正中神经刺激抑制异丙肾上腺素诱发的室性心律失常

Median Nerve Stimulation Inhibits Vntricular Arrhythmias Induced by Isoproterenol Infusion in Dogs

目的探讨正中神经刺激(MNS)对于异丙肾上腺素诱导的室性心律失常(VAs)的影响。方法杂种犬20只,随机分至对照组和正中神经刺激组[迷走神经切断组(MNS-a,n=7);迷走神经不切断组(MNS-b,n=7)]。静脉注射异丙肾上腺素诱发VAs,诱发失败者异丙肾上腺素联合程序刺激再次诱发。每只犬诱发4次心律失常事件,第3次室性心律失常诱发前10分钟接受MNS,持续25分钟。事件结束20分钟后切断MNS-a组双侧迷走神经,再次诱发室性心律失常事件。结果 MNS降低VAs发生率,延迟首次室性心律失常事件出现的时间,延长心室有效不应期。双侧迷走神经切除不影响MNS对于VAs的抑制作用。结论 MNS延长心室有效不应期,抑制VAs发生率,该抑制作用与迷走神经无关。

Objective Cardiac autonomic nervous system（CANS） played an important role in the occurrence of ventricular arrhythmias. Sympathetic hyperactivity or hyperinnervation tends to dispose to ventricular arrhythmias. Somatic nerve stimulation could modulate the activity of CANS and inhibit the occurrence of ventricular arrhythmias. We hypothesized that median nerve stimulation（MNS） decrease the incidence of ventricular arrhythmias induced by isoproterenol infusion. Methods 20 anesthetized mongrel dogs were instrumented to measure heart rate and blood pressure. Ventricular arrhythmias were induced by intravenous isoproterenol [0.6mg/mg/（kg.min）], 5 minutes）, if no ventricular arrhythmias induced, isoproterenol [0.6 mg/mg/（kg.min）] with programmed stimulation was used to induce ventricular arrhythmias again. Each dog underwent four induction episodes and dogs were divided into two groups： the MNS group（n=14, MNS during the third and fourth induction episode） which included two subgroups, MNS-a subgroup with bilateral vagus nerve dissected after the third induction episode（n=7） and MNS-b subgroup with bilateral vagus nerve preserved during the whole experiment process（n=7）; and the control group（n=6） with four repetitive ventricular arrhythmias induction. Median nerve was stimulated 10 minutes before the third and fourth VAs induction episode and lasted 25 minutes. Ventricular effective refractory period was determined by PS before and during MNS. Results MNS reduced the number of arrhythmic beats compared with induction episode in MNS group and control group（p0.05）, and postponed the occurrence time of first arrhythmic beat（p0.05）. MNS prolonged ventricular effective refractory period（p0.05）. Concurrent MNS made the changing of HR tend to smoothing, and the occurrence time of maximum HR was postponed after isoproterenol infusion（p0.05）. The inhibitory effect of MNS on VAs was not affected after bilateral vagotomy（p0.05）. Conclusions MNS prolonged ventricular effective refractory period and decreased the incidence of isoproterenol induced VAs in normal dogs, and this inhibitory effect was not affected by the vagus nerve.