IMPLANTATION OF AN AUTOMATIC DEFIBRILLATOR USING A NEW NONTHORACOTOMYAPPROACH

Most current nonthoracotomy systems for defibrillator implantation use monophasic devices. To determine the safety and efficacy of a new non thoracotomy lead configuration when used in conjunction with a device that used biphasic waveforms, 38 consecutive patients were taken to th e operating room for implantation of a Cadence tiered therapy defibril lator system. The lead system consisted of a transvenous coil electrod e positioned at the right atrial-superior vena caval junction, a bipol ar endocardial right ventricular lead and a large patch placed subcuta neously near the cardiac apex. Of the 38 nonthoracotomy defibrillator implantations attempted, 36 (95%) were completed with adequate defibri llation thresholds. The mean defibrillation threshold in these 36 pati ents was less than or equal to 563 +/- 10 V (less than or equal to 20 +/- 1 J). There was no perioperative mortality. Complications included coil lead migration (5), sensing lead migration (1), infection (3), p neumothorax (2), arterial embolism (1), and folding of the subcutaneou s patch with an increase in defibrillation threshold (1). No patient d ied during a median follow-up period of 22 weeks. Fourteen patients (3 9%) had spontaneous sustained ventricular tachyarrhythmias, which were all successfully terminated by the implanted device. Shocks for nonsu stained arrhythmias were aborted in eight patients (22%). Spurious dis charges for sinus tachycardia or atrial fibrillation occurred in six p atients (17%) and were readily diagnosed by examination of the stored electrograms. Thus, implantation of a biphasic tiered therapy defibril lator system using this nonthoracotomy approach is feasible in the maj ority of patients. The major complication associated with this procedu re is lead dislodgment. The clinical course of these patients compares favorably with that of patients who have undergone defibrillator impl antation via an epicardial approach.