ANTEROGRADE CONDUCTION TO HIS BUNDLE DURING RIGHT VENTRICULAR OVERDRIVE PACING IN DIFFERENTIATING NARROW COMPLEX TACHYCARDIA; A COMPARATIVE STUDY WITH ESTABLISHED ELECTROPHYSIOLOGIC MANEUVERS

Abstract

Narrow complex tachycardias are usually of supra-ventricular origin. Proper recognition and diagnosis of these tachycardias is of clinical importance, particularly as catheter ablation now offers a definitive cure in most forms of SVTs. At electrophysiology study, differentiation is usually between AVNRT, AVRT due to a concealed accessory pathway and atrial tachycardia. Entrainment is an important pacing maneuver that can be used to identify reentry as a tachycardia mechanism and define the components of the reentrant circuit. Differentiation between AVNRT and accessory pathway mediated AVRT is challenging, even during electrophysiology testing. It is quite important when the arrhythmia is resistant to treatment and catheter ablation is considered. Likewise, discrimination between atrial tachycardia and other SVTs, during EP procedures, is quite important if ablation is to be performed. Multiple maneuvers and measurements have been proposed to differentiate between common types of supraventricular tachycardia. The present study was performed to assess the value of commonly used right ventricular pacing maneuvers to differentiate various types of narrow complex tachycardias; namely AVNRT, AVRT and AT. The present work is a prospective study that was conducted on ninety consecutive patients with narrow complex supraventricular tachycardia presenting to the electrophysiology group in Ain Shams University hospitals for electrophysiological study and ablation, in the period between September 2015 and March 2016. Selected patients were subjected to thorough history taking and clinical examination. ECG, with or without Holter examination, was done for all patients. Thereafter, all patients underwent electro physiologic studies in the electrophysiology labs of Ain Shams University Hospitals. The study population comprised 54 patients with AVNRT, 33 patients with AVRT and 3 patients with AT. AVNRT patients were older than AVRT patients with a trend towards female predilection. No significant difference was found in heart rate during tachycardia between these two patient groups. Atrial response upon cessation of right ventricular pacing associated with 1:1 VA conduction during tachycardia ha