消融犬Marshall韧带对刺激心房左后脂肪垫所致心房颤动的影响及机制

The impact of ablation of ligament of Marshall on the atrial fibrillation induced by left posterior atrial fat pad stimulation in a canine model

目的探讨消融犬Marshall韧带对刺激心房左后脂肪垫所致心房颤动(简称房颤)的影响及机制。方法成年杂种犬14条,随机分为实验组8条,对照组6条。实验组首先测量左肺静脉和左心耳的有效不应期,继而刺激心房左后脂肪垫诱发房颤。消融Marshall韧带上段后和下段后重复上述步骤。对照组除不干预Marshall韧带外,其它电刺激方案与实验组相同,同时对该组犬的心脏进行迷走神经染色。结果①实验组消融Marshall韧带后,左肺静脉和左心耳的有效不应期均显著延长(P<0.05)。②和消融前比较,实验组消融Marshall韧带上段后的房颤诱发率有下降趋势(70.8%vs87.5%,P>0.05);消融Marshall韧带全程后房颤诱发率显著下降(33.3%,P<0.001)。对照组三次电刺激所测得的不应期和房颤诱发率无差异。③Marshall韧带与左下肺静脉、心房左后脂肪垫、左心耳之间存在迷走神经的直接联系。结论消融犬Marshall韧带可显著降低刺激心房左后脂肪垫所致房颤的诱发率。

Objective To elucidate the impact of ablation of ligament of Marshall （LOM） on atrial fibrillation （AF） inducibility during left posterior atrial fad pad （AFP） stimulation and the underlying mechanisms in a canine model. Methods Fourteen mongrel adult dogs were randomly divided into the experimental group （ n = 8） and the control group （n = 6）. In experimental group, measurement of the effective refractory period （ERP） from the left pulmonary veins （PVs） and left atrial appendage （LAA） followed by AF induction with left posterior AFP stimulation, were conducted be- fore LOM ablation, after superior segmental of LOM ablation and after LOM completely ablation. The same stimulation protocol was also performed, with the same time interval, in the control group, in which LOM was intact. Meanwhile, the distribution of epicardial cholinergic nerve fibers in the lateral left atrium was investigated by acetylcholinesterase staining in the control group. Results ERP of left PVs and LAA was significantly prolonged after LOM ablation in experimental group, as compared with pre-ablation （ P 〈0. 05 ）. Comparing with pre-ablation, destruction of the superior segment of the LOM decreased the AF inducibility from 87.5% to 70.8% （ P 〉0. 05 ）, and completely ablation of LOM further dropped to 33.3 % （P 〈 0. 001 ）. In contrast, ERP and AF inducibility in the control group were not significantly changed. Acetylcholinesterase staining unveiled directly vagal nerve connections among the the region of LOM, left posterior AFP, left inferior PV and LAA. Conclusion LOM ablation can significantly attenuate AF inducibility provoked by left posterior AFP stimulation.