XXXX compared with monophasic damped sine wave shocks for direct ventricular defibrillation during open heart surgery.

@entity1 @entity1457 @entity764 @entity2224 @entity955 @entity67
BACKGROUND: Biphasic waveform shocks are more effective than monophasic shocks for @entity67 , @entity955 , and defibrillation with implantable defibrillators but have not been studied for open @entity764 . This prospective, blinded, randomized clinical study compares biphasic and monophasic shock effectiveness and establishes intraoperative energy dose-response curves. METHODS: @entity1 undergoing cardiothoracic surgery with bypass cardioplegia were randomly assigned to the monophasic or biphasic shock group. @entity2224 occurring after aortic clamp removal was treated with escalating energies of 2, 5, 7, 10, and 20 J until defibrillation occurred. If @entity2224 persisted, a 20-J crossover shock of the other waveform was used. RESULTS: Cumulative defibrillation success at 5 J, the primary end point of the study, was higher in the biphasic group than in the monophasic group (25 of 50 vs. 9 of 41 defibrillated; P = 0.011). In addition, the biphasic group required lower threshold energy (6.8 vs. 11.0 J; P = 0.003), less cumulative energy (12.6 vs. 23.4 J; P = 0.002), and fewer shocks (2.5 vs. 3.5; P = 0.002). Crossover-shock effectiveness did not differ between groups. Dose-response curves show biphasic shocks to have higher cumulative success rates at all energies tested. CONCLUSIONS: @entity1457 are substantially more effective than monophasic shocks for direct defibrillation. The dose-response curve guides selection of first-shock energy for traditional step-up protocols. Starting at 5 J optimizes for lowest threshold and cumulative energy, whereas 10 or 20 J optimizes for more rapid defibrillation and fewer shocks.
