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Shortening the Second Phase Duration of Biphasic Shocks: Effects of Class III Antiarrhythmic Drugs on Defibrillation Efficacy in Humans
Author(s) -
MERKELY BÉLA,
LUBIŃSKI ANDRZEJ,
KISS ORSOLYA,
HORKAY FERENC,
LEWICKANOWAK EVA,
KEMPA MACIEJ,
SZABOLCS ZOLTÁN,
NYIKOS GYÖRGY,
ZIMA ENDRE,
ŚWIĄTECKA GRAŻYNA,
GELLÉR LÁSZLÓ
Publication year - 2001
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1046/j.1540-8167.2001.00824.x
Subject(s) - defibrillation threshold , amiodarone , medicine , defibrillation , sotalol , cardiology , ventricular fibrillation , ejection fraction , anesthesia , antiarrhythmic agent , heart failure , atrial fibrillation , heart disease
Optimizing the Second Phase of Biphasic Shocks.Introduction: The specific waveform providing optimal defibrillation threshold (DFT) is unknown. We compared the defibrillation efficacy of biphasic pulses with second phases (P2) of 2 and 5 msec in a randomized prospective clinical study. Methods and Results: Intraoperative DFTs of 62 patients (age 54 ± 13 years; ejection fraction 43% ± 17%; amiodarone 47%, d,l‐sotalol 13%) were determined in random order using a binary search protocol. Anodal shocks of 60% tilt first phases (P1) and P2 of 2 msec/5 msec were delivered from two 100‐μ F capacitors between the right ventricular electrode and the test housing of a Phylax 06/XM device. Mean DFT was significantly lower using the shorter P2 ( 9.5 ± 4.5 J vs 11.3 ± 5.2 J; P < 0.0001 ). According to subgroup analysis, the effect of changing P2 duration was only influenced by antiarrhythmic treatment. DFT decreased markedly using the shorter P2 in patients treated with amiodarone ( 10.7 ± 4.9 J vs 13.4 ± 5.6 J; P < 0.00001 ) or d,l‐sotalol ( 6.1 ± 3.3 J vs 9.1 ± 4.6 J; P < 0.05 ). The difference in patients not treated with Class III drugs was found to be insignificant. Chronic amiodarone treatment increased DFT only when the longer P2 was used. Conclusion: Biphasic shocks with shorter P2 should be used in patients undergoing Class III antiarrhythmic treatment.