【摘要】 目的探讨肥厚左心室跨壁复极离散度变化及室性心律失常发生机制。方法制作压力超负荷兔模型,分别记录对照组、肥厚组心室肌内、外膜动作电位并同步记录跨室壁心电图,比较两组动作电位时限(APD90)、跨心室壁复极离散度(TDR)和室性心律失常发生率、尖端扭转性室性心动过速(Tdp)危险度评分。结果(1)与对照组相比,肥厚组内、外膜APD90显著延长,以内膜层心肌更为明显;TDR显著增大(P<0.01);上述变化呈现显著慢频率依赖性;(2)肥厚组室性心律失常发生率、Tdp危险度评分明显高于对照组。结论动作电位时限延长、跨心室壁复极离散度增大基础上的早期后除极和跨室壁折返激动是肥厚心室心律失常的主要机制。更多还原

【Abstract】 Objective To study the variation of transmural dispersion of repolarization(TDR)in hypertrophied left ventricles induced by chronic pressure over-load and probe the underlying mechanism of ventricular arrhythmia.Methods The left ventricular hypertrophy was realized by chronic pressure over-load with the method of abdominal aorta partial ligation at the proximal site 5-10 mm away from the left renal artery for 10 weeks.The transmural ECG and action potentials in endocardium,epicardium of arterially perfused left ventricular preparations of control and LVH groups were recorded simultaneously,and the action potential duration(APD),TDR,ratio of on-set of ventricular arrhythmia,risk score of torsade de pointes(Tdp)in the 2 groups were compared as well.Results(1)Compared with control group,APD_ 90 of endocardium,and epicardium in left ventricular preparations in LVH group were significantly prolonged,especially in the endocardium,and this results in the amplification of TDR(P<0.01).The above results were magnified with the decrease of stimulus frequency.(2)The ratio of ventricular arrhythmia,and risk score of Tdp in LVH group were much higher than those in control group;most of ventricular arrhythmia was closely correlated with transmural reentry triggered by early after-depolarization(EAD)generated from endocardium.Conclusions The ratio of ventricular arrhythmia in LVH myocardium is much higher than that in normal myocardium;EAD and transmural reentry based on the prolongation of APD,amplification of TDR are one of the main mechanisms underlying ventricular arrhythmia.更多还原