Aim:To study how the combined use of amiodarone with Ibutilide effects on myocardial transmural dispersion of repolarization (TDR),and whether the combined use of Ibutilide with amioda-rone is able to reduce the side effects compared with the use of Ibutilide alone.Methods:35 New Zeal-and rabbits were randomly divided into control group,Ibutilide group A(perfused with normal tyrode's so-lution containing 2 mg/L Ibutilide ),Ibutilide group B (perfused with hypopotassemia and hypomag-nesemia tyrode's solution containing 2 mg/L Ibutilide),amiodarone (50 mg/kg amiodarone orally given every day for 4 weeks)combined with Ibutilide group A (perfused with normal tyrode's solution contai-ning 2 mg/L Ibutilide),amiodarone (50mg/kg amiodarone orally given every day for 4 weeks )com-bined with Ibutilide group B(perfused with hypopotassemia and hypomagnesemia tyrode's solution contai-ning 2 mg/L Ibutilide),with 7 rabbits in each group.The left ventricular wedge preparations were made for each group.Transmural ECG and action potentials from both endocardium and epicardium were simul-taneously recorded.The changes of TDR and Tdp were analyzed.Results:In this study,TDR level was found to be increased to 50.42 ±4.2 ms in Ibutilide group A and 67.12 ±12.62 ms in Ibutilide group B, significantly higher than the control group.Amiodarone was found to be able to decrease TDR level to 16.8 ±3.3 ms in both amiodarone combined with Ibutilide group A and B.Based on the results,Ibutil-ide was used after the administration of amiodarone,and it was found that TDR level maintained at 27.22 ±5.1 ms in amiodarone combined with Ibutilide group A,and 32.21 ±5.2 ms in amiodarone combined with Ibutilide group B,significantly lower than that of the control group.In the arrhythmias experiment, we observed that arrhythmia occurred significantly less in amiodarone group B(0/7)than Ibutilide group B(5/7).Conclusion:Amiodarone may be given orally for a period of time or up to 4 weeks before Ibutil-ide is given,which can effectively lower the risk of Tdp that might be caused by Ibutilide.This might im-prove the safety of Ibutilide.%目的：研究胺碘酮与伊布利特联合应用对心肌室性心律失常的影响及机制．方法：新西兰大白兔35只，随机分配，分为A组：正常对照组、B组：含伊布利特质量浓度2 mg/L正常台式液灌流、C组：含伊布利特质量浓度2 mg/L低钾低镁台式液灌流、D组：含伊布利特质量浓度2 mg/L正常台式液灌流、E组：含伊布利特质量浓度2 mg/L低钾低镁台式液灌流，每组7只．C组及D组实验前每日称量大白兔体质量，并根据体质量用电子天平称取质量分数50 mg/kg药粉，经灌胃针给予灌胃，每日1次，连续4周．实验时，每组大白兔均在麻醉后制作左室楔形心肌块，经左冠脉开口处灌流，记录内膜及外膜动作电位时程，计算出灌流前后跨壁复极离散（TDR）的改变，后给予程序刺激，观察室性心律失常发生情况．结果：单独使用伊布利特心肌TDR升高为（50.42±4.2）ms，较对照组的（41.7±15.3）ms明显升高（P＜0.05）．单独使用胺碘酮心肌TDR则降低为（16.8±3.3）ms，与对照组比较亦有显著差异．胺碘酮应用后再使用伊布利特心肌TDR改变为（27.22±5.1）ms，同样明显低于对照组TDR．而在低钾低镁环境下，单独使用伊布利特心肌TDR的升高则更为显著，达到（67.21±12.62）ms，而胺碘酮的降低心肌TDR的作用则与正常环境相同，为（16.8±3.3）ms．低钾低镁环境下胺碘酮应用后再使用伊布利特的心肌TDR为（32.21±5.2）ms，仍然明显低于对照组的心肌TDR水平．在观察室性心动过速的实验过程中，口服胺碘酮后再应用伊布利特，无论是在正常台式液环境还是低钾低镁台式液环境下，均无室速的发生，与在低钾低镁情况下单独使用伊布利特组中5只发生室速有明显差异（P＜0.05）．结论：口服胺碘酮后再使用伊布利特，可以减少依布利特单独使用时诱发的室性心律失常．
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