease process.

Lp(a). Lipoprotein-a, also called Lp(a) is a lipoprotein that is associated with coronary artery disease and stroke.

LP PLA2. Lipoprotein-associated phospholipase A2 (LP-PLA2) is a marker of vascular inflammation which is associated with heart disease and stroke.

C. pneumoniae and Other Infectious Organisms. Some microorganisms and viruses may possibly contribute to the inflammation and damage in arteries. The most interesting evidence to date suggests a potential role for Chlamydia (C.) pneumoniae (an atypical bacterial organism that causes mild pneumonia in young adults). C. pneumoniae is sometimes detected in plaques in the arteries of patients with heart disease. However, treatment with appropriate antibiotics has not been found to reduce the risk of future heart problems for patients infected with this organism.

Other studies suggest that cytomegalovirus (CMV), a common virus, may have similar effects. However, many people have been infected with these organisms, and no clear association has been found with any of these infections.

Sleep Apnea. Obstructive sleep apnea (OSA) is a common sleep disorder. It occurs when tissues in the upper airways come too close to each other during sleep, temporarily blocking the inflow of air. There is evidence that severe OSA is an independent risk factor that may cause or worsen a number of heart-related conditions. Patients with severe, untreated OSA are at increased risk for CAD, high blood pressure, stroke, and heart attack.

Periodontal Disease. Periodontal disease and heart disease are both inflammatory conditions that share common risk factors such as smoking and diabetes. According to the American Heart Association, more evidence is needed to establish a cause-and-effect relationship between gum disease and heart disease. Still, periodontists and cardiologists recommend that patients who have periodontal disease and at least one risk factor for heart disease should have a medical evaluation for heart problems. Patients who have CAD should have regular exams to check for signs of periodontal disease.



Symptoms:

Common symptoms of coronary artery disease (CAD) include:

  • Angina (chest pain)
  • Shortness of breath (particularly during physical exertion)
  • Rapid heartbeat

Sometimes patients with CAD have few or no symptoms until they have heart attack or heart failure.

Angina

Angina is a symptom, not a disease. It is the primary symptom of CAD and, in severe cases, of a heart attack. It is typically felt as chest pain and occurs as a consequence of a condition called myocardial ischemia. Ischemia results when the heart muscle does not get as much blood and oxygen as it needs for a given level of work. Angina is usually referred to as one of two states:

Click the icon to see an image of angina.
  • Stable Angina, which is predictable
  • Unstable Angina, which is new, less predictable, and a sign of a more serious condition

Angina can be mild, moderate, or severe. The intensity of the pain does not always relate to the severity of the medical problem. Some people might feel a crushing pain from mild ischemia. Others might feel only mild discomfort from severe ischemia.

Click the icon to see another image of angina.

Stable Angina and Chest Pain

Stable Angina. Stable angina is predictable chest pain. Although less serious than unstable angina, it can be extremely painful or uncomfortable. It is usually relieved by rest and responds to medical treatment (typically nitroglycerin). Any event that increases oxygen demand can cause an angina attack. Some typical triggers include:

  • Exercise
  • Cold weather
  • Emotional tension
  • Large meals

Angina attacks can happen at any time during the day. But more occur between 6 a.m. and noon.

  • Angina pain or discomfort is typically described by patients as fullness, tingling, squeezing, pressure, heavy, suffocating, or gripping. It is rarely described as stabbing or burning. Changing one's position or breathing in and out does not affect the pain.
  • A typical angina attack lasts minutes. If it is more fleeting or lasts for hours, it is probably not angina.
  • The pain is usually in the chest, under the breast bone. It often radiates to the neck, jaw, or left shoulder and arm. Less commonly, patients report symptoms that radiate to the right arm or back, or even to the upper abdomen.
  • Women, older people, and patients with diabetes are particularly likely to experience atypical symptoms that often involve discomfort in the abdomen, nausea, or unusual fatigue and weakness instead of chest pain.
  • Stable angina is usually predictably relieved by rest or by taking nitroglycerin under the tongue.

Other symptoms that may indicate angina or accompany the pain or pressure in the chest include:

  • Shortness of breath
  • Nausea, vomiting, and cold sweats
  • A feeling of indigestion or heartburn
  • Unexplained fatigue (more common in women)
  • Dizziness or lightheadedness
  • Palpitations

Unstable Angina and Acute Coronary Syndrome

Unstable angina is a much more serious situation and is often an intermediate stage between stable angina and a heart attack, in which an artery leading to the heart (a coronary artery) becomes sufficiently blocked so that the blood supply to the heart drops and the heart muscle dies. A patient is usually diagnosed with unstable angina under one or more of the following conditions:

  • Pain awakens a patient or occurs during rest.
  • A patient who has never experienced angina has severe or moderate pain during mild exertion (walking two level blocks or climbing one flight of stairs).
  • Stable angina has progressed in severity or occurs with less provocation, and medications are less effective in relieving its pain.
  • The patient suffers a fainting episode.

Unstable angina is usually discussed as part of a set of conditions called acute coronary syndromes (ACS). ACS also includes a condition called non ST-segment elevation myocardial infarction (NSTEMI) -- also referred to as non-Q wave myocardial infarction. With NSTEMI, blood tests indicate a developing heart attack . The third type of ACS is ST-segment elevation myocardial infarction (STEMI), during which one of the major heart arteries is completely blocked and full-thickness heart muscle damage may occur.

Other Types of Angina

Prinzmetal's Angina. This type of angina is caused by a spasm of a coronary artery. It almost always occurs when at rest. Irregular heartbeats are common. But the pain is generally relieved promptly with standard treatment (nitrate medications or calcium channel blockers).

Silent Ischemia. Some people with severe coronary artery disease do not have angina pain. This condition is known as silent ischemia, which may occur when the brain abnormally processes heart pain. Silent ischemia is a dangerous condition because patients have no warning signs of heart disease. Some studies suggest that people with silent ischemia have higher complication and mortality rates than those with angina pain.

Other Causes of Chest Pain or Discomfort

Chest pain is a very common symptom in the emergency room. But heart problems account for less than half of all chest pain episodes. There are many other causes of chest pain or discomfort, including:

  • Injured muscles
  • Arthritis
  • Heartburn
  • Asthma

Still, if you are experiencing chest pain, it is best to seek immediate medical attention.



Diagnosis:
ECG




Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 
Dye in coronary artery

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 



Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 
Dye in coronary artery

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 




Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 
Dye in coronary artery

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography, CT angiography is not as accurate in identifying who truly has coronary artery disease and who does not. However, when a patient’s CT angiogram is completely normal, it is very unlikely that they have significant blockages. CT techniques include electron beam computed tomography (EBCT) and multidetector computed tomography (MDCT), which use different technologies to generate images of the heart.

 Click the icon to see an image of a CT scan. 

Many tests are used to diagnose heart disease. The choices of which and how many tests to perform depend on the patient's risk factors, history of heart problems, and current symptoms. Usually the tests begin with the simplest and may progress to more complicated ones.

Routine Tests to Determine Risk for Heart Disease

Doctors routinely check for high blood pressure and unhealthy cholesterol levels in all older adults. In some cases, the doctor may test for levels of C-reactive protein (CRP), which is associated with increased inflammation in the body.

Other tests may also be ordered such as blood tests for Lp(a) and LP-PLA2, or imaging tests (coronary calcium or carotid intima-medial thickness measurement). Specific tests are also important in people who may have risk factors or symptoms of diabetes.

Electrocardiograms (ECGs)

An electrocardiogram (ECG) measures and records the electrical activity of the heart. However, up to half of people who suffer from angina or silent ischemia have normal ECG readings. The waves measured by the ECG correspond to when different parts of the heart contract and relax. Specific waves seen on an ECG are named with letters:

The electrocardiogram (ECG, EKG) is used extensively in the diagnosis of heart disease, from congenital heart disease in infants to myocardial infarction and myocarditis in adults. There are several different portions of an electrocardiogram.
  • P. The P wave is associated with the contractions of the atria (the two chambers that receive blood from outside the heart).
  • QRS. The QRS is a series of waves associated with ventricular contractions. (The ventricles are the two major pumping chambers in the heart.)
  • T and U. These waves follow the ventricular contractions.

The most important wave patterns in diagnosing and determining treatment for heart disease and heart attack are ST deviations and Q waves: 

  • A depressed or horizontal ST wave suggests some blockage and may indicate the presence of heart disease, even if there is no angina present.
  • ST elevations and Q waves are the most important wave patterns in diagnosing and determining treatment for a heart attack. They suggest that an artery to the heart is completely blocked, and that the full thickness of the heart muscle is at risk. However, ST segment elevations alone do not always mean the patient has a heart attack. Other factors are important in making a diagnosis.

Exercise Stress Test

Exercise stress test for evaluation of coronary artery disease may be performed in the following situations:

  • Patients with possible or probable angina, to help determine the likelihood of coronary artery disease being present
  • Patients who were previously stable who suddenly began having symptoms
  • Follow-up of patients with known heart disease, or following coronary bypass surgery or a percutaneous intervention
  • To determine a patient's functional capacity (how well the heart can respond when extra demand is needed)
  • Patients with certain types of heart rhythm disturbances
  • After a heart attack, either before leaving the hospital or soon afterward

Basic Procedure. A stress test (exercise tolerance test) monitors heart rhythms, blood pressure, and clinical status. It can tell how well the heart handles work and if parts of the heart have decreased blood supply. A typical stress test involves:

  • The patient walks on a treadmill or rides a stationary bicycle. Exercise continues until the heart is beating at least 85% of its maximum rate, until symptoms of heart trouble occur (changes in blood pressure, heart rhythm abnormalities, angina, and fatigue), or the patient simply wants to stop.
  • For patients who cannot exercise, the doctor may administer dobutamine, which is a drug that simulates the stress of exercise. In this case, some form of imaging is required.

An ECG is used to monitor heart rhythms during a stress test. (An echocardiogram or more advanced imaging technique may also be used to visualize the actions of the heart and blood flow.)

Interpreting Results. To accurately assess heart problems, varieties of factors are measured or monitored using the ECG and other tools during exercise. They include:

  • Exercise capacity. This is a measure of a person's capacity to reach certain metabolic rates.
  • ST waves on the ECG. Doctors specifically look for abnormalities in part of the wave tracing called an ST segment. A certain type of ST segment depression may suggest the presence of heart disease. However, gender, drugs, and other medical conditions can affect the ST segment.
  • Heart rate. This is how fast the heart rate goes during exercise and how quickly it returns to normal recovery. Based on age and other factors, everyone's heart rate should go up to a certain level during exercise. If it does not go up to the expected level, the patient is considered at risk for heart problems.
  • Changes in systolic blood pressure. Generally, the blood pressure will go up during exercise. If blood pressure drops or rises quickly this can be a sign of other problems.
  • Oxygen levels may also be measured.

Using these and other measures, doctors can determine risk fairly accurately, particularly for men with chronic stable angina. However, the test has limitations, and some are significant. In patients with suspected unstable angina, normal or low risk results may not be as accurate in predicting future risk of cardiac events.

Depending on the type of test and the population studied (young people or those with few risk factors and atypical symptoms) a significant proportion of patients will have false positive test results. In such cases, test results indicate abnormalities when there are no heart problems.

Echocardiograms

An echocardiogram is a noninvasive test that uses ultrasound images of the heart. This test is more expensive than an ECG-only stress test. But it can provide very valuable information, particularly in identifying whether there is damage to the heart muscle and the extent of heart muscle damage. An echocardiogram also provides other information about heart structure and function, such as the valves.

A stress echocardiogram may be performed to further evaluate abnormal findings from an exercise treadmill test or a routine echocardiogram. Examples include identifying exactly which part of the heart may be involved and quantifying how much muscle has been infected. It may be the first test done when an exercise treadmill test cannot be performed.

Radionuclide Imaging

Radionuclide procedures use imaging techniques and computer analyses to plot and detect the passage of radioactive tracers through the heart. Such tracing elements are given intravenously. Radionuclide imaging is useful for diagnosing and determining:

  • Severity of unstable angina when less expensive diagnostic approaches are unavailable or unreliable
  • Severity of chronic coronary artery disease
  • Success of surgeries for coronary artery disease.
  • Whether a heart attack has occurred

Myocardial Perfusion (Blood Flow) Imaging Test (also called the Thallium Stress Test). This radionuclide test is typically used with an exercise or chemical stress test to determine blood flow to the heart muscles. It is a reliable measure of severe heart events. It may be useful in determining the need for angiography.

First, a radioactive tracer (such as thallium, technetium, or sestamibi) is given through an IV while the patient is at rest. Then, a scan of the heart is done.  Sometime after this exercise/stress is begun, and about a minute before the patient is ready to stop exercising, the doctor administers a radioactive tracer into the intravenous line. Immediately afterward, the patient lies down for a second heart scan.

The images before and after exercise are compared. Sometimes delayed imaging is performed to see if areas of the heart may benefit from revascularization in an area of a prior heart attack.

Radionuclide Angiography. This test is a technique for evaluating the main pumping chambers of the heart (the ventricles). It uses an injected radioactive tracer and can be performed during exercise, at rest, or with use of stress-inducing drugs. It can help determine the function of the ventricles (left more commonly than the right) and is an alternative to echocardiograms in certain situations.

 Click the icon to see an image of the heart.   Click the icon to see an image of an MRI scan. 

Angiography

Angiography is an invasive test. It is used for patients who show strong evidence for severe obstruction on stress and other tests, for patients with severe typical symptoms, and for patients with acute coronary syndromes. It is required when there is a need to know the exact anatomy and disease present within the coronary arteries and is often followed by percutaneous coronary intervention (PCI, also called angioplasty and stenting).

In an angiography procedure:

  • A narrow tube is inserted into an artery, usually in the leg or arm, and then threaded up through the body to the coronary arteries.
  • A dye is injected into the tube, and an x-ray records the flow of dye through the arteries.
  • This process provides a map of the coronary circulation, revealing any blocked areas.
  • Once these blocked areas have been identified, PCI is sometimes performed.
 Click the icon to see an image of angiography. 

Magnetic Resonance Angiography (MRA). MRA is a newer noninvasive imaging technique that can provide three-dimensional images of the major arteries to the heart.

Computed Tomography

Computed tomography (CT) scans may be used to evaluate coronary artery disease.

Calcium Scoring CT Scans of the Heart. These scans are used to detect calcium deposits on the arterial walls. The presence of calcium correlates well with the presence of atherosclerosis of the heart. If the calcium score is very low, a patient is unlikely to have coronary artery disease. A higher calcium score may indicate an increased risk of current and future coronary artery disease. However, the presence of calcium does not necessarily signify narrowing of the arteries that would need further immediate evaluation or treatment.

CT Angiography. CT scans may also be used to visualize the coronary arteries. When compared to invasive angiography