Termination of Ventricular Tachycardia by Transvenous Cardioversion

Abstract

Transthoracic shocks using relatively low energy, for example, less than 40 joules, often can terminate organized sustained ventricular tachycardia. However, transthoracic shocks with these energy levels are painful and not tolerated by the awake patient. Previous investigations by Mirowski et al (1) demonstrated that ventricular fibrillation could be terminated in humans with an implantable defibrillator. We hypothesized that shocks applied directly to the myocardium via a catheter electrode might terminate sustained ventricular tachycardia with even lower energy levels than those used transthoracically or those necessary for internal defibrillation. These well-tolerated shocks would enable cardioversion in the awake alert patient. This report details the development of such a system.