兔肺静脉心肌袖组织电生理特性研究

Characteristics of electrophysiology in pulmonary vein in rabbit

目的:研究兔肺静脉心肌袖组织的电生理特性,以探讨局灶性房颤起源于肺静脉的电生理基础。方法:台氏液灌流下分离获取30只兔左房及相连肺静脉组织,采用标准玻璃微电极插入标本不同部位,程序刺激下分别记录动作电位并测量各项参数:静息膜电位(RMP)、动作电位幅度(APA)、动作电位复极至50%的时间(APD50)、动作电位复极至90%的时间(APD90)。结果:正常台氏液灌流下,在肺静脉心肌袖的入口处及远端电刺激均可记录到一种快反应动作电位,1期复极迅速,平台期短,形态似三角形。两者的静息电位、APD50比较差异无显著性,APD90近端长于远端,(168.50±36.13)ms∶(142.39±24.46)ms,P<0.05。肺静脉近心端可观察到自发搏动,其自发电位表现为0期除极速度慢,幅度低,频率慢,似存在舒张期除极。以4μmol/L异丙肾上腺素循环灌流后,2例肺静脉心肌袖近端快反应动作电位出现了早期后除极。结论:肺静脉肌袖的自发动作电位、复极异质性,及可由异丙肾上腺素诱发早期后除极等电生理特性,均提示肺静脉可能通过自律性增高、触发活动或微折返诱发局灶性房颤。

Objective：To investigate the electrophysiological characteristics of the myocardial sleeves in pulmonary vein （PV） obtained from healthy rabbits, and tried to find the basis on which ectopie beats and focal atrial fibrillation originated from the PV. Methods：Transmembrane action potential（AP） were recorded in multicellular tissues from multiple sites of PV and LA obtained from 30 healthy adult rabbits by conventional glass microelectrode technique. Results： In normal perfusion, two types of electrical activities were observed, including fast response AP driven by electrical stim- ulation and spontaneous AP. The profile of fast response AP in PV sleeves was similar to that in the atrium, and there were no difference in the parameters of AP between the proximal and distal PVs except AP duration （APD） at 90%（APD50）, which were larger in the proximal than that in the distal end （168.50 36.13ms vs 142.39 24.46ms, P〈0.05）. Perfusion with isoproterenol（Iso）, early afterdepolarization （EAD） developed during phase--3 repolarization of fast respond AP were recorded in the proximal PVs. Conclusion：The characteristics of electrophysiology of PV, including the spontaneous AP, the inhomogeneities of repolarization existed in the PV sleeves, and EAD induced by Iso, indicated that PV may initiate focal atrial fibrillation by enhanced automaticity, triggered activity or micro-re-entry.