中文摘要：

目的在迷走神经介导性心房颤动（房颤）和6h快速起搏介导的房颤模型中研究心房动作电位时限（APD）的回复性质。方法18只犬随机分为迷走神经介导性房颤组（A组，／7,=8）和6h快速起搏介导性房颤组（B组，n=10）。两组犬麻醉后开胸，暴露心脏，分别在多个肺静脉及心房部位记录单相APD。以APD复极90％（APD。）的时间为纵坐标、以其前的舒张问期为横坐标构建不同部位的APD回复曲线。结果在A组，迷走神经刺激显著缩短每一部位的APD。、使回复曲线变平坦（斜率〈1）并抑制APD交替的发生，但同时迷走神经刺激增加房颤的诱发性和持续时问[（13_＋3）s对（5＋1）S，P〈0．05]。在B组，6h快速起搏缩短APD、使回复曲线变陡峭（斜率〉1）并促进APD交替的发生，同时房颤的发生率和持续时间增加[（10~3）s对（5±1）8，P〈0．osj。结论迷走神经介导性房颤和6h快速起搏介导的房颤具有不同的回复性质，提示不同机制的房颤具有不同的心房回复性质。

英文摘要：

This study sought to investigate the artrial action potential duration（APD） restitution properties in two different atrial fibrillation（AF） models： vagally mediated AF and 6 h rapid atrial pacinginduced AF. Methods Eighteen anaesthetized openchest dogs were assigned in Group A, vagally mediated AF （n = 8 ） or Group B ,6 h rapid atrialpacinginduced AF （n = l0 ）. In both groups, the monophasic action potential was subsequently recorded at multiple pulmonary vein and atrial sites. The APD restitution curve was constructed using a dynamic pacing protocol and determined by plotting each APD90 against the preceding diastolic interval at incremental atrial pacing rates at eight sites. Results In Group A,vagal stimulation significantly shortened the APDg0 ,flattened the APD restitution curve （slopes〈l）, and suppressed the APD alternans at each site, while increasing the AF inducibility and duration （P〈O. 05 for all）. In Group B ,6 h rapidpacinginduced APD shortening, steepened the restitution curves （slopes〉 1 ）, facilitated the APD alternans, and also increased the incidence and duration of AF （ P〈0. 05 for all）. Conclusion This study showed distinct atrial APD restitution properties in vagally mediated AF and 6 h rapid pacinginduced AF,indicating specific restitution kinetics in different mechanisms of AF.