The material and implantation technique of the implantable defibrillator developed by M. Mirowski and used by the authors in 3 patients are described. Through lateral thoracotomy, 4 electrodes are installed, including one patch on the apex of the heart. In case of sustained ventricular arrhythmia the instrument delivers, after less than 30 seconds, a 25 joules shock increased to 30-35 joules if this fails. The results were very encouraging since conversion of severe ventricular arrhythmia was obtained in all 3 patients after the first shock. There was no false detection or inappropriate start. The limitations and indications of the technique are discussed and compared with other treatments of ventricular arrhythmia.