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(Circulation. 1997;96:3732-3736.)
© 1997 American Heart Association, Inc.

Articles

Iridium Oxide–Coated Defibrillation Electrode

Reduced Shock Polarization and Improved Defibrillation Efficacy

Mark J. Niebauer, MD, PhD; Bruce Wilkoff, MD; Yoshio Yamanouchi, MD; Todor Mazgalev, PhD; Kent Mowrey, MS; ; Patrick Tchou, MD

From the Section of Electrophysiology and Pacing, Department of Cardiology, The Cleveland Clinic Foundation, Cleveland, Ohio.

Correspondence to Mark J. Niebauer, MD, PhD, Desk F-15, Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195. E-mail niebaum{at}cesmtp.ccf.org

Background Transvenous implantable cardioverter-defibrillator (ICD) leads are designed to deliver electric shocks to the heart for termination of ventricular dysrhythmias. However, the efficiency of different lead materials has not been well studied. This study compares an ICD lead coated with iridium oxide (IROX), a material that reduces shock-induced polarization, with an otherwise identical, uncoated lead.

Methods and Results The defibrillation threshold (DFT) was determined in 13 swine with both IROX-coated and uncoated ICD leads paired with an uncoated "can" electrode. The leads were exchanged through a Teflon sheath to reproduce the intracardiac position. The delivered energy DFT of the IROX-coated lead was 15.9±5.4 J and was significantly lower than 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, 41.7±5.8 ; uncoated, 41.3±4.7 ; P=NS) at DFT. However, the impedance rose by 7.3±2.0 during the first phase and by 3.7±2 during the second phase with the uncoated lead, whereas the corresponding impedance change was 1.0±0.3 during phase 1 and 1.6±0.5 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 that is seen is consistent with a reduction in electrode polarization.

Key Words: defibrillation • electrical stimulation • arrhythmia • fibrillation • ventricles

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