[Cardioverter-defibrillator implantations without thoracotomy: clinical experience with various electrode configurations and defibrillation wave forms of an endocardial/subcutaneous defibrillator system].

Twenty-seven consecutive patients with refractory ventricular arrhythmias were investigated for implantation of an nonthoracotomy cardioverter-defibrillator lead system. Supply with a nonthoracotomy lead system could be achieved in 25 of 27 patients (92.5%), while implantation proved impossible in two patients due to elevated defibrillation thresholds. After implantation of an endocardial defibrillation electrode no differences were found compared to the implantation of an endocardial defibrillation electrode with a subcutaneous chest wall defibrillation patch with regard to the defibrillation thresholds obtained for monophasic defibrillation waveform. Supply with an endocardial defibrillation lead system was successful in 18 of 25 patients (72%). Ten consecutive patients with implantation of an endocardial defibrillation lead system alone were compared for defibrillation efficacy following monophasic and biphasic defibrillation waveforms. Defibrillation with biphasic waveforms led to a decrease in the necessary defibrillation energy from 19 J (4.6 J) to 10 J (4.0 J). There was occurrence of refractory ventricular fibrillation that could not be controlled by endocardial and transthoracic defibrillation in two patients during the intraoperative testing of defibrillation thresholds. In both cases these arrhythmias could be terminated by the described method of endocardial/extrathoracic defibrillation (200 J). Further perioperative complications were not observed. Over a mean follow-up of 6.8 (1-17) months all patients demonstrated regular functioning of the cardioverter-defibrillator. Dislocation of defibrillation electrodes did not occur. Implantation of a cardioverter-defibrillator can be performed without thoracotomy in the majority of cases. The use of defibrillator systems with biphasic waveform widens the scope for implantation of nonthoracotomy defibrillating lead systems.