Differentiation of Ventricular Tachycardia from Junctional Tachycardia with Aberrant Conduction

A case of regular tachycardia with an intraventricular conduction defect and possible retrograde P waves is reported. The condition was interpreted as being either ventricular tachycardia with 1:1 retrograde V-A conduction or an atrioventricular junctional tachycardia with aberrant intraventricular conduction. Atrial pacing resulted in normalization of intraventricular conduction as well as the production of fusion beats and allowed a definitive diagnosis of ventricular tachycardia. The use of atrial pacing as a diagnostic technique has not been previously discussed in the literature.