The automatic implantable cardioverter/defibrillator

Abstract

The automatic implantable defibrillator (AID) was developed in the 1970s, and the first clinical model was tested in humans in 1980. The automatic implantable cardioverter/defibrillator (AICD), a second-generation device, is capable of both cardioversion and defibrillation. Clinical studies have demonstrated the AICD to be efficacious in terminating episodes of spontaneous as well as laboratory-induced ventricular tachycardia or fibrillation. Preliminary evidence suggests that the device reduces the sudden-death rate in patients at high risk for recurrent cardiac arrest attributable to malignant ventricular tachyarrhythmias. There are still a number of problems related to the device, including those of limited battery life, unpleasant discharges, inability to determine the exact cause of the discharge, inappropriate sensing of supraventricular tachyarrhythmia, especially with the rate-only units, a relatively short sense time (time from onset of the arrhythmia to initiation of the charging process) leading to spurious discharges in response to nonsustained ventricular tachyarrhythmias, potential pacemaker interaction, lack of programmability after implantation, and the requirement for major surgery. The device is being further refined and developed, and may well prove to be a cost-effective way of managing patients with refractory ventricular tachyarrhythmias.