THE LEFT SUBCLAVIAN VEIN AS AN ALTERNATIVE SITE FOR IMPLANTATION OF THE 2ND DEFIBRILLATION LEAD

The optimal placement for the second defibrillation lead in a two-lead system has never been addressed. We retrospectively reviewed the data of 33 patients with an average age of 59.2 years (range 41-78 years), predominantly male (n = 29), who underwent implantation of a cardiove rter defibrillator (ICD) for treatment of ventricular tachycardia (n = 19) or ventricular fibrillation (n = 14). In all patients an attempt was made to implant and endovenous ICD device (leads only, no subcutan eous patch). In group I (n = 18) the defibrillation anode, a separate unipolar lead, was placed in the common position, the superior vena ca va. In group II (n = 15) the lead was placed in the left subclavian ve in. At least two consecutive shocks reverting ventricular fibrillation at energies less than or equal to 24J were required for implantation of the ICD device. All shocks were monophasic. The success rate of end ovenous defibrillation was significantly higher in group II than in gr oup I (67% vs 28%, P < 0.05). Thus, it could be demonstrated that the position of the defibrillation anode can influence the defibrillation efficacy in transvenous ICD systems. Prospective randomized trials are needed to investigate the optimal position for the second defibrillat ion electrode, which may gain increasing importance as soon as dual ch amber ICDs become available.