Strickberger S A, Hummel J D, Horwood L E, Jentzer J, Daoud E, Niebauer M, Bakr O, Man K C, Williamson B D, Kou W
Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022.
J Am Coll Cardiol. 1994 Oct;24(4):1069-72. doi: 10.1016/0735-1097(94)90871-0.
The purpose of this study was to determine whether the polarity of a monophasic shock used with a transvenous lead system affects the defibrillation threshold.
The ability to implant an automatic defibrillator depends on achieving an adequate defibrillation threshold.
A transvenous defibrillation lead with distal and proximal shocking electrodes was used in this study. In 29 consecutive patients, the defibrillation threshold, using a stepdown protocol was determined twice in random order: 1) with the distal coil as the anode, and 2) with the polarity reversed. Only the 20 patients in whom an adequate defibrillation threshold could be obtained with the transvenous lead alone were included in this study. These patients were 61 +/- 14 years old (mean +/- SD) and had a mean ejection fraction of 28 +/- 12%.
The mean defibrillation threshold was 11.5 +/- 5.0 J with the distal coil as the anode versus 16.9 +/- 7.7 J with the distal coil as the cathode (p = 0.04). The defibrillation threshold was lower by a mean of 9 +/- 7 J with the former configuration in 14 patients and was lower by a mean of 7 +/- 6 J with the latter configuration in 3 patients; in 3 patients it was the same with both configurations. Use of a subcutaneous patch was avoided in five patients by utilizing the distal electrode as the anode.
Defibrillation thresholds with monophasic shocks are approximately 30% lower with the distal electrode as the anode. The use of anodal shocks may obviate the need for a subcutaneous patch and allow more frequent implantation of a transvenous lead system.
本研究旨在确定经静脉导联系统使用的单相电击的极性是否会影响除颤阈值。
植入自动除颤器的能力取决于达到足够的除颤阈值。
本研究使用了带有远端和近端电击电极的经静脉除颤导联。在29例连续患者中，采用逐步降低方案随机测定两次除颤阈值：1）以远端线圈为阳极，2）极性反转。本研究仅纳入了20例仅通过经静脉导联就能获得足够除颤阈值的患者。这些患者年龄为61±14岁（平均±标准差），平均射血分数为28±12%。
以远端线圈为阳极时，平均除颤阈值为11.5±5.0 J，而以远端线圈为阴极时为16.9±7.7 J（p = 0.04）。在14例患者中，前一种配置的除颤阈值平均降低9±7 J，在3例患者中，后一种配置的除颤阈值平均降低7±6 J；在3例患者中，两种配置的除颤阈值相同。通过将远端电极用作阳极，5例患者避免了使用皮下贴片。
以远端电极作为阳极时，单相电击的除颤阈值约低30%。使用阳极电击可能无需皮下贴片，并允许更频繁地植入经静脉导联系统。
