Normally, the heartbeat starts in an area in the top chambers of the heart. This area is the heart's pacemaker. It may be called the sinoatrial node, sinus node or SA node. Sick sinus syndrome is a group of heart rhythm conditions due to problems with the sinus node, such as:
- The heartbeat rate is too slow, called sinus bradycardia
- The heartbeat pauses or stops, called sinus pauses or sinus arrest
- Episodes of a fast heart rate
- Slow heart rhythms that alternate with fast heart rhythms, called bradycardia-tachycardia or "tachy-brady syndrome"
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 heart disease, high blood pressure and aortic and mitral valve diseases may occur with sick sinus syndrome. However, these diseases may have nothing to do with the syndrome.
Sick sinus syndrome is uncommon.
Some medicines can make abnormal heart rhythms worse. These include digitalis, calcium channel blockers, beta-blockers and antiarrhythmics.
Most of the time there are no symptoms.
Symptoms that do occur may mimic those of other disorders. These symptoms may include:
- Chest pain or angina
- Confusion or other changes in mental status
- Fainting or near-fainting
- Dizziness or lightheadedness
- Sensation of feeling the heart beat (palpitations)
- Shortness of breath, possibly only with physical activity like walking