Wessale J L, Bourland J D, Tacker W A, Geddes L A
J Electrocardiol. 1980 Oct;13(4):359-65. doi: 10.1016/s0022-0736(80)80088-4.
The choice of defibrillating waveform is critical in determining the size, battery life, and effectiveness of an automatic implantable defibrillator (AID). The trapezoidal (truncated exponential) waveform is well suited for the AID and its use can be optimized by the selection of appropriate values of pulse duration and tilt. The purpose of this study was to determine the dependence of the threshold peak current (the minimum peak current necessary to defibrillate the ventricles) on pulse duration and tilt for a bipolar catheter electrode configuration. Successive fibrillation-defibrillation trials were performed in 30 dogs anesthetized with sodium pentobarbital (30 mg/kg). The defibrillating pulse was applied via a bipolar-electrode catheter positioned such that the electrodes were located in the right ventricle at the apex and in the superior vena cava. The threshold peak current was determined in each dog for trapezoidal waveforms with 80%, 65%, 50%, and less than 5% tilt and with pulse durations of 2, 5, 10, 15, and 20 milliseconds. From a total of 600 threshold peak-current values, a strength-duration curve was derived for each value of tilt. The threshold peak current dose (peak current divided by body weight) increased with increasing tilt and decreasing duration. The threshold average current dose (average current over the duration of the defibrillating pulse divided by body weight) was IAV = 0.26 + 0.47/d, where d is the pulse duration in milliseconds and IAV is the average current in amperes per kilogram. If catheter apparent impedance is known, the minimum capacitance and output voltage necessary for defibrillation can be inferred from the strength-duration curves. From these data one can quantitatively assess the effect of trapezoidal waveform shape on the design criteria for the AID.
除颤波形的选择对于确定自动植入式除颤器（AID）的尺寸、电池寿命和有效性至关重要。梯形（截断指数）波形非常适合AID，通过选择合适的脉冲持续时间和倾斜度值可以优化其使用。本研究的目的是确定双极导管电极配置下阈值峰值电流（使心室除颤所需的最小峰值电流）对脉冲持续时间和倾斜度的依赖性。对30只用戊巴比妥钠（30mg/kg）麻醉的犬进行了连续的颤动-除颤试验。通过双极电极导管施加除颤脉冲，电极位于右心室心尖和上腔静脉。对每只犬测定了倾斜度为80%、65%、50%和小于5%且脉冲持续时间为2、5、10、15和20毫秒的梯形波形的阈值峰值电流。从总共600个阈值峰值电流值中，为每个倾斜度值得出了强度-持续时间曲线。阈值峰值电流剂量（峰值电流除以体重）随倾斜度增加和持续时间减少而增加。阈值平均电流剂量（除颤脉冲持续时间内的平均电流除以体重）为IAV = 0.26 + 0.47/d，其中d为脉冲持续时间（毫秒），IAV为每千克安培的平均电流。如果已知导管表观阻抗，则可以从强度-持续时间曲线推断出除颤所需的最小电容和输出电压。根据这些数据，可以定量评估梯形波形形状对AID设计标准的影响。
