电磁场与自主神经介导犬心房颤动的相关性研究

摘要

目的 研究旨在观察电磁场对窦性心率、房室传导和心房颤动(房颤)的影响.方法 将犬迷走神经干置于0.043 kHz(2.87 μG,n=5)和2 kHz(0.34 μG,n=6)的电磁场,以频率20 Hz、脉宽0.1 ms、刺激电压范围为1～8 V刺激迷走神经干,观察基础状态、迷走神经干刺激和暴露电磁场2～3 h刺激迷走神经干时的心率、房室传导阻滞(AVB)和房颤诱发率变化.结果 暴露0.043 kHz(2.87 μG)电磁场下,刺激迷走神经干5 min后心率下降达29%(P=0.03),引起AVB的电压下降了60%,AVB诱发增加了5%(P=0.005),该效应持续2～3 h.暴露2 kHz(0.34 μG)电磁场5 min,刺激迷走神经干显著增加房性早搏、房性心动过速和房颤的发生.普萘洛尔和阿托品将植物神经阻滞,不再诱发房性心律失常,但再次暴露迷走神经干于2 kHz(0.34 μG)电磁场又可引起房颤.结论 电磁场有减慢窦性心率、减慢房室传导的作用,0.043 kHz(2.87 μG)电磁场抑制房颤的发生,2 kHz(0.34 μG)电磁场又可引起房颤.提示电磁场通过植物神经介导了房颤的发生和维持,0.043 kHz (2.87 μG) 电磁场具有干预治疗房颤的潜在功效.%Objective To observe the maximal heart rate changes, atrioventricular (A-V) conduction block and atrial fibrillation (AF) inducibility in dogs with vagosympathetic trunk exposed to electromagnetic fields (EMFs). Methods The vagosympathetic trunk of adult dogs was separatedand exposed to EMFs 0.043 kHz(2.87 μG, n=5) and to EMFs 2 kHz(0.34 μG, n=6) for two to three hours. Simultaneously, the vagosympathetic trunk was stimulated with 20 Hz frequency and 1-8 V intensity for 0.1 ms. Heart rate, presence of A-V conduction block and AF inducibility were determined. Results After 5-minutes exposure to EMFs 0.043 kHz (2.87 μG), the maximal heart rate decreased 29%, the voltage applied to vagosympathetic trunk required to induce A-V conduction block decreased by 60% in experimental group versus 5% increase in control group. This effect lasted 2 to 3 hours.While vagosympathetic trunk exposure to EMFs 2 kHz (0.34 μG) was associated with significant increase in the incidence of atrial premature beats, atrial tachycardia and AF, these effects could be blocked by propranolol and atropine. Conclusions Our results showed that 0.043 kHz (2.87 μG) EMFs exposure might reduce while 2 kHz(0.34 μG) EMFs exposure might increase AF inducibility. Our study thus suggested autonomic nervous system of dogs could be affected by EMFs exposure and 0.043 kHz (2.87 μG) EMFs exposure might be a novel option for AF prevention.