刺激左右颈部迷走神经干对犬心脏变时与变传导效应的影响及差异

Effect of Stimulating Left and Right Cervical Vago-Sympathetic Nerves on Cardiac Chronotropic and Dromotropic Function in Dogs

目的:研究犬左右颈迷走交感神经干对心脏变时与变传导效应的影响及差异。方法:Mongrel杂种犬20只,静脉麻醉后,气管插管。分别在左右股动、静脉置入电极导管,监测犬血压、体温及心内电图并记录体表心电图;分离并暴露双侧颈迷走交感神经干,植入高频刺激电极,以不同电压强度刺激左右迷走交感神经干,测量心率、AH间期、心房颤动时心室率的变化。结果:刺激左右颈迷走交感神经干均可使窦性心率降低、AH间期延长、心房颤动时心室率减慢,且至0.6 V时均达到差异具有统计学意义(P<0.01);随刺激电流强度的增加,窦性心率进一步下降、AH间期总体呈延长趋势、心室率总体呈减慢趋势;在同一刺激电流强度下,当刺激电流达到一定强度(1.5 V)时,右侧迷走交感神经干刺激减慢窦性心率的程度显著大于左侧(P<0.01),但刺激左右两侧迷走交感神经干所引起AH间期延长与发生房室传导阻滞的数目及心室率减慢程度差异无统计学意义。结论:颈迷走交感神经干对心脏变时与变传导功能的调节属于双侧支配,其中窦房结的变时功能以右侧调节为优势,房室结的变传导功能则受双侧的均衡支配。

Objective： The purpose of this study was to investigate the effect of stimulating left and right cervical vago-sympathetic nerves on cardiac chronotropic and dromotropie function in dogs. Methods ： Twenty Mongrel dogs were anesthetized and intubated. Electrical catheters were inserted into both femoral arteries and both femoral veins to monitor blond pressure, central body temperature, and to record intracardiac electrogram fl＇om right atrium and His bundle, respectively. Body surface electrocardiogram was also recorded. Bilateral cervical vago-sympathetic nerves were disassociated, exposed and stimnlated by different intensity of high-frequeney current, Sinus rate from right atrium electrogram, AH interval from His bundle eleetrogram and ventricular rate during atrial fibrillation from body surface electrogram were measured. Resuhs： Slowed sinus rate, prolonged AH interval, and slowed ventricular rate during atrial fibrillation were observed by stimulating left and right cervical vago-synlpathetic nerves. And the changes of these indexes were getting significant when stimu- lating voltage was increased to 0.6V（P 〈 0. 01 ） ;with increasing of stimulating voltage, more remarkable lowed sinus rate, pro-longed AH interval and slowed ventricular rate during atrial fibrillation were observed, With the same stimulating voltage, the slowing effects of sinus rate by stimulating right vago-sympathetic nerve was more predominant than that by stimulating left vago-sym-pathetic nerve when stimulating voltage reached ≥ 1.5V（P〈0.01）. However, no significant difference was observed in AH pro-longation, the number of dogs with atrioventricular conduction block and the slowing degree of ventricular rate during atrial fibrillation between stimulating right and left vago-sympathetic nerves. Conclusion： Effect of cervical vago-sympathetic nerves on cardiac chronotropic and dromotropic function was bilaterally regulated. Chronotropic effect of sinoatrial node was predominantly regulated by right cervical vago-sympa-thetic nerve while dromotropic effect of atrioventricular node was equilibrately regulated by both right and left cervical vago-sympathetic nerve.