Winkle R A, Mead R H, Ruder M A, Smith N A, Buch W S, Gaudiani V A
Cardiovascular Section, Sequoia Hospital, Redwood City, California.
Circulation. 1990 May;81(5):1477-81. doi: 10.1161/01.cir.81.5.1477.
The currently available automatic implantable cardioverter-defibrillator has proven highly successful for termination of ventricular tachycardia and fibrillation. Newer devices, however, permit lower energy shocks to be delivered initially and longer episodes of arrhythmia to occur before shocks are delivered. These changes may result in longer durations of arrhythmia before successful termination. Little is known about the effects of the duration of ventricular fibrillation on the efficacy of defibrillating shocks. In this study, we examined the efficacy of defibrillating shocks in 22 patients undergoing automatic implantable cardioverter-defibrillator implantation or generator change. Defibrillating shocks ranging from 300 to 600 V (5.9-24.2 J) were delivered in matched pairs after 5 and 15 seconds of ventricular fibrillation. For the 300-V shocks (5.9 J), defibrillation was accomplished in 82% of patients when the shocks were given after 5 seconds of ventricular fibrillation and in only 45% of patients when the shocks were delivered after 15 seconds (p less than 0.01). At higher energies, there was no difference in the efficacy of defibrillation shocks delivered after 5 compared with 15 seconds of ventricular fibrillation. The postshock aortic, systolic, and diastolic blood pressures were significantly lower when the shocks were given after 15 seconds of ventricular fibrillation than after only 5 seconds. We conclude that the duration of ventricular fibrillation affects defibrillation efficacy especially at energies that are relatively low compared with maximal device outputs and that longer episodes of ventricular fibrillation cause more postshock hemodynamic depression. These observations have implications for defibrillation threshold testing at the time of device implantation and for the design and programming of future automatic implantable antitachycardia devices.
目前可用的自动植入式心脏复律除颤器已被证明在终止室性心动过速和颤动方面非常成功。然而，更新的设备允许最初施加较低能量的电击，并在电击之前允许更长时间的心律失常发作。这些变化可能导致在成功终止之前心律失常持续时间更长。关于室颤持续时间对除颤电击效果的影响知之甚少。在本研究中，我们检查了22例接受自动植入式心脏复律除颤器植入或发生器更换的患者的除颤电击效果。在室颤5秒和15秒后以配对方式施加300至600V（5.9 - 24.2J）的除颤电击。对于300V电击（5.9J），在室颤5秒后给予电击时，82%的患者实现了除颤，而在室颤15秒后给予电击时，只有45%的患者实现了除颤（p小于0.01）。在更高能量下，室颤5秒后与15秒后施加的除颤电击效果没有差异。当在室颤15秒后给予电击时，电击后的主动脉收缩压和舒张压显著低于仅在5秒后给予电击时。我们得出结论，室颤持续时间影响除颤效果，特别是在与设备最大输出相比相对较低的能量水平下，并且更长时间的室颤会导致电击后更严重的血流动力学抑制。这些观察结果对设备植入时的除颤阈值测试以及未来自动植入式抗心动过速设备的设计和编程具有重要意义。
