Pleomorphic ventricular tachycardia originating from Purkinje fiber network of left anterior fascicle.

A 55-year-old woman with recurrent syncope and palpitation experienced polymorphic ventricular tachycardia (VT) and more than 3 monomorphic VTs with a right bundle branch block configuration as inferior, middle, and superior axis. During the pleomorphic VT, the diastolic potential (dp) was recorded at the anterolateral left ventricle. Changes in the QRS morphology were associated with the time between dp and onset of QRS complex (dp-V interval), and prolongation of dp-V interval terminated the VT. In addition, the delayed potentials were seen during sinus rhythm around this area. Delivery of radiofrequency current targeting the delayed potentials abolished all the VTs. Different exits from relatively large area of slow conduction in the left anterior fascicle might have produced the pleomorphic VTs.