What is sick sinus syndrome?

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.

Sick sinus syndrome is a relatively uncommon condition, occurring in about 0.2% of the population. However, it is an important problem because it can cause significant symptoms.

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. Medicines such as beta-blockers, calcium channel blockers, and digoxin can make this condition worse by slowing the heart rate further or by causing heart block.

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). People with this syndrome often complain of intermittent palpitations (caused by either fast or slow arrhythmias) and lightheadedness. Also, if their heart rates become too slow or too fast, people may actually pass out (syncope). Occasionally this arrhythmia may cause chest pain or shortness of breath, especially if the person has other forms of heart disease.

Treatment of tachy-brady syndrome requires control of both the fast and slow heart rates. Treatment depends on the specific arrhythmia that occurs but usually involves the placement of a pacemaker to prevent the heart from beating too slow and the use of various medicines to prevent the heart from beating too fast.

Often medicines are needed to prevent the heart from beating too fast; however, these medicines may aggravate the slow arrhythmias and make symptoms even worse. A permanent pacemaker is often required to prevent the heart from beating too slow.

People who have both sick sinus syndrome and atrial fibrillation have an increased risk of stroke. Because of this risk, some people with both conditions should be placed on blood thinners.

Last Updated: June 18, 2009

related physicians

related services

Bon Secours International| Sisters of Bon Secours USA| Bon Secours Health System

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Privacy Policy. How this information was developed to help you make better health decisions.

© 1995-2010 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.