Kalman J M, Power J M, Chen J M, Farish S J, Tonkin A M
Department of Cardiology, Austin Hospital, University of Melbourne, Parkville, Victoria, Australia.
J Am Coll Cardiol. 1993 Oct;22(4):1199-206. doi: 10.1016/0735-1097(93)90438-7.
We assessed the feasibility of low energy endocardial defibrillation in a canine model of atrial fibrillation, comparing catheters with large surface area electrodes and standard electrode catheters, and evaluated the effects of lead configuration and circuit impedance on defibrillation energy requirements.
Although recent animal studies have demonstrated the feasibility of low energy endocardial atrial defibrillation, their results have been conflicting with regard to important methodologic aspects.
In 14 anesthetized greyhounds, atrial fibrillation was induced by rapid atrial pacing and maintained by vagal stimulation. Two large surface area braided electrode catheters and two standard electrode catheters were introduced percutaneously, one of each, in the right atrial appendage and right ventricular apex. A cutaneous patch electrode was placed on the left thorax. Biphasic shocks synchronized to the ventricular electrogram were used to terminate atrial fibrillation. Seven configurations were evaluated. Three used standard electrodes: proximal atrial cathode to distal atrial, ventricular or cutaneous anode. Four used braided electrodes: three with atrial cathode to ventricular, cutaneous or combined anode; one with ventricular cathode to atrial anode.
Defibrillation with standard electrode catheters was associated with high impedance (576 +/- 112 omega) and low success rates for all configurations (28% success at < or = 40 J, no successes at 10 J). Low energy defibrillation was readily achieved with the braided electrodes with significantly lower impedance (75 +/- 13 omega, p < 0.0001). Ventricular fibrillation did not occur. The success rate of cardioversion increased in a dose-response manner, allowing fitting of a sigmoid curve and calculation of energy associated with 50% (ED50) and 90% (ED90) success. The most successful configuration was ventricular cathode/atrial anode (ED50 1.5 +/- 0.4 J), and the least successful was atrial anode/cutaneous patch (ED50 6.5 +/- 3.2 J, p = 0.0001).
Low energy atrial defibrillation is feasible using large surface area electrodes but not with standard electrode catheters owing to high impedance. An intracardiac anode provides lower impedance and higher success rates than are provided by a cutaneous anode.
我们评估了在犬类房颤模型中进行低能量心内膜除颤的可行性，比较了具有大表面积电极的导管和标准电极导管，并评估了导联配置和电路阻抗对除颤能量需求的影响。
尽管最近的动物研究已经证明了低能量心内膜房颤除颤的可行性，但在重要的方法学方面，其结果一直存在冲突。
在14只麻醉的灵缇犬中，通过快速心房起搏诱发房颤，并通过迷走神经刺激维持。经皮插入两根大表面积编织电极导管和两根标准电极导管，每侧各一根，分别置于右心耳和右心室心尖。在左胸放置一个皮肤贴片电极。使用与心室电图同步的双相电击来终止房颤。评估了七种配置。三种使用标准电极：近端心房阴极至远端心房、心室或皮肤阳极。四种使用编织电极：三种是心房阴极至心室、皮肤或组合阳极；一种是心室阴极至心房阳极。
使用标准电极导管除颤时，所有配置的阻抗都很高（576±112Ω），成功率很低（≤40J时成功率为28%，10J时无一成功）。使用编织电极很容易实现低能量除颤，其阻抗显著更低（75±13Ω，p<0.0001）。未发生室颤。复律成功率呈剂量反应方式增加，可拟合S形曲线并计算与50%（ED50）和90%（ED90）成功相关的能量。最成功的配置是心室阴极/心房阳极（ED50 1.5±0.4J），最不成功的是心房阳极/皮肤贴片（ED50 6.5±3.2J，p=0.0001）。
使用大表面积电极进行低能量心房除颤是可行的，但由于阻抗高，使用标准电极导管则不可行。心内阳极比皮肤阳极提供更低的阻抗和更高的成功率。
