Alois A. Langer

Termination of malignant ventricular arrhythmias with an implanted automatic defibrillator in human beings.

THE development of a clinically applicable, automatic, implantable defibrillator has been described previously.1 This electronic device is designed to monitor cardiac electrical activity, to recogn...

The Automatic Implantable Defibrillator.: New Modality for Treatment of Life-Threatening Ventricular Arrhythmias

New Modality for treatment of life‐threatening ventricular arrhythmias. The automatic implantable defibrillator continuously monitors cardiac rhythm, identifies ventricuiar fibrillation and then delivers corrective defibrillatory discharges when indicated: it weighs 250 grams and has a volume of 145 cc. When a suitable arrhythmia is detected, a 25 Joule pulse is delivered through a superior vena cava catheter electrode and another electrode placed over the cardiac apex. As oj March 1981, sixteen survivors of multiple cardiac arrests refractory io antiarrhythmic therapy had undergone implantation of the automatic defibrillator. There was no operative mortality and the morbidity was minimal. Electrophysiologic studies were performed before and after surgery to confirm failure of drug therapy and to ensure the devices ability to terminate malignant arrhythmias. Eight spontaneous and fourteen of the seventeen induced malignant arrhythmias were properly recognized and corrected by the device. The discharges were well tolerated by awake patients. A number of problems including recycling delays and spurious discharges have been identified and corrected. There were three late deaths with pulmonary edema noted in two patients, and asystole in one. The autopsies revealed no myocardial damage attributable to the automatic defibrillator. Although the ultimate role of this approach to prevention of sudden arrhythmic death has yet to be determined, the results obtained to date are encouraging and indicate that a useful modality for treating malignant ventricular arrhythmias has been added to our armamentarium. (PACE, Vol. 5, May‐June, 1982)

Automatic Implanted Defibrillator — Initial Clinical Experience

The automatic implantable defibrillator is an electronic device designed to continuously monitor cardiac rhythm, identify ventricular fibrillation and deliver corrective defibrillatory discharges, when indicated. Physically similar to early pacemakers, it weights 250 grams and has a volume of 145 cc (Figure 1). All materials in contact with body tissue are biocompatible. The defibrillating electrodes are made from titanium and silicone rubber. One electrode, designed for placement in the superior vena cava near the right atrial junction, is located on the distal end of an intravascular catheter. The second electrode, in the form of a flexible rectangular patch, is placed extrapericardially over the apex of the heart. The outside surface of the apical electrode is insulated to achieve optimal current distribution. The device is powered by lithium batteries having a projected monitoring life of approximately 3 years or a discharge capability of approximately 100 shocks. The sensing system detects ventricular fibrillation by monitoring a sampled probability density function of ventricular electrical activity.