心房颤动时山羊肺静脉反复快速激动形成原因的研究

The mechanism of pulmonary vein repetitive rapid activation during persistent atrial fibrillation in goats

目的利用心房颤动（房颤）山羊模型探讨肺静脉局部反复快速激动（repetitive rapid activations，RRA）的产生机理。方法在8只山羊的左心房（LA）游离壁外膜和左上肺静脉（LSPV）根部缝合电极片，利用自制的房颤刺激器于体外发放50Hz的冲动刺激左心房，刺激时限1s，每次问隔2s，在（9．3±4．6）d（6～16d）内诱发出自发维持时间超过24h的持续性房颤。分析窦性心律下以及左心房起搏时肺静脉电位（PVP）的特点以及房颤持续过程中RRA的变化。结果在窦性心律时PVP不明显，左心房刺激可显示出PVP，随着基础刺激周长的缩短，LA-PVP的间距加大，PVP间出现分裂，并可诱发房颤。房颤刚发作时的肺静脉电图形态，与心房快速刺激时一致。在房颤刚被诱发时，肺静脉就可出现短暂的局部的RRA，但在房颤时限中所占的比例很低，为3．3％±4．0％。随着刺激时间／房颤持续时间的延长，RRA的比例逐渐增加；在房颤持续24h后，肺静脉RRA的持续时间占总激动时间的91．8％±6．7％（P〈0．05）。结论在本模型肺静脉RRA的产生与其复杂的组织结构有关，而与局部自律性增高和触发激动无关。房颤逐渐稳定过程中，RRA的比例增加与心房／肺静脉的电重构进展有关。

Objective To investigate the mechanism of pulmonary vein repetitive rapid activation （RRA） during persistent atrial fibrillation （AF）. Methods Ten female goats were instrumented with epieardial electrodes patches on the left atrium （LA） free wall and the roots of left superior pulmonary vein （LSPV） and left inferior pulmonary vein （LIPV）. AF was induced and maintained by a home-made stimulator with frequency of 50Hz, duration of 1 second and 2 seconds intermission. The epieardial atrial electrograms at LSPV and LIPV were analysed during sinus rhythm, LA pacing and AF. Results Eight goats finished the study. Persistent AF （〉24h） could be induced in all the 8 goats within 6 to 16 days. In sinus rhythm, pulmonary vein potential （PVP） could not be detected, it was unmasked by LA pacing. With the increase of pacing rate, PVP became fractionated and AF could be induced. The PV elelctrograms just after AF was induced, were almost the same as rapid LA pacing,but RRA was short lasted,it occupied 3.3%±4.0% of AF duration. And when AF lasted for 24 hours, it was 91.8%±6.7% （P 〈 0.05）. Conclusion In this AF model, the complex anatomic structure of pulmonary vein attribute to the occurrence of RRA, the enhanced automaticity and triggered activity may not play an important role.