肺静脉隔离对迷走神经功能及心房颤动易感性的影响

目的研究肺静脉隔离(PVI)对犬的心房迷走神经功能及心房颤动(简称房颤)易感性的影响。方法9条成年杂种犬,全麻下行颈交感-迷走神经干剥离术。静脉应用美托洛尔阻断交感神经活性。分别于肺静脉消融前后在基础状态及迷走神经刺激时测量窦性周长(SCL)、右心耳(RAA)、左心耳(LAA)、冠状静脉窦近端(CSp)和冠状静脉窦远端(CSd)的不应期(ERP)及心房易感窗口(VW)。结果①PVI前迷走神经刺激能明显降低SCL(P<0.001),PVI后迷走神经刺激对SCL影响较小(P>0.05)。②PVI前,迷走神经刺激能明显缩短心房各部位ERP(P均<0.05)。PVI后,迷走神经刺激对心房ERP的影响较小(P均>0.05)。③PVI前后基础状态下测得的VW无变化。PVI后迷走神经介导的房颤诱发率明显下降(P均<0.05)。结论PVI能导致迷走神经介导的窦房结抑制、心房不应期缩短能力及房颤易感窗口增加能力明显下降。

Impact of pulmonary vein isolation on vagal activity and vulnerability to atrial fibrillation

Objective To investigate the impact of pulmonary vein isolation(PVI) on vagal modulation to the atria and susceptibility to atrial fibrillation(AF).Methods 9 adult mongrel dogs under general anesthesia were involved in this study.Bilateral cervical sympathovagal trunks were decentralized.Metoprolol was given to block sympathetic effects.Atrial effective refractory period(ERP),vulnerability window(VW)of AF,and sinus rhythm cycle length(SCL) were measured at baseline and during vagal stimulation before and after PVI at RAA,left atrial appendage(LAA),distal coronary sinus(CSd) and paroximal coronary sinus(CSp).Results SCL decreased significantly during vagal stimulation before PVI(P<0.001),while SCL remained unchanged during vagal stimulation after PVI(P>0.05).ERP at baseline increased significantly before PVI compared with that during vagal stimulation(all P<0.05),while ERP remained unchanged after PVI at baseline and during vagal stimulation(all P>0.05).AF was very difficult to be induced at baseline before and after PVI(VW close to 0),while VW of AF to vagal stimulation significantly decreased after PVI(P<0.05).Conclusions The decreased ERP and unchanged SCL to vagal stimulation after PVI indicates that PVI attenuates the vagal modulation to the atria.The decreased VW to AF by PVI indicates that attenuated vagal tone may contribute to the suppression of AF.