Identification of ventricular tachycardia using morphologic analysis of the intraventricular electrogram

Tachycardia detection by implantable antitachycardia devices using rate alone has major limitations. We have examined abnormal ventricular activation in intraventricular electrograms using correlation waveform analysis as a clue to distinguishing ventricular tachycardia from normal sinus rhythm. Thirty episodes of induced, monomorphic ventricular tachycardia were analyzed and compared with sinus rhythm in four groups of patients with (1) normal surface QRS conduction during sinus rhythm without antiarrhythmic drug therapy (5 episodes); (2) intraventricular conduction delay or bundle branch block during sinus rhythm without antiarrhythmic drug therapy (9 episodes); (3) normal surface QRS conduction during sinus rhythm with antiarrhythmic therapy (6 episodes); and (4) intraventricular conduction delay or bundle branch block during sinus rhythm with antiarrhythmic drug therapy (10 episodes). Paired data sets, consisting of lo-second passages of both sinus rhythm and ventricular tachycardia in the same patient, were digitized