The electrocardiographic, clinical, and electrophysiologic spectrum of idiopathic monomorphic ventricular tachycardia

Abstract

Ventricular tachycardia (VT) can occur in the structurally normal heart [1–30]. In patients with VT the arrhythmia has been classified ‘idiopathic’ or ‘primary electrical disease’. Two main types of idiopathic monomorphic VT have been described in the literature. One shows a right bundle branch configuration and a left or superior axis [10, 11, 15–29], and an-other shows a left bundle block configuration during tachycardia with a normal or right axis [1–14]. Tachycardias with a right bundle branch configuration and left or superior axis can very often be terminated with intravenously administered verapamil and are easily inducible by programmed stimulation [16, 19, 20, 22, 24, 28]. On the other hand, the second group of tachycardias are the most common and seem to originate in the right ventricular outflow tract or superior part of the interventricular septum. They may be difficult to induce by programmed electrical stimulation and do not respond to calcium channel blockers [4, 7, 12, 13, 30]. To our knowledge, no attempts have been made to compare the clinical and electrophysiologic characteristics of both groups and to define the features of patients who have other QRS configurations of monomorphic VT (left bundle branch block with a left or superior axis and right bundle branch block with a normal or inferior axis). The purpose of this study was to compare the clinical and electrophysiologic characteristics of four groups of patients with monomorphic idiopathic VT as defined according to the ECG configuration.