Prolonged Episode of Asystole in a Patient with Sick Sinus Syndrome: Case Report

Abstract

Background: Sick sinus syndrome (SSS), also known as sinus node dysfunction (SND), is a disorder of the sinoatrial (SA) node caused by impaired pacemaker function and impulse transmission producing a constellation of abnormal rhythms. Sick Sinus Syndrome is a highly relevant clinical entity, being responsible for the implantation of the majority of electronic pacemakers worldwide. Case Summary: An 80-year-old patient with a recent diagnosis of atrial fibrillation after a syncopal attack, presented to our clinic complaining of new onset lightheadedness. Following a pre-syncopal attack in our clinic, extensive analysis was performed and showed no underlying causes for the light headedness. A 24-hour Holter monitoring was performed and demonstrated signs of sick sinus syndrome with unusually prolonged sinus pauses without an escape rhythm. Urgent correction with permanent dual chamber pacemaker was performed with an uneventful postoperative recovery. Discussion: In sick sinus syndrome, cessation of sinus rhythm (sinus arrest) for short intervals without an escape rhythm, or longer periods of pause with replacement of sinus rhythm by an atrial or junctional rhythm are commonly seen. However, recurrent prolonged ventricular asystolic episodes are infrequently encountered and an extremely rare cause of syncope. It is known that triggers like anaesthesia, certain drugs or epilepsy can unmask sinus node dysfunction, which then manifests as significant atrial dysrhythmias and “rarely” asystole but long asystolic episodes of such duration were never reported in the absence of any trigger in patients with sick sinus syndrome. Permanent pacemaker placement is the recommended treatment for sick sinus syndrome.