We report the first successful totally percutaneous pacing and defibrillation of a single ventricle in a 52-year-old woman who had undergone a classic Fontan operation (atriopulmonary connection) for tricuspid atresia 21 years earlier. Left ventricular pacing and sensing was obtained with a bipolar lead in the lateral cardiac vein, and defibrillation was obtained with a coronary sinus coil lead and an "active can" in the retromammary position to optimize the current vector. This approach has significant potential benefits because it avoids a repeat thoracotomy, with its associated mortality and morbidity.