Sinus bradycardia

Sinus bradycardia in adults is defined as a sinus rhythm rate below 60 beats per minute. It can be observed in healthy adults, athletes, the elderly, and during sleep. Other causes include increased intracranial pressure, hyperkalemia, hypothyroidism, hypothermia, and medications such as digitalis, beta-blockers, reserpine, guanethidine, and methyldopa, which may also induce bradycardia. Patients with organic heart disease may also present with sinus bradycardia, such as in coronary artery disease, acute myocardial infarction, myocarditis, cardiomyopathy, and sick sinus syndrome.