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Sick sinus syndrome

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Sick sinus syndrome

Definition:

Sick sinus syndrome is a collection of heart rhythm disorders that include:

• Sinus bradycardia (slow heart rates due to a slowing of your heart's own natural pacemaker)
• Tachycardias (fast heart rates)
• Bradycardia-tachycardia (alternating slow and fast heart rhythms)

Alternative Names:
Bradycardia-tachycardia syndrome; Sinus node dysfunction

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Causes, incidence, and risk factors:

Overall, sick sinus syndrome is relatively uncommon. Among the various forms of sick sinus syndrome, sinus bradycardia occurs more often than the other types.

Tachycardias that arise from the upper chambers of the heart (atrial fibrillation, atrial flutter/tachycardia, and supraventricular tachycardia) are also common forms. Typically, a period of elevated heart rates is followed by very slow heart rates when the tachycardia ends.

Abnormal heart rhythms are often worsened by medications such as digitalis, calcium channel blockers, beta-blockers, and anti-arrhythmics. Disorders that cause scarring, degeneration, or damage to the conduction system of the heart can cause sick sinus syndrome.

Sick sinus syndrome usually occurs in people older than 50, where the cause is often a non-specific, scar-like degeneration of the heart's conduction system.

In children, a common cause of sick sinus syndrome is heart surgery, especially to the atria (upper chambers).

Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may be associated with sick sinus syndrome, although those diseases may have nothing to do with the syndrome.

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