PMID: 9436776Jan 22, 1998Paper

The effects of ventricular fibrillation duration and a preceding unsuccessful shock on the probability of defibrillation success using biphasic waveforms in pigs

Journal of Cardiovascular Electrophysiology
S WindeckerR E Ideker

Abstract

While the defibrillation threshold has been reported to increase with ventricular fibrillation (VF) duration for monophasic waveforms, the effect of VF duration for biphasic waveforms is unknown. The ED 50 requirements (the 50% probability of defibrillation success) for an endocardial lead system, which included a subcutaneous array, were determined by logistic regression using a recursive up-down algorithm for a biphasic waveform (6/6 msec). The study was performed in two parts, each with eight pigs. In part 1, ED 50 was compared for shocks delivered after 10 seconds of VF and for shocks delivered after 20 seconds of VF following a failed first shock at 10 seconds. Energy at ED 50 decreased from 6.5 +/- 0.9 J for shocks delivered after 10 seconds of VF to 4.9 +/- 0.8 J (P < 0.01) for shocks delivered after 20 seconds. To determine if improved second shock efficacy was a result of preconditioning by the failed first shock or a function of VF duration, part 2 of the study compared defibrillation efficacy between shocks delivered after 10 seconds of VF with shocks delivered after 20 seconds of VF with and without a failed first shock at 10 seconds. Mean energy at ED 50 decreased from 10.1 +/- 2.4 J for shocks delivered after 10 s...Continue Reading

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Citations

Feb 6, 1999·Journal of the American College of Cardiology·S WindeckerA E Epstein
Jan 21, 2000·Pacing and Clinical Electrophysiology : PACE·P R RobertsJ M Morgan
Dec 10, 1999·Pacing and Clinical Electrophysiology : PACE·Y YamanouchiP J Tchou
Jun 8, 2002·Physiological Measurement·James EasonRobert A Malkin

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