Sick sinus syndrome are a group of heart rhythm problems arrise due to problems with the sinus node, such as: in case of  Sick sinus syndrome , heartbeat rate is too slow, some times called sinus bradycardia. The heartbeat pauses or stops, called sinus pauses/sinus arrest. Normally, the heartbeat starts in an area in the top chambers of the heart (atria). This area is the heart's pacemaker. It is called the sinoatrial node, sinus node or SA node. Its role is to keep the heart beat steady and regular.  Sick sinus syndrome is a group of heart rhythm problems 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 age 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, but not rare. It is the most common reason people need to have an artificial pacemaker implanted. Sinus bradycardia occurs more often than the other types of the condition. Tachycardias (rapid heart rhythms) that start in the upper chambers of the heart may be part of the syndrome. These include atrial fibrillation, atrial flutter, atrial tachycardia. A period of fast heart rates is often followed by very slow heart rates. Some medicines can make abnormal heart rhythms worse. These include digitalis, calcium channel blockers, beta-blockers, and antiarrhythmics.