Radiofrequency catheter ablation of ventricular tachycardia originating in the left posterior and left anterior fascicles in a patient with prior myocardial infarction.

A 61-year-old man with prior anteroseptal myocardial infarction (ejection fraction: 40%) presented with recurrent episodes of palpitations. Twelve-lead ECG during palpitations showed an incessant ventricular tachycardia (VT1) with right bundle branch block (RBBB) morphology and inferior axis. Electrophysiologic study revealed that the clinical VT originated from the anterolateral left ventricle. A Purkinje potential preceded onset of the QRS complex by 34 ms. Radiofrequency ablation guided by the Purkinje potential terminated the VT1. Another ventricular tachycardia (VT2) showing RBBB morphology with superior axis and originating from the posteroseptal left ventricle, was induced by programmed ventricular stimulation. A Purkinje potential preceded onset of the local ventricular potential by 120-130 ms in this VT. Radiofrequency ablation guided by the Purkinje potential terminated the VT2.