Response to single ventricular extrastimuli during a wide complex tachycardia: What is the mechanism?

A 29-year-old woman with recurrent palpitations was referred for electrophysiological study of wide QRS complex tachycardia. She had no structural heart disease. Baseline ECG showed no ventricular pre-excitation, and baseline HV interval was 40 ms. Dual atrioventricular (AV) nodal physiology was demonstrated. This article is protected by copyright. All rights reserved.