Sick Sinus Syndrome

Abstract

The sick sinus syndrome describes a rather heterogeneous group of patients whose presenting symptoms are primarily cerebrovascular in nature (Stokes-Adams attacks, dizziness, and cerebrovascular accidents). The principal pathophysiological disturbance is "sinus node" dysfunction characterized by bradyarrhythmias (sinus bradycardia, sinoatrial block, sinus arrest) with or without associated tachyarrhythmias (tachycardia-bradycardia syndrome).¹ An interest in and an awareness of this syndrome is mandated by the frequency of these complaints. Historically, the first causal relationship delineated was between Stokes-Adams attacks and sinus bradycardia and sinoatrial block.^2-4 Later in 1954 Short⁵ described syncope in patients with alternating bradyarrhythmias and tachyarrhythmias. Lown⁶ actually coined the term "sick sinus" syndrome to describe a group of patients in whom, after electrical cardioversion, chaotic atrial activity, bradycardia, ectopic beats, and atrial and nodal tachycardia developed. Ferrer⁷ ultimately grouped these patients with diverse symptoms and dysrhythmias together under the general heading "sick sinus syndrome" in