Ventricular tachycardia with narrow QRS duration, a right bundle branch block pattern, and right axis deviation abolished by catheter manipulation.

A 25-year-old women underwent electrophysiologic evaluation for sustained normal QRS complex tachycardia with a pattern of right bundle branch block and right axis deviation. Ventricular tachycardia was diagnosed by demonstrating fusion beats, atrioventricular dissociation, and bundle of His potential activation, which began before the onset of each QRS complex. A single ventricular extrastimulus was capable of easily provoking the tachycardia.

Radiofrequency catheter ablation for ventricular tachycardia with a right bundle branch block pattern and left axis deviation.

Ventricular tachycardia (VT) with right bundle branch block QRS morphology and left axis deviation originating in the inferolateral apical segment of the left ventricle was found in a 24-year-old man without overt structural heart disease. Intracardiac recordings during VT showed atrioventricular dissociation with the earliest activation at an apical inferolateral site in the left ventricle, where Purkinje fiber potentials were recorded fusing in the ventricular electrogram. Ventricular pacing was performed at this site, and yielded a QRS morphology identical to the VT.