[Transvenous subcutaneous implantation technique of the cardioverter/defibrillator]

For years the high efficacy of implantable cardioverter-defibrillators (ICD) to prevent sudden cardiac death was impaired by the substantial perioperative mortality of the therapy. With the introduction of transvenous-subcutaneous defibrillation leads, thoracotomy could be abandoned and perioperative mortality was reduced to less than 1%. Despite frequent lead complications as dislocations, conductor fractures and isolation failures, long-term efficacy in termination of ventricular tachyarrhythmias remained approximately 98% and prevention of sudden cardiac death was not impaired. All nonthoracotomy defibrillation lead systems involve an endocardial right ventricular lead usually introduced from the left cephalic vein or directly via the subclavian vein. This lead has a pace/sense tip and at least one defibrillation electrode located in the right ventricle. Additionally, a second transvenous electrode and/or a subcutaneous patch or array electrode or the pulse generator shell has to be used for defibrillation. In combination with the biphasic defibrillation waveform, virtually all patients can be defibrillated using a combination of these electrodes. In most patients defibrillation is possible with transvenous electrodes alone and there is no need for an additional subcutaneous electrode. Smaller pulse generators have already been implanted in a subpectoral position--in many patients allowing a single incision approach as used for pacemaker implantation. Ultimately, with even smaller pulse generators ICDs should be implantable like present pacemakers in local anesthesia. This overview covers the history, models, practical aspects of implantation and testing, efficacy and complications of transvenous/subcutaneous defibrillation leads. Figures show the impact of the surgical approach on the frequency of de novo ICD implantations, X-rays of nearly all current bipolar and tripolar transvenous subcutaneous ICD lead systems, transvenous-epicardial hybrid systems and various complications. Additional figures cover lead complications not visible on X-rays. Defibrillation thresholds are compared for various lead configurations. Sensing amplitudes and pacing thresholds are compared for bipolar and pseudobipolar sense/pace leads as well as for different cardiac diseases. Tables summarize the main characteristics of current transvenous and subcutaneous ICD leads and external devices for intraoperative testing of ICD leads as well as the complications of transvenous/subcutaneous leads in three multicenter studies.