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Topic Overview

Sick sinus syndrome is the name given to a group of arrhythmias that occur because the normal pacemaker of the heart (the sinus node) does not work properly. Sick sinus syndrome is also called sinus node dysfunction.

For more information on other types of sinus node problems, see Types of Bradycardia.

What causes it?

Sick sinus syndrome can occur for various reasons. It most commonly results from the effect of age on the sinus node. As we get older, scarring of the sinus node can occur and, in some people, it can be so severe that it causes this syndrome.

What happens?

Various irregular heart rates (arrhythmias) or combinations of arrhythmias can occur in this condition. People with this syndrome can have slow arrhythmias or a combination of fast and slow arrhythmias. These include:

• Periods of time when the sinus node does not fire at all (sinus pauses) and other areas of the heart take over and cause the heart to beat.
• Prolonged periods of time when the heart rate is spontaneously very slow and does not increase as it should with activity (persistent sinus bradycardia).
• Periods of fast arrhythmias (supraventricular tachycardias), especially atrial fibrillation or atrial flutter, alternating with periods of very slow heart rates ("tachy-brady" syndrome).

Treatment of sick sinus syndrome depends on the type of rhythm problem. Treatment typically is a pacemaker, and sometimes medicines is used too.

Tachy-brady syndrome

In tachy-brady syndrome, also called tachycardia-bradycardia syndrome, the heart sometimes beats too quickly (tachy) and sometimes beats too slowly (brady). This abnormal heart rhythm problem is often seen in people who have been diagnosed with atrial fibrillation. It can occur when the heart's natural pacemaker is damaged.

• Risk of complications? Yes. You may have symptoms such as palpitations and lightheadedness. You might pass out. You might have a higher risk of stroke.
• Treatment. Treatment may include a pacemaker to prevent the heart from beating too slow. Medicines might be used to prevent the heart from beating too fast. Blood-thinning medicines are used to help prevent a stroke.