Development of the implantable transvenous cardioverter

The development of the transvenous cardioverter, from the initial animal studies, to the clinical studies using temporary leads, to the initial permanent implants is described. Shocks less than or equal to 2.0 joules synchronized to the QRS complex and delivered through a specially designed catheter electrode placed in the apex of the right ventricle successfully terminate most episodes of ventricular tachycardia in patients. The implanted unit which also serves as a demand ventricular pacemaker, can be used to perform programmed electrophysiologic studies. Future devices must be capable of defibrillation and more accurate arrhythmia detection.