TRANSVENOUS DEFIBRILLATION LEADS - IS THERE AN IDEAL POSITION OF THE DEFIBRILLATION ANODE

A potential benefit of two-lead transvenous defibrillation systems is the ability to independently position the defibrillation electrodes, c hanging the vector field and possibly decreasing the DFT. Using the ne w two-lead transvenous TVL lead system, we studied whether DFT is infl uenced by SVC lead position and whether there is an optimal position. TVL leads and Cadence pulse generators were implanted in 24 patients. No intraoperative or perioperative complications were observed. In eac h patient, the DFTs were determined for three SVC electrode positions, which were tested in random order: the brachiocephalic vein, the mid- RA, and the RA-SVC junction. The mean DFTs in the three positions were not statistically different, nor was any single lead position consist ently associated with lower DFTs. However, an optimal electrode positi on was identified in 83% of patients, and the DFT from the best lead p osition for each patient was significantly lower than for any one of t he electrode positions (P < 0.01). The mean safety margin for the best SVC lead position was approximately 27 J. These results demonstrate t he advantage of a two-lead system, as well as the importance of testin g multiple SVC lead positions when the patient's condition permits. Bo th of these factors can decrease the DFT and maximize the defibrillati on safety margin. This will become increasingly important as pulse gen erator capacitors become smaller (as part of the effort to decrease ge nerator size) and the energy output of the generators consequently dec reases.