We report on a 19-year-old male with a congenital Long-QT syndrome who was admitted to our hospital because of insulation defects of both atrial and ventricular ICD leads resulting in inappropriate delivered shocks and a non-responding pulse generator during telemetrical evaluation. The insulation defects led to multiple arc marks within the ICD pocket and there was a short circuit between denuded leads and the electrically active pulse generator. The high current flow generated sufficient heat to damage several circuits of the generator. A new ICD system was implanted successfully and the postoperative course has been remained uneventful for almost 6 years.