迷走神经刺激对犬肺静脉电生理特性的影响

Impact of vagal stimulation on pumonary vein electrophysiological character in dogs and the study on the mechanism of vagal atrial fibrillation

目的通过观察迷走神经刺激前后肺静脉有效不应期(ERP)、ERP离散及ERP频率适应性的变化,探讨迷走神经介导性心房颤动的发病机制。方法健康杂种犬15只,暴露心脏及左上肺静脉,把自制电极置于肺静脉外膜上,在迷走神经刺激前及刺激时分别测量在起搏周长为300ms、200ms时肺静脉长轴上四个部位的ERP,并计算ERP离散及ERP频率适应性。结果迷走神经刺激时肺静脉近端(PV1,8)、中端(PV2,7、PV3,6)的ERP比刺激前显著缩短(P<0.05),ERP频率适应性显著降低,而肺静脉远端(PV4,5)的ERP及ERP频率适应性无明显变化(P>0.05),迷走神经刺激时ERP离散比刺激前显著增加(P<0.05)。结论迷走神经张力升高能显著缩短肺静脉近端、中端的ERP,降低肺静脉近端、中端的ERP频率适应性,显著增加肺静脉ERP离散。

Objective To investigate the mechanism of vagal atrial fibrillation by observing the effect of vagal stimulation on pulmonary vein effective refractory period （ERP） , dispersion of ERP and frequency adaptability of ERP. Methods Fifteen healthy dogs were investigated. The annular electrode was placed in the adventitia of the left superior pulmonary veins（PV）. Four regional ERPs in long axis of PV were measured with the pace cycle length 300 ms and 200 ms before vagus nerve was stimulated. Then these ERPs were measured again when vagus nerve was being stimulated. Dispersion and frequency adaptability of ERP were calculated. Results When vagus nerve was being stimulated, ERPs in PV1,8 , PV2,7 and PV3,6 were shorted strikely（ P 〈 0.05 ） , frequency adaptability of ERP was depressed and dispersion of ERP was enhanced dramatically（ P 〈0.05 ）. However, ERP and frequency adaptability of ERP in PV4,5 appeared no marked change （ P 〉 0.05 ）. Conclusions ERP is shortened and frequency adaptability of ERP is lowered at proximal, midst end of PV and dispersion of ERP also goes up strikingly due to enhanced vagal stress.