(Circulation. 1995;91:445-450.)
© 1995 American Heart Association, Inc.
Articles |
Improved Defibrillation Threshold With a New Epicardial Carbon Electrode Compared With a Standard Epicardial Titanium Patch
Presented in part at the 66th Annual American Heart Association Meeting, November 1993.
From the Departments of Medicine (R.L.C., W.M.S., R.E.I.) and Pathology (D.L.R., R.E.I.), Duke University Medical Center, Durham, NC; the Engineering Research Center for Emerging Cardiovascular Technologies, the Department of Biomedical Engineering of the School of Engineering (W.M.S., R.E.I), Duke University, Durham, NC; and the I. Medical Clinic (E.U.A., E.M., M.P.C), Technische Universität Munich, Germany.
Correspondence to Raymond E. Ideker, MD, PhD, University of Alabama at Birmingham, Volker Hall Room G82A, Box 201, Birmingham, AL 35294.
Background Recent studies show that depending on the type of shock morphology used, 5% to 15% of patients requiring implantable defibrillators cannot be treated with a nonthoracotomy system. In these cases, an epicardial patch–based system becomes necessary. In this study, we investigated a newly developed epicardial carbon electrode as an alternative to a standard epicardial titanium patch.
Methods and Results A tubular epicardial braided carbon
electrode of 7F diameter and 14-cm length applied in a
U-shape to the epicardium was compared with a standard left
ventricular epicardial 15-cm2 titanium mesh patch (CPI
Inc). As cathode, a CPI endocardial lead, a Medtronic lead, or a
carbon-platinum-iridium prototype electrode was used. Ventricular
fibrillation was induced with a 60-Hz generator and allowed to continue
for 10 seconds before a shock was given. Two different biphasic shock
waveforms (3.2/2- and 6/6-millisecond) were delivered by the six
electrode configurations. Eight dogs (weight, 24.5±1.3 kg) underwent
an up-down defibrillation protocol. The order of testing the epicardial
electrodes, the endocardial cathodes, and the waveform was randomized.
With the epicardial carbon electrode, the mean defibrillation threshold
(DFT) energy decreased 39% to 56% and the voltage decreased 24% to
35% compared with the titanium patch: from 8.3±2.5 to 4.9±3.6 J
with
the CPI lead and the 3.2/2-millisecond waveform, from 6.2±2.5 to
2.9±2.1 J with the carbon-platinum-iridium prototype, and from
6.4±3.4 J to 3.5±2.6 J with the Medtronic lead
(P
.05).
The DFT determinations with the 6/6-millisecond biphasic waveform
showed a similar trend with slightly higher values.
Conclusions Compared with a titanium patch, the new braided epicardial electrode significantly decreases the defibrillation energy requirements. This effect can be maximized by using an endocardial carbon-platinum-iridium prototype as cathode and a short duration biphasic waveform.
Key Words: electrodes • defibrillation • epicardial patches
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