Radiofrequency Catheter Ablation of Upper Septal Idiopathic Left Ventricular Tachycardia Exhibiting Left Bundle Branch Block Morphology

Upper Septal Idiopathic Left Ventricular Tachycardia. Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.