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Sick sinus syndrome
Sick sinus syndrome is a group of heart rhythm disorders that include:
- Sinus bradycardia: This occurs when the natural pacemaker of the heart does not send out a signal telling the heart to beat often enough. The heart beat rate is slow.
- Sinus pauses or arrest: This occurs when the natural pacemaker of the heart stops sending out signals telling to heart to beat for periods of time.
People with these disorders may also have other abnormal heart rhythms, such as:
- Supraventricular tachycardia: This is a fast heart rate that starts in the upper chambers of the heart (atria).
- Bradycardia-tachycardia: This is a pattern of alternating slow and fast heart rhythms (sometimes called "tachy-brady syndrome").
Bradycardia-tachycardia syndrome; Sinus node dysfunction
Sick sinus syndrome most often occurs in people older than 50. It is often due to scar-like damage to electrical pathways in the heart muscle tissue.
In children, heart surgery on the upper chambers is a common cause of sick sinus syndrome.
Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may occur with sick sinus syndrome, although these diseases may have nothing to do with the syndrome.
Sick sinus syndrome is uncommon. Sinus bradycardia occurs more often than the other types of the condition.
Tachycardias that start in the upper chambers of the heart may be part of the syndrome. These include atrial fibrillation, atrial flutter, atrial tachycardia, and other types of fast heart rates. A period of fast heart rates is often followed by very slow heart rates immediately after the tachycardia ends.
Some medicines can make abnormal heart rhythms worse. These include digitalis, calcium channel blockers, beta-blockers, and anti-arrhythmics.
Most of the time, there are not symptoms.
Symptoms that do occur may mimic those of other disorders.
Symptoms may include:
Exams and Tests
The heart rate may be very slow at any time. Blood pressure may be normal or low.
Sick sinus syndrome may cause symptoms of heart failure to start or get worse. Sick sinus syndrome is diagnosed when the symptoms occur only during episodes of arrhythmia. However, this is often hard to prove.
An ECG may show abnormal heart rhythms related to this syndrome.
Holter monitoring is an effective tool for diagnosing sick sinus syndrome. It may pick up very slow heart rates and long pauses, along with episodes of atrial tachycardias. Other forms of long-term electrical monitoring may also be useful.
An intracardiac electrophysiology study (EPS) is a very specific test for this disorder. However, it is not often needed and may not confirm the diagnosis.
Exercise testing has not been shown to work well to detect the problem.
You may not need treatment if you do not have any symptoms. Your doctor will review the medicines you take to make sure they are not making your condition worse. Do not stop taking any of your medicines unless your doctor tells you to do so.
You may need a permanent implanted pacemaker if your symptoms are related to bradycardia (slow heart rate).
A fast heart rate (tachycardia) may be treated with medicine. Sometimes, a procedure called radiofrequency ablation is used to cure tachycardia.
In some cases, medicines used to control periods of fast heart rate are combined with use of a pacemaker, which guards against periods of slow heart rate.
The syndrome is progressive, which means it usually gets worse over time.
The long-term outlook is excellent for people who have a permanent pacemaker implanted.
- Decreased exercise capacity
- Fainting (syncope)
- Falls or injury caused by fainting
- Heart failure
- Poor heart pumping
When to Contact a Medical Professional
Call your health care provider if you have:
- Other symptoms of the condition
Keeping your heart healthy by eating a well-balanced diet and exercising can prevent many types of heart disease.
You may need to avoid some types of medicines. Many times, the condition is not preventable.
Olgin JE, Zipes DP. In: Specific arrhythmias: diagnosis and treatment. In: Bonow RO, Mann DL, Zipes DP, Libby P, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. St. Louis, MO: WB Saunders; 2011:chap. 39.
Zimetbaum P. Cardiac arrhythmias with supraventricular origin. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 64.
Reviewed By: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.