Gurunathan S, Hsia P W, Lawton J, Hua D P
Department of Biomedical Engineering, Medical College of Virginia, Richmond, USA.
Biomed Instrum Technol. 1998 Jan-Feb;32(1):48-61.
Random fluctuations of ventricular fibrillation (VF) affect defibrillation; in addition, the heart is more susceptible to defibrillation at a higher absolute VF voltage (AVFV). Shocks delivered at higher AVFV waveforms from a single lead of the electrocardiogram (ECG) are more effective than conventional shocks. The authors investigated a new sensing method using multiple leads for better representation of the depolarization state of the heart. In this non-thoracotomy defibrillation study, a vector waveform derived from three orthogonal surface leads X, Y, and Z was analyzed in real time using two distinct defibrillation lead configurations, P1: RV-coil electrode (-) <--> (SVC-coil electrode + SCP) (+); and P2: RV-coil electrode (+) <--> (SVC-coil electrode + SCP) (-), where (-) represents cathode and (+) anode for the first phase of biphasic shock (RV = right ventricle, SVC = superior vena cava, SCP = subcutaneous patch). A PC-based closed-loop waveform-processing system, the peak-shock method (PSM), was developed to analyze the vector waveforms and trigger a biphasic shock at an AVFV peak. In using this defibrillation technique, an empirical threshold was applied to a weight function consisting of short-term and long-term moving averages of the vector VF waveform. A total of 340 shock trials in nine canine studies resulted in a significantly higher defibrillation success rate for the PSM compared with the conventional random-shock method (RSM), which involved shocking after a fixed VF time (54% for the PSM versus 42% for the RSM, p < 0.03). This further confirms that a susceptible period for defibrillation occurs during VF. The hardware/software design satisfied the requirements for processing the VF vector waveform in real time, and with the help of signal-processing techniques the high VF voltage could be detected at it occurred in real time. In addition, the P2 defibrillation lead configuration was significantly better than the P1 (p < 0.006).
心室颤动（VF）的随机波动会影响除颤效果；此外，在较高的绝对VF电压（AVFV）下，心脏对除颤更敏感。从心电图（ECG）单导联以较高AVFV波形输送的电击比传统电击更有效。作者研究了一种使用多个导联的新传感方法，以便更好地反映心脏的去极化状态。在这项非开胸除颤研究中，使用两种不同的除颤导联配置实时分析从三个正交体表导联X、Y和Z导出的矢量波形，P1：右心室线圈电极（-）<--->（上腔静脉线圈电极+皮下贴片）（+）；P2：右心室线圈电极（+）<--->（上腔静脉线圈电极+皮下贴片）（-），其中（-）代表双相电击第一阶段的阴极，（+）代表阳极（RV = 右心室，SVC = 上腔静脉，SCP = 皮下贴片）。开发了一种基于个人计算机的闭环波形处理系统，即峰值电击法（PSM），以分析矢量波形并在AVFV峰值处触发双相电击。在使用这种除颤技术时，将一个经验阈值应用于由矢量VF波形的短期和长期移动平均值组成的权重函数。在九项犬类研究中的340次电击试验结果显示，与传统随机电击方法（RSM）相比，PSM的除颤成功率显著更高，传统随机电击方法是在固定的VF时间后进行电击（PSM为54%，RSM为42%，p < 0.03）。这进一步证实了在VF期间会出现除颤的易感期。硬件/软件设计满足实时处理VF矢量波形的要求，并且借助信号处理技术可以在VF高电压实时出现时进行检测。此外，P2除颤导联配置明显优于P1（p < 0.006）。
