© 2001 by European Society of Cardiology
ICDS
Clinical evaluation of defibrillation efficacy with a new single-capacitor biphasic waveform in patients undergoing implantation of an implantable cardioverter defibrillator
1Arrhythmia Unit, Cardiovascular Institute, Hospital Clinic, University of Barcelona Spain; 2University Clinic Goettingen, Germany; 3University Clinic Gothenburg, Sweden; 4Guidant Research Brussels, Belgium; 5Guidant Tachyarrhythmia Research St Paul, U.S.A.
Abstract
AIMS: Improvements in the size and shape of implantable cardioverter defibrillators (ICDs) might be obtained by using one capacitor instead of the series connection of two capacitors traditionally used in ICDs. The aim of this study was to determine whether a biphasic waveform delivered from a single 336 µF capacitor had the same defibrillation efficacy as a standard biphasic waveform.
METHODS AND RESULTS: Randomized, paired defibrillation threshold testing was acutely performed in 54 patients undergoing ICD implantation. A standard 140 µF 80% tilt biphasic waveform (two 280 µF capacitors connected in series) was compared with an experimental biphasic waveform delivered from a single 336 µF capacitor at either 60% tilt (33 patients) or 80% tilt (21 patients). All waveforms had a 60/40 phase1/phase2 duration ratio. Compared with the standard waveform, the 60% tilt experimental waveform had a lower delivered energy (6·7±2·8 vs 7·9±3·3 joules,P< 0·02), lower peak voltage (218±43 vs 333±68 V, P< 0·01), and a slightly longer pulse duration (13·4±1·4 vs 10·7±1·1 ms, P< 0·01). Conversely, the 80% tilt experimental waveform had a higher delivered energy (9·1±3·5 vs 6·3±2·4 joules, P< 0·01), a lower peak voltage (234±44 vs 302±51 V,P< 0·01) and a much longer pulse duration (25·7±2·5 vs 11·3±1 ms,P< 0·01).
CONCLUSION: Waveforms delivered from a large capacitance are feasible but require a lower tilt. This technique may allow smaller, thinner ICDs without jeopardizing defibrillation success.
Key Words: Human, defibrillation, pulse-waveform, capacitor, pulse-waveform tilt
Correspondence and/or reprint requests: Dr Josep Brugada, Director of the Arrhythmia Unit, Cardiovascular Institute, Hospital Clinic, c/ Villarroel 170, 08036 Barcelona, Spain. E-mail: jepbrugada{at}grn.es
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