迷走神经对犬房室传导的调节作用及Koch三角底部消融对其影响

Vagal modulation on atrioventricular conduction before and after ablation on the bottom of the Koch＇ s triangle

目的迷走神经对房室传导功能有重要的影响，但确切的作用未完全明确。慢径消融能够消除房室传导双径路的现象，而且消融后心房迷走神经张力发生了变化。本实验旨在探讨心房迷走神经对房室传导的调节作用及Koch三角底部消融对其影响。方法11条成年杂种犬，全身麻醉下行颈交感一迷走神经干剥离术并连接神经刺激仪，静脉应用美托洛尔阻断交感神经活性。经右颈内静脉穿刺放置冠状静脉窦导管，经左股静脉穿刺放置高位右心房导管，右股静脉放置希氏束导管，在希氏束至冠状静脉窦口中下1／2的区域行射频消融。测量消融前后基础状态（无迷走神经刺激）以及迷走神经刺激状态下的房室传导不应期，并描记房室传导曲线。取消融区域的心房组织行病理学检查。结果得到7条犬的有效数据。（1）消融前基础状态下房室传导的有效不应期为（165．7±43．1）ms，迷走神经刺激下为（172．9±55．6）ms；消融后基础状态下为（167．1±53．8）ms，迷走神经刺激下为（171．4±59．8）ms。消融前后，迷走神经刺激均导致不应期有所延长，但差异无统计学意义（P〉0．05）。（2）消融前，迷走神经刺激使房室传导时间明显延长，且房室传导曲线出现“纵向分离”现象；消融后，迷走神经刺激及基础状态下房室传导曲线区别不明显，迷走神经刺激导致的房室传导“纵向分离”现象消失。（3）组织学检查证实，Koch三角底部区域有丰富的迷走神经分布，射频消融损伤了该区域的迷走神经。结论一定强度的迷走神经刺激能增加房室传导的纵向分离程度，Koch三角底部区域消融损伤了局部的迷走神经，消除了该区域迷走神经调节作用导致的房室传导功能的变化。

objective The vagal modulation to atrioventricular conduction remains unclear. The vagal modulation effects on atrioventricular nodal reentrant tachycardia could be observed after the slow pathway ablation. This study aimed to investigate the vagal modulation to atrioventricular conduction and the effect of ablation on bottom of Koch＇ s triangle. Methods In 11 dogs, bilateral cervical sympathovagaf trunks were decentralized ,with Metoprolol administrated. Linear lesion was performed from middle area of Koch＇s triangle to the coronary sinus ostium. Before and after ablation, atrioventricular nodal effective refractory period （ERP） and atrio- ventricular conduction curves were measured at baseline and during vagal stimulation. The histological studies were also performed. Results The data from 7 dogs were available. （ 1 ） ERP of atrioventricular conduction prolonged under vagal stimulation before [ （ 165.7±43.1 ） ms vs. （ 172. 9±55.6 ） ms] and after ablation [ （ 167. 1 ±53. 8） ms vs. （ 171.4±59. 8 ） ms ], but without statistic significance （ P 〉 0. 05 ）. （ 2 ） The atrioventricular.conduction time was remarkably prolonged during vagal stimulation before ablation,which means the conduction curve shifted upward and to the right. More important, the curve became discontinuous. （3） The architecture of individual ganglia was significantly altered after ablation. Conclusion Certain strength of vaga/ stimulation could inerease the longitudinal dissociation of the atrioventricular conduction. Radiofrequency ablation did cause the damage of the regional vagal innervation.