Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology

Upper Septal Idiopathic Left Ventricular Tachycardia. Idiopathic left ventr icular (LV) tachycardia usually exhibits right bundle branch block morpholo gy, There are only a few sporadic cases that exhibit left bundle branch blo ck (LBBB) morphology, We report a patient whose QRS complex during ventricu lar tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (p recordial R wave transition between V-3 and V-4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied t o the LV upper septum, where the earliest endocardial activation was record ed.