Medical University of South Carolina, Charleston, South Carolina 29425-5920, USA.
J Cardiovasc Electrophysiol. 2013 Mar;24(3):323-7. doi: 10.1111/jce.12041. Epub 2012 Dec 4.
All modern defibrillation systems use biphasic shock waveforms. Typically a fixed tilt waveform is used for implantable defibrillators (ICDs), but a tuned waveform with duration based on shock impedance may be superior based on theoretical calculations.
The objective of this study was to compare defibrillation efficacy of fixed tilt and tuned waveforms.
PROMISE was designed as a prospective, within-patient, randomized study of defibrillation thresholds (DFTs) comparing a tuned (assuming a 3.5 milliseconds membrane time constant) versus a 50/50% tilt waveform. All patients had a left pectoral implant (active can) and testing was performed with a single coil shocking configuration ("SVC coil OFF"). DFTs were measured in random order with a binary search method in 52 patients, using the high-voltage lead impedance to select the pulse widths for both waveforms.
At the DFT, the tuned waveform had similar delivered energy (10.5 ± 6.3 vs 9.5 ± 5.5 J, P = 0.47), stored energy (13.6 ± 7.9 vs 11.3 ± 6.3 J, P = 0.06), peak current (7.5 ± 3.0 vs 6.8 ± 2.2 A, P = 0.09), and delivered voltage (451.0 ± 134.5 vs 411.5 ± 120.7 V, P = 0.05) compared with the 50/50% tilt waveform.
The DFTs for 3.5-millisecond time constant based tuned and 50/50% tilt waveforms are similar using a single coil, left pectoral active can.
所有现代的除颤系统都使用双相电击波形。通常，植入式除颤器（ICD）使用固定倾斜波形，但根据理论计算，基于阻抗的调谐波形可能更优。
本研究旨在比较固定倾斜和调谐波形的除颤效果。
PROMISE 是一项前瞻性、患者内、随机的除颤阈值（DFT）研究，比较了调谐（假设膜时间常数为 3.5 毫秒）与 50/50%倾斜波形。所有患者均有左侧胸壁植入（有源仓），并使用单个线圈电击配置（“SVC 线圈关闭”）进行测试。在 52 名患者中，使用二进制搜索方法以随机顺序测量 DFT，使用高压引线阻抗为两种波形选择脉冲宽度。
在 DFT 时，调谐波形的传递能量（10.5 ± 6.3 与 9.5 ± 5.5 J，P = 0.47）、存储能量（13.6 ± 7.9 与 11.3 ± 6.3 J，P = 0.06）、峰值电流（7.5 ± 3.0 与 6.8 ± 2.2 A，P = 0.09）和传递电压（451.0 ± 134.5 与 411.5 ± 120.7 V，P = 0.05）与 50/50%倾斜波形相似。
使用单个线圈、左侧胸壁有源仓，3.5 毫秒时间常数的调谐和 50/50%倾斜波形的 DFT 相似。
