Heart Valve Surgery
What are heart valves?
Heart valves are flaps of inside lining of heart chambers. They are strategically located between the heart chambers. They open and close with each heart beat thus allowing blood to flow in forward direction. When valves do not work well, blood either leaks back into the chamber where it has just left or has difficulty flowing through it. In either condition the efficiency of heart function is limited; in turn your body does not get adequate blood circulation.
Your heart has four valves:
- Aortic Valve
- Mitral Valve
- Tricuspid Valve
- Pulmonary Valve
Even though each valve is an independent unit in it self, damage to one valve can over-burden the functioning of other valves, and in some situations make them dysfunctional.
Causes of valve damage
Valve tissue is thin, pliable but tough and resilient. It can withstand the rigorous demands of physical activity for the life of a person. However, there are certain conditions that can damage the valves, most commonly the following:
- Congenital valve disease. A structural abnormality a person is born with. Depending upon the magnitude of defect the valve may need correction early in life or can come to the attention of physicians later in life.
- Degenerative valve disease. Damage that has resulted from wear and tear. Just like your joints that develop arthritis with age, your valves can develop degenerative disease. The degenerative process makes the valves less pliable, stiff and, in extreme situations, replaces the whole valve with calcium.
- Myxomatous valve disease. A condition resulting from weak valve tissue. The valve becomes too pliable and results in leakage.
- Infection. Rheumatic heart disease and endocarditis are the two main conditions that results from infection.
Symptoms of valve disease
Efficient heart function is the result of strong heart muscle and well functioning valves that allow blood to move forward. When the valves are damaged your heart’s ability to pump the blood is impaired. Depending on the severity and duration of damage the symptoms could range from vague and subtle to life-threatening. Most common symptoms are:
- Fatigue. This is by far the most common symptom. When the body and its essential organs do not get enough blood, especially upon exertion, you will feel fatigue. This lack of energy is subtle and frequently attributed to age, generalized deconditioning, lack of motivation or even depression. It is important that you discuss this with your doctor.
- Shortness of breath at rest or with physical activity. If your heart cannot adequately pump blood to all body tissue you will have difficulty catching your breath and consequently limit your activity.
- Palpitations. Damaged valves can stretch heart chambers or make heart muscle develop scars. In either situation the rhythmic beating of heart can be replaced with irregular beating. You may develop a racing heart or feel extra beats inside your chest. A common condition associated with valve abnormalities is atrial fibrillation. A life threatening situation called ventricular fibrillation can also result from scarred heart muscle.
- Swollen feet, ankles and weight gain. Insufficient circulation can leave behind excess fluid to be accumulated in your ankles, feet or belly. You could feel heavy in your legs and tire easily. Fluid in belly can make you feel bloated and decrease your appetite.
- Fainting. The inability of your heart to adjust to sudden changes in body position can result in sudden loss of consciousness.
- Chest discomfort. Fullness or tightness in chest, especially with exercise, is a sign of heart in distress.
How is valve disease diagnosed?
- Physical exam. If the valve problem is congenital (i.e. you are born with it) you may already know that you have a heart murmur that your physician has been hearing at each exam and following for any change. More commonly a valve problem is detected at routine physical exam or during a visit to the physician’s office for evaluation of symptoms related any of the symptoms noted above. A heart murmur is a sound generated from turbulence of blood as it passes through defective valve.
- Echocardiogram. This is a test where ultrasound technology is used to provide still and moving images of the heart and the flow of blood. This is the most reliable test for the evaluation of valve function. It is a noninvasive and painless procedure.
- Transesophageal echocardiogram (TEE). This is similar to a regular echocardiogram, except that the pictures of heart are taken with an ultrasound probe placed at the end of an endoscope. This procedure requires the passage of the probe into your swallowing tube (esophagus) while you are under sedation. We rely on TEE to provide vivid, detailed pictures of valve structure. Both regular and transesophageal echocardiogram studies will be performed on you if you need valve surgery.
- Heart catheterization (coronary angiography). If your valve is damaged so much that you need surgery, you may be asked to undergo heart catheterization prior to valve surgery. This is a procedure where a small tube is threaded from the major artery in your groin up through the aorta and into the coronary arteries and the chambers of the heart. Direct pressure is measured inside heart chambers and coronary arteries are examined for the presence blockages. If your coronary arteries have any blockages you many need additional by-pass procedure during your valve surgery.
When is the valve surgery necessary?
Noticing a heart murmur or seeing a defective valve on echocardiogram is not a reason in itself to warrant heart surgery. The need for surgery depends on several factors such as the type of valve disease, the severity of the damage, your age and your medical history.
As a general rule you may need valve surgery if one or more of the following is present:
- The valve dysfunction is impairing your heart’s ability to effectively pump blood during rest or exercise
- The valve impairment is causing structural damage to your heart such as chamber weakening or enlargement
- The leak across the valve is severe, even with out you feeling any symptoms. This is particularly true of the mitral valve.
Your family doctor and cardiologist will assess your valve condition and send you to a surgeon for further evaluation.
Repair or Replace?
Not all defective valves need to be replaced at surgery. As a general rule your surgeon will attempt to repair and preserve your own valve as the first option, as there are advantages to having your own valve left in place. Of the four valves, mitral and tricuspid valves are more amenable to repair, compared to aortic or pulmonary valves. Most often the probability of repairing the valve can be determined before the surgery. Sometimes, however, this decision can be reached only during surgery when the valve can be directly visualized.
If the valve surgery warrants replacement, there are two main groups to choose from.
- Mechanical valves. Artificially made vales from pyrolite carbon, a light but strong and durable material.
- Advantages: This valve is strong and does not yield to wear and tear of use. It lasts for the duration of person’s life and rarely needs repeat surgery.
- Disadvantages. Since the valve is constructed out of an artificial material it has a tendency to form blood clots on its surface. Blood clots are dangerous both to the valve and to different body organs to which the clots can migrate, resulting in stroke, limb loss or even death. To prevent the blood clot formation, you will need the blood thinning medication Coumadin (warfarin) for life. Using a blood thinner requires the diligence of taking medication on time and frequent visits with your doctor to monitor the blood thinning levels. Your chance of being hospitalized for a bleeding complication is less than 2% per year of therapy. Coumadin is also known to cause birth defects and needs to be used in caution in patients of child bearing age. Despite these concerns, Coumadin is a very safe medication that has been successfully used for decades
- Tissue valves. As the name suggest these valves are made of natural tissue very often obtained from either cows or pigs. These valves can also be obtained as a donated body part from a deceased individual (this particular type of tissue graft is called a homograft). Tissue valves are soft, pliable and are subjected to wear and tear of use.
- Advantages. Since the material is natural tissue there is decreased tendency to form blood clots and blood thinning medication is generally not necessary. This valve is most suitable for women of child bearing age, patients who are at increased risk of bleeding and will not be able to take blood thinner, and patients over the age of 65.
- Disadvantages. The material these valves are made of is soft and has a tendency to wear out over time. These valves have been in use for over 20 years and it appears that, on average, a tissue valve can last from 10 to 15 years. When the valve fails, repeat surgery is needed.
The recommendations for replacement valve are clearer for patients who are less than 50 years old or over 65 years old. Younger patients benefit from mechanical valve as they will outlive the tissue valve. For patients between the ages of 50 and 65 years, the choice of replacement valve depend on several factors, including personal choice, longevity in family, previous heart surgery and associated medical conditions.