IRIDIUM-OXIDE-COATED DEFIBRILLATION ELECTRODE - REDUCED SHOCK POLARIZATION AND IMPROVED DEFIBRILLATION EFFICACY

Background Transvenous implantable cardioverter-defibrillator (ICD) le ads are designed to deliver electric shocks to the heart for terminati on of ventricular dysrhythmias. However, the efficiency of different l ead materials has not been well studied. This study compares an ICD le ad coated with iridium oxide (IROX), a material that. reduces shock-in duced polarization, with an otherwise identical, uncoated lead. Method s and Results The defibrillation threshold (DFT) was determined in 13 swine with both IROX-coated and uncoated ICD leads paired with an unco ated ''can'' electrode, The leads were exchanged through a Teflon shea th to reproduce the intracardiac position. The delivered energy DFT of the IROX-coated lead was 15.9 +/- 5.4 J and was significantly lower t han the delivered energy DFT of the uncoated lead (19.1 +/- 5.1 J; P<. 006). The initial lead impedance was equivalent in both leads (IROX, 4 1.7 +/- 5.8 Omega; uncoated, 41.3 +/- 4.7 Omega; P=NS) at DFT. However , the impedance rose by 7.3 +/- 2.0 Omega during the first phase and b y 3.7 +/- 2 Omega during the second phase with the uncoated lead, wher eas the corresponding impedance change was 1.0 +/- 0.3 Omega during ph ase 1 and 1.6 +/- 0.5 Omega during phase 2 (P<.01 each phase) when the IROX-coated lead was used, Conclusions This study shows that an IROX coating of this lead system significantly lowers the DFT energy in the swine model. The blunting of the impedance rise by the IROX coating t hat is seen is consistent with, a reduction in electrode polarization.