Unipolar Pectoral Defibrillation Systems

• Published in: Pacing and clinical electrophysiology 1997-02, Vol.20 (2), p.600-606
• Main Authors: REDDY, RAMAKOTA K., BARDY, GUST H.
• Format: Article
• Language: English
• Subjects: defibrillator technology; Defibrillators, Implantable - standards; Defibrillators, Implantable - trends; Equipment Design - instrumentation; Equipment Design - trends; Humans; ICDs; morbidity and mortality; perioperative complications; Treatment Outcome; Ventricular Fibrillation - complications; Ventricular Fibrillation - surgery; Ventricular Fibrillation - therapy
• ISSN: 0147-8389; 1540-8159
• DOI: 10.1111/j.1540-8159.1997.tb06213.x

Over the past 15 years, the implantation of automatic defibrillators has evolved from an obscure, impractical, and often morbid procedure to nearly a routine therapy. Initial large abdominally implanted generators with multiple epicardial leads have given way to much smaller, pectorally implanted systems utilizing only a single lead. These systems are better accepted by physicians and patients and rival recent‐generation pacemakers in their implantation simplicity. Outcomes with single lead defibrillator implantation have been excellent. They are 99% effective at eliminating sudden death in large cohorts of patients, with overall survival of 94.4% at 18 months. Previously significant perioperative complications and mortality associated with epicardial systems have been virtually eliminated. Transvenous single lead systems now provide defibrillation efficacy at a level that makes epicardial leads unnecessary in most patients. Although inappropriate shocks are not a morbid complication, they still occur in approximately 15%–30% of patients. This is an area for improvement in defibrillator therapy, which, though invisible in total mortality statistics, is significant in terms of patient comfort and acceptance. Incremental improvements in pulse generator design and defibrillator lead technology are being made. Perhaps the most interesting new development will be the dual chamber device, incorporating an atrial electrode for sensing, pacing, and perhaps, atrial defibrillation. Such improvements will continue to make device therapy of all arrhythmias more versatile and improve patient comfort both in terms of device size and inappropriate shocks. It is unlikely, however, that further technological advances can further diminish the already small complication rate or improve the already excellent efficacy of current pectoral single lead systems. Defibrillator technology has already reached a maturity where technological improvements are less significant than efforts to better define the patient population who will benefit from the therapy.