迷走神经对心房电生理特性的调节在犬心房电重构中的变化

The changes of vagal modulation to atrial in atria remodeling in dogs

目的研究迷走神经对心房电生理特性的调节在心房电重构中的变化。方法成年杂种犬9只,麻醉后分离双侧颈部交感-迷走神经干。给予美托洛尔阻断交感神经的影响。在右心房(RA)、冠状静脉窦(CS)和右心室(RV)放置多极导管。消融希氏束完全阻断房室结并植入右室临时起搏器。通过RA导管进行600次/min的起搏30min构建急性心房电重构模型。在心房电重构前后测量基础状态(无迷走神经刺激)和迷走神经刺激下的心房有效不应期(ERP)和房颤易感窗口(VW)。结果在基础状态下,ERP在心房电重构后明显缩短(P<0.05)。迷走神经刺激下,ERP在心房电重构后也明显缩短(P<0.05)。基础状态下,在心房电重构前后均不能诱发房颤(VW接近0)。迷走神经刺激时,房颤易感窗口在心房电重构后明显增大(P<0.05)。结论短期的心房电重构能够缩短心房的有效不应期。心房电重构伴随着迷走神经对心房电生理特性的调节发生改变,导致迷走神经介导性房颤的易感性增加。

Objective Purpose Atrialremodeling takes an important role in perpetuation of atrial fibrillation. Vagal has a close relationship with atrial fibrillation. However, little is known about the relationship between the vagal modulation to atria and atrial remodeling. This study aimed to investigate the changes of vagal modulation to atria in atrial remodeling in dogs. Methods Nine adult mongrel dogs under general anesthesia were involved in this study. Bilateral cervical sympathovagal trunks were deeentrated. Metoprolol was given to block sympathetic effects. Multipolar catheters were placed into right atria （RA） ,coronary sinus（CS） and right ventricle（RV）. Complete atrioventrieular node block was a-chieved by His bundle ablation and temporary RV pacing was applied through RV catheter. Atrial remodeling was performed by 600bpm pacing through RA catheter for 30 minutes. Atrial effective refractory period （ERP） and vulnerability window（VW） of atrial fibrillation were measured with and without vagal stimulation before and after atrial remodeling. Results ERP decreased at baseline after atrial remodling（97.78±16.41 vs 85.56±15.90 ms, P=0.005 at CS; 100±20.62 vs 82.22±19.86 ms, P=0.021 at RA）. ERP during vagal stimulation decreased after atrial re- modeling（48.89±32.96 vs 28.89±16.16 ms, P=0.034 at CS; 48.89±29.34 vs 25.56±8.82 ms, P=0.053at RA）. Atrial fibrillation could not be induced at baseline（ VW close to 0 ） before and after atrial remodeling. Atrial fibrillation VW during vagal stimulation increased signif- icantly after atrial remodeling（24.44±23.51 vs 52.22±23.80 ms, P=0.009 at CS ; 23.33±19.36 vs 38.89±13.97 ms, P=0.0007 at RA）. Conclusion Short - term atrial remodeling can decrease the atrial effective refractory period. Atrial remodeling eompanys with the changes of vagal modulation to atria, thereby increases the susceptibility to atrial fibrillation mediated by vagal.