Ventricular Fibrillation Triggered during Radiofrequency Energy Delivery for Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia

Verapamil-sensitive idiopathic left ventricular tachycardia (VT) can be suppressed by radiofrequency ablation (RF) on the Purkinje network. RF delivered on the Purkinje fibers triggers premature ventricular contractions or repetitive ventricular response and disappear after cessation of RF. We present a case with idiopathic left VT who represented ventricular fibrillation (VF) during RF on the Purkinje network. Case: A 15-year-old male admitted our hospital because of recurrent sustained VT with QRS morphology of right bundle branch block and left axis deviation. Intravenous verapamil terminated VT. However, electrophysiologic study could not induce VT even if isoproterenol infusion. We delivered RF energy at the distal left posterior fascicular region where Purkinje potentials were recorded during sinus rhythm with pace-mapping QRS morphology mimicking VT-QRS. Shortly after RF delivery, polymorphic VT induced and degenerated into VF. RF deliveries around the VF site induced similar responses. Then, we created RF lesions on the Purkinje fibers more proximal to the VF-induced sites. No VT was documented 3 years after ablation. Conclusion: Purkinje network appears to have potential role for VF induction. RF ablations at the proximal site of the critical Purkinje network can prevent VT/VF occurrence in such case.