The automatic implantable defibrillator was developed in the USA by Mirowski. This device automatically detects ventricular fibrillation or ventricular tachycardia and delivers a low energy (30 J) shock directly to the myocardium via patch electrodes on the epicardial surface or through a combination of a pericardial patch and an endocardial wire. These devices are being implanted in large numbers in the USA and represent a major contribution to the management and refractory ventricular arrhythmias. Unfortunately their high cost has limited their use in this country despite impressive clinical results.