Callihan R L, Idriss S F, Dahl R W, Wolf P D, Smith W M, Ideker R E
Department of Medicine Center, Duke University, Durham, North Carolina, USA.
J Am Coll Cardiol. 1995 May;25(6):1373-9. doi: 10.1016/0735-1097(94)00558-8.
This study sought to assess the effect of passive "bystander" epicardial electrodes on defibrillation efficacy.
We hypothesized that an inactive epicardial patch placed in an area of low potential gradient from an endocardial electrode shock might affect defibrillation efficacy through its effects on the shock field and the underlying potential gradient.
We studied the effects of an inactive 18-cm2 titanium mesh patch placed on the anterolateral left ventricular epicardium on the 50% probability of successful defibrillation. A biphasic shock with both phases 6 ms in duration was delivered between superior vena cava and right ventricular catheter electrodes 10 s after the electrical induction of ventricular fibrillation. Six dogs underwent an up/down defibrillation protocol randomized with or without the patch on the heart.
Mean 50% (+/-) probability point for energy doubled with the conductive patch on the heart, from 8.0 +/- 3.2 to 16.8 +/- 7.0 J (p < 0.01), and leading-edge voltage increased from 334 +/- 64 to 477 +/- 98 V (p < 0.01). Mean 50% probability points for energy and leading-edge voltage were not significantly changed when the procedure was repeated using a nonconductive patch in another six dogs as a control group. In a saline-saturated foam model, measurements from electrodes placed around and under the patch revealed a 72% mean decrease in the potential gradient in the foam under the conductive patch.
A passive defibrillator patch can markedly increase the energy requirements for defibrillation, probably by decreasing the potential gradient under the patch. These results suggest the use of caution when passive electrodes are present, for example, when a patient receives a nonthoracotomy defibrillator system while epicardial electrodes from a previously implanted system are left in place.
本研究旨在评估被动“旁观者”心外膜电极对除颤效果的影响。
我们假设，放置在内膜电极电击低电位梯度区域的非活性心外膜贴片可能通过其对电击场和潜在电位梯度的影响来影响除颤效果。
我们研究了一块18平方厘米的非活性钛网贴片置于左心室前外侧心外膜上对50%成功除颤概率的影响。在心室颤动电诱导后10秒，通过上腔静脉和右心室导管电极之间施加持续时间均为6毫秒的双相电击。六只狗接受了有或无贴片置于心脏上的上下除颤方案随机分组。
心脏上有导电贴片时，能量的平均50%（±）概率点翻倍，从8.0±3.2焦耳增至16.8±7.0焦耳（p<0.01），前沿电压从334±64伏增至477±98伏（p<0.01）。在另外六只狗中使用非导电贴片作为对照组重复该操作时，能量和前沿电压的平均50%概率点没有显著变化。在盐水饱和泡沫模型中，贴片周围和下方电极的测量显示，导电贴片下方泡沫中的电位梯度平均降低了72%。
被动除颤器贴片可能通过降低贴片下方的电位梯度，显著增加除颤所需能量。这些结果表明，当存在被动电极时需谨慎使用，例如，当患者接受非开胸除颤器系统而先前植入系统的心外膜电极仍留在原位时。
