Surface 12-lead ECG in bundle branch reentrant ventricular tachycardia

Left panel: 12 lead ECG during sinus rhythm; there is a left bundle branch block-type intraventricular conduction delay.
Right panel: 12 lead ECG during VT; there is a remarkable similarity in QRS morphology during VT and sinus rhythm. The HV interval during sinus rhythm was 65 milliseconds, suggesting underlying His-Purkinje conduction disease.