低钾对扩张型心肌病跨室壁复极不均一性的影响

目的　研究低钾是否为扩张型心肌病 (DCM )发生室性心律失常的重要促发因素及其电生理机制。方法　将家兔随机分成DCM实验组及正常对照组 ,建立DCM家兔模型并进行离体心脏灌流 ,观察低钾时两组之间 3层心肌APD及跨室壁复极离散度 (TDR)的改变。结果　低K+ 灌流时DCM实验组和正常对照组中层心肌细胞单相动作电位复极 90 %时程 (APD90 )、TDR均长于正常K+ 灌流 (P <0 0 0 1) ,但以DCM实验组延长更为明显 (P <0 0 0 1)。结论　低K+ 延长中层心肌细胞APD ,增加跨室壁复极不均一性 ,可能是DCM易发室性心律失常的重要促发因素。

Effects of Hypokalemia on Transmural Heterogeneity of Ventricular Repolarization in Rabbit Models with Dilated Cardiomyopathy

Objective To determine whether hypokalemia plays an important role in the occurrence and its electrophysiological mechanisms of ventricular arrhythmias in rabbit models with dilated cardiomyopathy (DCM). Methods Adriamycin was used to induce rabbit models with DCM. The rabbits were randomly divided into control group and DCM group. The rabbit hearts were perfused with hypokalemic Tyrode's solution in vitro after perfused with normal Tyrode's solution, and the changes of action potential duration at 90 % repolarization (APD 90 ) in three myocardial layers and TDR were observed in both groups. Results APD 90 of midmyocardial cells and TDR were longer in hypokalemic Tyrode's solution perfusion than those in normal Tyrode`s solution perfusion both in DCM group and control group, while prolongation of APD 90 , TDR in DCM group was much more than that in control group ( P <0 001). Conclusion Hypokalemia could increase transmural heterogeneity of ventricular repolarization and prolong APD of midmyocardial cells, and might play an important role in the occurrence of ventricular arrhythmias in rabbits with DCM.