Objective To investigate the effects of low-level carotid baroreceptor stimulation ( LL-CBS) on isoproter-enol-induced ventricular arrhythmias ( VAs) .Methods Twenty adult mongrel dogs were randomly divided into the LL-CBS group (n=10) and the control group (n=10).The stimulating electrode of carotid artery was placed to monitor the blood pressure ( BP) and heart rate ( HR) .After 1 hour of LL-CBS the VAs was induced by isoproterenol in the LL-CBS group.The stimulation was not stopped until the experiment was over .The false LL-CBS was given to the dogs in the con-trol group.The ventricular effective refractory period ( ERP) during baseline and 1 hour.Each dog underwent three in-duction episodes.The occurrence time of first arrhythmic beat, the number of ventricular premature beat, the number and the duration of ventricular tachycardia were measured and analyzed .Results The values of BP and HR were not signifi-cantly different between the two groups during baseline , 1 hour and intravenous isoproterenol ( all P>0 .05 ) .The ERP was (165 ±5) ms in the LL-CBS group and (168 ±8) ms in the control group during baseline (P>0.05), and the ERP was respectively (181 ±7) ms and (162 ±7) ms in the LL-CBS group and control group 1 hour after stimulation (P<0.05).The occurrence of VAs in the LL-CBS group was less than that in the control group every time (all P<0.05).The occurrence time of first ventricular premature beat of the LL-CBS group was 341 (512, 224) s, and 215 (327, 90) s in the control group;the number of premature ventricular contractions was 52 (83, 20), and 107 (162, 54) in the control group;and the number of ventricular tachycardia was 2.3 (6.7, 0.5), and 5.5 (9.3, 2.4) in the control group (all P<0.05).Conclusion LL-CBS inhibits the occurrence of isoproterenol-induced VAs without chan-ges of BP and HR .%目的：探讨低强度颈动脉压力感受器刺激（LL-CBS）对异丙肾上腺素诱导的室性心律失常（VAs）的影响。方法正常成年杂种犬20只，随机分为对照组和LL-CBS组各10只，均安置颈动脉窦刺激电极，监测血压、心率。 LL-CBS组于VAs诱发前1 h开始LL-CBS直至实验结束，对照组给予假性LL-CBS，分别测量基线时和刺激1 h后心室有效不应期（ ERP）。心室ERP测量结束后，保持颈动脉窦刺激，静置半小时，静脉注射异丙肾上腺素，诱发3个VAs事件。分别记录3个VAs事件时VAs发生次数，首个室性早搏出现的时间、室性早搏次数、室性心动过速（简称室速）次数及持续时间。结果两组在基线状态、刺激1h和注射异丙肾上腺素后血压、心率比较均无统计学差异（P均＞0．05）。 LL-CBS组、对照组基线时心室ERP分别为（165±5）、（168±8）ms（P＞0．05），刺激1 h时分别为（181±7）、（162±7）ms（P＜0．05）。在3个VAs事件过程中，LL-CBS组发生Vas次数均少于对照组（P均＜0．05）；LL-CBS组首次室性早搏出现的时间为刺激后341（512，224） s、对照组为刺激后215（327，90） s，室性早搏次数分别为52（83，20）、107（162，54）次，室速次数分别为2．3（6．7，0．5）、5．5（9．3，2．4）次，两组比较P均＜0．05。结论 LL-CBS刺激可抑制异丙肾上腺素诱发的VAs发生，且不影响血压、心率。
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