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Sick sinus syndrome   

Overview | Symptoms | Treatment | Prevention

Alternative names:

Bradycardia-tachycardia syndrome

Definition:

A group of abnormal heartbeats (arrythmias) presumably caused by a malfunction of the sinus node, the heart's "natural" pacemaker.

Causes and Risks

Sick sinus syndrome is a relatively uncommon syndrome affecting approximately 3 out of 10,000 people. It can be manifested by many arrhythmias, including sinus arrest, sinus bradycardia (slow heart rate), sinus node exit block, and other similar bradycardias.

Tachycardias (fast heart rate) such as PSVT and atrial fibrillation/flutter may also be associated with sick sinus syndrome. Tachycardias of sick sinus syndrome are characterized by a long pause following the ending of the tachycardia.

Abnormal rhythms are often caused or worsened by medications such as digitalis, calcium channel blockers, beta-blockers, sympatholytic medications, and anti-arrhythmics. Disorders that cause scarring, degeneration, or damage to the conduction system can cause sick sinus syndrome, including sarcoidosis, amyloidosis, Chagas' disease, and cardiomyopathies.

Cardiac surgery, especially to the atria, is a common cause of sick sinus syndrome in children. Non-specific fibrotic (scar-like) degeneration of the conduction system (age-related) is often the cause.

Coronary artery disease, hypertension (high blood pressure), and aortic and mitral valve diseases may be associated with sick sinus syndrome, although this association may only be incidental.

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