兔LQT2模型时空复极异质性变化与室性心律失常发生的关系

为探讨心室跨壁复极离散度(TDR)和动作电位时程(APD)恢复性质的变化在LQT2室性心律失常发生中的作用,笔者采用冠状动脉灌注的兔左室肌楔形组织块制备LQT2模型。标本随机分四组:对照组(标准台氏液灌注);LQT2模型(简称模型)组(100μmol/Ld,l-sotalol灌流);模型+低钾(3mmol/L)组和模型+低钾+维拉帕米(2μmol/L)组。观察不同基础周长(BCL)刺激(500,1000和2000ms)条件下,四组标本APD90、TDR和APD恢复性质的变化与室性心律失常发生的关系。结果:①在不同BCL条件下,与对照组相比,模型组、模型+低钾组及模型+低钾+维拉帕米组的内外膜心肌细胞的APD90均增大,以内膜心肌细胞的APD90增大显著,导致TDR增加。②BCL为500和1000ms时,与对照组相比,模型组、模型+低钾组的APD恢复曲线斜率显著增加,而模型+低钾+维拉帕米组,差异无显著性。③在BCL为1000和2000ms时,给予S1S2程序刺激,模型+低钾组尖端扭转性室性心动过速发生率为5/7。结论:TDR增大和APD恢复性质的变化在室性心律失常的发生中均起着重要的作用。

Relationship Between Spatiotemporal Heterogenity of Ventricular Repolarization and Ventricular Arrhythmia in Long QT Syndrome 2 Models

To investigate the role of transmural dispersion of repolarization(TDR) and cardiac restitution properties in arrhythimogeneity in LQT2, we observed the effects of d,l-sotalol, hypokalemia and calcium channel blocker(v erapamil) on TDR and cardiac restitution properties at different basic cycle length(BCL) by using the arterially perfused rabbit left ventricular wedge preparation. Results:Perfused with d,l-sotalol, d,l-sotalol and hypokalemia, d,l-sotalol,hypokalemia and verapamil, APD_ 90 were prolonged in epicardium and endocardium, and specially in endocardium. So TDR was markedly increased. Th e maximum slopes of APD restitution curve was also increased at two different BCL in the p resence of LQT2 model and hypokalemia, verapamil could markedly reduce APD and the maxim um slopes of APD restitution curve. At BCL of 1 000 ms and 2 000 ms in the presence of d,l-sotalol and hypokalemia, Tdp could be induced in 5 of 7 rabbits, whereas no Tdp occurred in the group after verapamil was added. Conclusion: Both TDR and APD restitution properties contribute to arrthymia in LQT2.