Strickberger S A, Man K C, Daoud E, Neary M P, Horwood L E, Niebauer M, Hummel J D, Morady F
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022, USA.
J Am Coll Cardiol. 1995 Jun;25(7):1605-8. doi: 10.1016/0735-1097(95)00039-7.
The purpose of this study was to determine whether the polarity of the first phase of a biphasic shock affects the defibrillation threshold.
The polarity of a monophasic shock has been shown to affect the defibrillation threshold.
A transvenous defibrillation lead with distal and proximal shocking electrodes was used in this study. In 15 consecutive patients, the defibrillation threshold was determined twice using a step-down protocol, in random order: with the distal coil as the anode for the initial phase (anodal biphasic shock) and with the polarity reversed (cathodal biphasic shock). The power to detect a 5.0-J difference in this study is 0.96. These patients were 61 +/- 11 years old (mean +/- SD), and the mean left ventricular ejection fraction was 0.32 +/- 0.10.
Mean defibrillation threshold using anodal biphasic shocks was 9.9 +/- 4.8 J, compared with 9.5 +/- 4.2 J using cathodal biphasic shocks (p = 0.8). In three patients the defibrillation threshold was lower by a mean of 6.3 +/- 2.9 J with the former configuration; in three patients the defibrillation threshold was lower by a mean of 6.7 +/- 2.5 J with the latter configuration; and in nine patients it was the same. Using the standard cathodal configuration, a defibrillation threshold < or = 10 J was obtained in approximately 70% of patients, and a subcutaneous patch was not required in any patient.
The polarity of the first phase of a biphasic shock used with a single transvenous lead does not affect the defibrillation threshold.
本研究旨在确定双相电击第一阶段的极性是否会影响除颤阈值。
已证实单相电击的极性会影响除颤阈值。
本研究使用了带有远端和近端电击电极的经静脉除颤导线。连续15例患者，采用逐步降低方案，以随机顺序两次测定除颤阈值：初始阶段将远端线圈作为阳极（阳极双相电击），并将极性反转（阴极双相电击）。本研究中检测5.0 J差异的功效为0.96。这些患者年龄为61±11岁（均值±标准差），平均左心室射血分数为0.32±0.10。
阳极双相电击的平均除颤阈值为9.9±4.8 J，而阴极双相电击为9.5±4.2 J（p = 0.8）。在3例患者中，前一种配置下除颤阈值平均低6.3±2.9 J；在3例患者中，后一种配置下除颤阈值平均低6.7±2.5 J；在9例患者中两者相同。使用标准阴极配置时，约70%的患者除颤阈值≤10 J，且所有患者均无需皮下贴片。
使用单根经静脉导线时，双相电击第一阶段的极性不影响除颤阈值。
