Doshi Shephal K, Pittaro Michael D, Reeves Russell, Boyce Ker, Payne John P, Kroll Mark W, Graumann Robert J, Oza Ashish L, Val-Mejias Jesus E
Saint John's Health Center, Santa Monica, California, USA.
Pacing Clin Electrophysiol. 2012 Oct;35(10):1253-61. doi: 10.1111/j.1540-8159.2012.03500.x. Epub 2012 Aug 20.
The efficacy of tuned defibrillation waveforms versus the nominal fixed-tilt waveform has been previously studied. However, the optimal membrane time constant for tuning was not known. The POWER (Pulsewidth Optimized Waveform Evaluation tRial) trial was designed to determine the optimal membrane time constant for programming "tuned" biphasic waveforms.
This acute, multicenter study included 121 implantable cardioverter-defibrillator/cardiac resynchronization therapy defibrillator patients who were randomized at implant to any two of the three membrane time constant waveforms (2.5, 3.5, and 4.5 ms). Fixed pulse widths were programmed using the measured high voltage shock impedance. The defibrillation threshold (DFT) estimates were obtained using a hybrid protocol starting with an upper limit of vulnerability estimate followed by a step-up/step-down ventricular fibrillation induction process.
DFT voltage was significantly lower using 3.5- and 4.5-ms waveforms as compared to the 2.5-ms waveform (P = 0.004 and 0.035, respectively). DFT voltage with both 3.5- and 4.5-ms waveforms was ≤ that obtained with the 2.5-ms waveform in 78.5% of the cases. The mean difference in DFT voltage using the 3.5-ms waveform and the 4.5-ms waveform was not significant (P = 0.4). However, the 3.5-ms waveform gave a lower DFT than the 4.5-ms waveform in 19 patients although the reverse was true in only nine (P = 0.02 not significant for multiple comparisons).
The use of a 3.5- or 4.5-ms time constant-based waveforms had lower DFTs when compared to the 2.5-ms waveform. This study suggests that the first defibrillation attempt at implantation should be with 3.5- or 4.5-ms time constant-based waveforms. The 3.5-ms-based waveform trended toward the best choice.
之前已经研究了调谐除颤波形与标称固定倾斜波形的疗效。然而，调谐的最佳膜时间常数尚不清楚。POWER（脉宽优化波形评估试验）旨在确定编程“调谐”双相波形的最佳膜时间常数。
这项急性多中心研究纳入了121例植入式心脏复律除颤器/心脏再同步治疗除颤器患者，这些患者在植入时被随机分配至三种膜时间常数波形（2.5、3.5和4.5毫秒）中的任意两种。使用测量的高压电击阻抗来编程固定脉宽。除颤阈值（DFT）估计值通过混合方案获得，该方案首先是易损性估计上限，然后是逐步递增/递减的室颤诱发过程。
与2.5毫秒波形相比，使用3.5毫秒和4.5毫秒波形时DFT电压显著更低（分别为P = 0.004和0.035）。在78.5%的病例中，3.5毫秒和4.5毫秒波形的DFT电压均≤2.5毫秒波形所获得的DFT电压。使用3.5毫秒波形和4.5毫秒波形时DFT电压的平均差异不显著（P = 0.4）。然而，在19例患者中，3.5毫秒波形的DFT低于4.5毫秒波形，而只有9例患者情况相反（P = 0.02，多重比较无显著性）。
与2.5毫秒波形相比，使用基于3.5或4.5毫秒时间常数的波形时DFT更低。这项研究表明，植入时首次除颤尝试应采用基于3.5或4.5毫秒时间常数的波形。基于3.5毫秒的波形趋向于最佳选择。
