The sick sinus syndrome A study of its cases

Abstract

Fifteen patients with features of sick sinus syndrome are reported. Their manifestations varied from severe sinus bradycardia, sinoatrial block, and arrest, to paroxysmal supraventricular tachyarrhythmias, reflecting the underlying unstable sinoatrial node. The rhythm can be bradycardic, tachycardic, or mixed. Thyrotoxicosis tops the list of aetiological factors, others being ischaemic heart disease, drug-induced, subarachnoid haemorrhage, cardiomyopathies, and myocarditis. Syncope, usually due to prolonged sinoatrial arrest, was the presenting feature in half of the cases, and some 70 per cent of patients showed radiological evidence of cardiomegaly, though clinical cardiac failure was uncommon. Therapeutic responses to vagolytic and sympathomimetic agents were variable, particularly discouraging in patients with mixed bradycardia and tachycardia. Cardiac pacing may be life-saving in some cases.