犬在体心肌跨室壁复极不均一性的实验研究

The study of repolarization heterogeneity across ventricular wall in intact canine

目的 :探讨犬在体心肌是否存在跨室壁复极不均一性。方法 :40 %的甲醛溶液 0 1～ 0 3ml注入房室结 ,制备完全性房室传导阻滞模型 ,心室起搏控制心室率。应用单相动作电位记录技术 ,同步记录犬在体心外膜 (epi cardium ,Epi)、中层 (midmyocardium ,Mid)及心内膜 (endocardium ,Endo)心肌单相动作电位 (MAP) ,测量单相动作电位时程 (MAPD)并比较其差异。结果 :在心动周期 (cyclelength ,CL) 30 0ms时 ,Epi、Mid、Endo的MAPD90 分别为 2 0 8 6 7± 44 37ms、2 0 9 17± 38 6 2ms、2 0 3 5 0± 33 84ms(n =10 ) ,在体三层心肌单相动作电位时程无明显差异 ,CL增加至2 0 0 0ms时 ,三层心肌MAPD呈慢频率依赖性延长 ,Epi、Mid、Endo的MAPD90 分别为 32 9 90± 31 90ms、36 9 90±35 0 9ms、317 2 0± 40 2 7ms ,其中Mid的MAPD90 延长最为显著 ,与Epi及Endo相比 ,差异有显著性意义 (P <0 0 5 )。结论

Objective: To investigate the repolarization heterogeneity across the ventricular wall of canine in vivo.Methods:The complete AV block was produced by injection of 0.1 to 0.3 ml of 40% formaldehyde into the AV node, the ventricular rate was controlled by electrical stimulation.With the MAP (monophasic action potential) recording teclmique,MAP of Epi(epicardium),Mid(midmyocardium) and Endo(endocardium) were recorded simultaneously in canine in vivo under different rate of ventricular stimulation, MAPD(monophasic action potential duration) was measured and analysed.Results: The difference of MAPDs between the three layers of ventricular myocardium were not significant at a cycle length(CL) of 300 ms, the MAPD 90 in Epi,Mid and Endo was 208 67±44.37 ms,209.17±38.62 ms,203.50±33.84 ms respectively.When CL was increased to 2 000 ms.MAPDs prolonged low rate dependently in all three layers.MAPD 90 in Epi,Mid and Endo was 329.90±31.90 ms,369 90±35.09 ms,317 20±40 27 ms respectively, MAPD 90 of Mid cells was longer significantly than that of Epi or Endo( P <0 05).Conclusion: There is low rate dependently repolarization heterogeneity in the three layers of ventricular myocardium in canine in vivo.