Isolated palpitations and ventricular pre-excitation

Abstract

A 27-year-old male was referred for further assessment after being evaluated by his general practitioner for isolated palpitations. A twelve-lead electrocardiogram was performed in which sinus rhythm with ventricular pre-excitation were observed. Electrophysiologic study demonstrated the presence of a fasciculoventricular accessory pathway.

Keywords: accessory pathway; electrophysiology; tachycardia.

FIGURE 1

Twelve‐lead electrocardiogram of the patient. The trace shows normal sinus rhythm at a rate of 90 beats/min with a PR interval of 120 ms and small delta wave positive in inferior leads and negative in precordial lead V1. An atrial premature complex conducted to the ventricle is also evident (fourth beat)

FIGURE 2

A, Electrocardiographic leads II, V1, and V4 and intracardiac recording from right atrium, His bundle, and right ventricular apex during atrial extrastimulus testing. B, Electrocardiographic leads II, V1, and V4 and intracardiac recording from right atrium, His bundle, and right ventricular apex during rapid atrial pacing. C, Ladder diagram explaining the phenomena observed in panel (B). Panel (A) shows the end of an atrial pacing train at 795 ms followed by the introduction of a single atrial extrastimulus coupled at 260 ms During the train, ventricular pre‐excitation is observed, with an HV interval of 0 ms (normal between 35 and 55 ms), and after the atrial extrastimulus, conduction through the atrioventricular node is prolonged very significantly (AH interval), pre‐excitation continues to the same degree, and a single atrioventricular nodal echo beat occurs as well. For the last beat shown in the figure, which is a sinus beat, the degree of pre‐excitation is also the same (HV interval of 0 ms). In panel (B), during a 360 ms atrial pacing train, Mobitz I‐type second‐degree atrioventricular block is observed due to block in the atrioventricular node, with persistence of the same degree of pre‐excitation in all conducted beats regardless of PR interval length. In panel (C), the presence of the fasciculoventricular pathway inserted to the His‐Purkinje system distally to the His bundle is represented, which allows the ventricle to be slightly pre‐excited for the conducted beats. A, atrium; AVN, atrioventricular node; FV, fasciculoventricular accessory pathway; H, His signal; HBE, His bundle electrogram; HPS, His‐Purkinje system; HV, His‐to‐ventricle interval; RA, right atrium; RVA, right ventricular apex; V, ventricle