Matula M H, Brooks M J, Pan Q, Pless B D, Province R A, Echt D S
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tannessee 37232-6300, USA.
Pacing Clin Electrophysiol. 1997 Sep;20(9 Pt 1):2154-62. doi: 10.1111/j.1540-8159.1997.tb04231.x.
Waveform parameters may affect the efficacy of ventricular defibrillation. Certain biphasic pulse waveforms are more effective for ventricular defibrillation than monophasic waveforms, but the optimal biphasic waveform parameters have not been identified. The purpose of this study was to investigate the effects of total pulse duration and the duration of the second (negative) phase on voltage and energy defibrillation requirements using biphasic waveforms. Defibrillation efficacy was evaluated in an isolated rabbit heart model using the Langendorff technique. The biphasic waveform was a truncated exponential with the initial voltage of the second phase equal to 50% of the final voltage of the first phase. An up/down protocol was used to determine the 50% probability-of-success levels (E50) for delivered energy and initial voltage. First, using pulse waveforms with equal positive and negative phase durations, test waveforms with total durations of 4 ms (2 ms positive + 2 ms negative), 6 ms (3 + 3 ms), and 16 ms (8 + 8 ms) were compared to the control waveform of 8 ms (4 + 4 ms) in 30 experiments. Defibrillation voltage requirements with 4 ms (174 +/- 56 V) were higher (P = 0.001) compared to 8 ms (127 +/- 49 V). Defibrillation voltage requirements for the 6-ms and 16-ms waveforms were similar to the 8-ms control waveform. Delivered energies tended to be higher with the 4-ms waveform. A second series of 40 experiments were performed to compare monophasic (4 + 0 ms) and three asymmetric biphasic waveforms (4 + 2 ms, 4 + 8 ms, and 4 + 16 ms) to the symmetric control waveform (4 + 4 ms). The monophasic (2.15 +/- 1.21 J) and the 4 + 16 ms waveform (1.86 +/- 1.09 J) required higher energies (P < or = 0.05) than the control waveform (1.24 +/- 0.41 J and 0.87 +/- 0.7 J, respectively). The monophasic waveform also resulted in greater voltage requirements (223 +/- 64 V) compared to the control waveform (160 +/- 26 V) (P = 0.02). Energy and voltage requirements were similar for the 4 + 2 ms and 4 + 8 ms waveforms compared to the control. Defibrillation requirements with biphasic waveforms were affected by total and second phase duration. For waveforms with equal phase durations, total durations between 6-16 ms resulted in the lowest values for defibrillation. For waveforms with variable second (negative) phase durations, durations ranging from 50%-200% of the first phase did not affect defibrillation efficacy.
波形参数可能会影响心室除颤的疗效。某些双相脉冲波形在心室除颤方面比单相波形更有效，但尚未确定最佳的双相波形参数。本研究的目的是使用双相波形研究总脉冲持续时间和第二（负）相持续时间对电压和能量除颤要求的影响。使用Langendorff技术在离体兔心模型中评估除颤效果。双相波形为截断指数波形，第二相的初始电压等于第一相最终电压的50%。采用上下法确定传递能量和初始电压的50%成功概率水平（E50）。首先，在30次实验中，使用正相和负相持续时间相等的脉冲波形，将总持续时间为4 ms（2 ms正 + 2 ms负）、6 ms（3 + 3 ms）和16 ms（8 + 8 ms）的测试波形与8 ms（4 + 4 ms）的对照波形进行比较。与8 ms（127 +/- 49 V）相比，4 ms（174 +/- 56 V）的除颤电压要求更高（P = 0.001）。6 ms和16 ms波形的除颤电压要求与8 ms对照波形相似。4 ms波形的传递能量往往更高。进行了第二系列的40次实验，以比较单相（4 + 0 ms）和三种不对称双相波形（4 + 2 ms、4 + 8 ms和4 + 16 ms）与对称对照波形（4 + 4 ms）。单相波形（2.15 +/- 1.21 J）和4 + 16 ms波形（1.86 +/- 1.09 J）所需能量（P≤0.05）高于对照波形（分别为1.24 +/- 0.41 J和0.87 +/- 0.7 J）。与对照波形（160 +/- 26 V）相比，单相波形的电压要求也更高（223 +/- 64 V）（P = 0.02）。与对照相比，4 + 2 ms和4 + 8 ms波形的能量和电压要求相似。双相波形的除颤要求受总持续时间和第二相持续时间的影响。对于相持续时间相等的波形，6 - 16 ms之间的总持续时间导致除颤值最低。对于第二（负）相持续时间可变的波形，第一相的50% - 200%范围内的持续时间不影响除颤效果。
