Oversensing in a Cardioverter Defibrillator System Caused by Interaction Between Two Endocardial Defibrillation Leads in the Right Ventricle

A 53-year-old male patient underwent implantable cardioverter defibrillator (ICD) implantation with a single lead (Endotak) transvenous system due to recurrent episodes of drug refractory ventricular tachycardia. After pulse generator replacement, inappropriate ICD shocks were observed due to muscle potential sensing. Intraoperatively, the old Endotak lead could not be extracted; therefore, it was transsected and capped. A new lead was inserted and tested without any problems. At the predischarge test, VF was induced and was followed by ICD shocks during sinus rhythm. In another surgical procedure, the old Endotak lead was explanted using a special instrument. The present report demonstrates that two endocardial Endotak leads should be avoided, because the leads may disturb each other and be followed by inappropriate ICD discharges.