Davy J M, Pons M, Beck L, Messner-Pellenc P
Service de cardiologie B, hôpital Arnaud-de-Villeneuve, CHU de Montpellier.
Arch Mal Coeur Vaiss. 1995 Jan;88 Spec No 1:25-31.
During sinus rhythm, the successive responses to the application of electrical stimuli of increasing intensity during the vulnerable period are cardiac stimulations followed by repetitive ventricular responses and then ventricular fibrillation. An impulse of even greater intensity is not followed by ventricular fibrillation (shock at the upper limit of vulnerability) suggesting that defibrillatory shock is effective only when it does not reinduce fibrillation. Two other hypotheses are also proposed in fibrillation, that of critical mass and that of extension of the refractory periods, in particular after biphasic shocks. Clinically, the measurement of the threshold of defibrillation is difficult as it is a random process which does not obey the all or nothing principle. Ideally, a graph of efficacy versus energy should be constructed but this is only possible under experimental conditions. The effects of different antiarrhythmic drugs have been studied in this manner; in general, the sodium channel blockers improve the energies of defibrillation.
在窦性心律期间，在易损期施加强度递增的电刺激时，相继出现的反应先是心脏刺激，接着是重复性心室反应，然后是心室颤动。强度更大的冲动之后不会出现心室颤动（处于易损性上限的电击），这表明除颤电击仅在不会再次诱发颤动时才有效。关于颤动还提出了另外两个假说，即临界质量假说和不应期延长假说，尤其是在双相电击之后。临床上，除颤阈值的测量很困难，因为这是一个随机过程，不遵循全或无原则。理想情况下，应该绘制疗效与能量的关系图，但这仅在实验条件下才可行。已经以这种方式研究了不同抗心律失常药物的作用；一般来说，钠通道阻滞剂可提高除颤能量。
