Schauerte P, Schöndube F A, Grossmann M, Dörge H, Stein F, Dohmen B, Moumen A, Erena K, Messmer B J, Hanrath P, Stellbrink C
Department of Cardiology, University Hospital-RWTH Aachen, Germany.
Circulation. 1998 May 26;97(20):2073-8. doi: 10.1161/01.cir.97.20.2073.
Phase duration of biphasic shocks may be an important determinant of defibrillation success. The purpose of this study was to investigate the effect of changing phase duration of biphasic pulses delivered by 70-microF capacitors on defibrillation energy requirements. This may be clinically relevant for the optimization of implantable cardioverter-defibrillator design and programming.
Defibrillation thresholds (DFTs) were determined for 13 waveforms in 13 pigs by application of a 70-microF capacitance and a transvenous/submuscular lead system. In part I, phase-1 duration varied, preserving a phase-1/phase-2 duration ratio of 60%/40%. The phase-1 durations were 1, 2, 3, 4, 5, and 6 ms. The DFT was lowest (22.9+/-7 J) for phase 1=3 ms compared with phase 1=1 ms (36.4+/-7.5 J), 2 ms (25+/-6.5 J), 4 ms (25+/-7.6 J), 5 ms (30.7+/-7.3 J), or 6 ms (32.9+/-8.1 J) (P<.001). In part II, phase-1 duration was 3 ms but phase-2 duration varied: 0.7, 1.3, 2, 2.7, 3.3, 4, and 6 ms. Significant DFT minima were found at phase 2=2 ms (22.5+/-4.2 J) and phase 2=4 ms (22.5+/-4.2 J) compared with phase 2=0.7 ms (31.7+/-9.3 J), phase 2=3.3 ms (26.7+/-6.1 J), or phase 2=6 ms (28.3+/-6.8 J) (P<.05).
The strength-duration curve of biphasic defibrillation shocks demonstrates a single optimum for phase-1 duration. In contrast, two optima with minimal energy requirements were found for phase-2 duration. Optimization of both phases of low-capacitance biphasic shocks may reduce energy requirements for defibrillation.
双相电击的相位持续时间可能是除颤成功的重要决定因素。本研究的目的是调查改变由70微法电容器提供的双相脉冲的相位持续时间对除颤能量需求的影响。这对于优化植入式心脏复律除颤器的设计和编程可能具有临床相关性。
通过应用70微法电容和经静脉/肌下导联系统，测定了13头猪的13种波形的除颤阈值（DFT）。在第一部分中，第1相持续时间变化，保持第1相/第2相持续时间比为60%/40%。第1相持续时间分别为1、2、3、4、5和6毫秒。与第1相 = 1毫秒（36.4±7.5焦耳）、2毫秒（25±6.5焦耳）、4毫秒（25±7.6焦耳）、5毫秒（30.7±7.3焦耳）或6毫秒（32.9±8.1焦耳）相比，第1相 = 3毫秒时DFT最低（22.9±7焦耳）（P<0.001）。在第二部分中，第1相持续时间为3毫秒，但第2相持续时间变化：0.7、1.3、2、2.7、3.3、4和6毫秒。与第2相 = 0.7毫秒（31.7±9.3焦耳）、第2相 = 3.3毫秒（26.7±6.1焦耳）或第2相 = 6毫秒（28.3±6.8焦耳）相比，在第2相 = 2毫秒（22.5±4.2焦耳）和第2相 = 4毫秒（22.5±4.2焦耳）时发现显著的DFT最小值（P<0.05）。
双相除颤电击的强度 - 时间曲线显示第1相持续时间有一个单一的最佳值。相比之下，第2相持续时间发现有两个能量需求最小的最佳值。优化低电容双相电击的两个相位可能会降低除颤的能量需求。
