Sick sinus syndrome - a case report of paroxysmal supraventricular tachycardia due to atrioventricular node re-entry

Abstract

Sick sinus syndrome encompasses a variety of EKG manifestations consisting of atrial bradyarrhythmias and tachyarrhythmias, alternating bradyarrhythmias and tachyarrhythmias as in tachycardia-bradycardia syndrome. Supraventricular tachyarrhythmias that can occur include atrial flutter, atrial fibrillation, atrial tachycardia and paroxysmal supraventricular tachycardia, although there is no direct causal relation between paroxysmal supraventricular tachycardia and sinus node disease. Atrioventricular node re-entry is a common cause of paroxysmal supraventricular tachycardia episodes. We present the case of a 70 year old female, hospitalized for atypical chest pain and dizziness when walking. The EKG on admission showed sinus bradyarrhythmia, anterior fascicular block, atrial and ventricular extrasystoles. During the hospitalization the patient presented an episode of palpitations, narrow complex tachycardia being registered on the EKG, with no response to the Valsalva maneuver or intravenous beta blocker. The tachyarrhythmia ceased spontaneously after one hour. 24 hour Holter EKG was performed and confirmed sinus node dysfunction. The electrophysiological study identified paroxysmal supraventricular tachycardia due to atrioventricular nodal re-entrant tachycardia, which was successfully treated by ablating the slow intranodal pathway. Therefore, in a case of sick sinus syndrome when the patient’s symptoms cannot be attributed to the bradycardia, but to the tachyarrythmic episodes, it is often most efficient to treat the patient's paroxysmal supraventricular tachycardia by radiofrequency ablation, rather than using cardiac pacing.