Sick Sinus Syndrome (SSS)
Sinus dysfunction; Sinoatrial node disease
Sick sinus syndrome is a group of abnormal heart rhythms (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's primary pacemaker. Tachycardia-bradycardia syndrome is a variant of sick sinus syndrome in which the arrhythmia alternates between slow and fast heart rates. Tachycardia-bradycardia syndrome is often associated with ischemic heart diseaseand heart valve disease. Disorders that cause scarring, degeneration, or damage to the sinoatrial node can cause sick sinus syndrome, including sarcoidosis, amyloidosis, hemochromatosis, Chagas' disease, and cardiomyopathies.