不同起搏部位对正常人体心肌复极离散的影响

目的 :观察正常人心脏不同部位或 2个部位同时起搏时的电生理及心室肌复极差异的变化。方法 :15例接受射频消融术后的患者 ,常规检查排除器质性心脏病。经冠状静脉窦将 1根标测电极送至左心室表面静脉分支 ,另 1根Pacing MAP电极送达右室心尖部 ,记录局部单向动作电位 (MAP)。分别起搏左心室心外膜、右心室心内膜及上述两部位同时起搏 ,行S1S1、S1S2 程序刺激。记录测量QRS波时限、QT间期、Tp Te 间期、MAP时程 (MAPD)等指标及心律失常事件。结果 :体表心电图上QT间期、Tp Te 间期在左室心外膜起搏 (376 .2 6ms、12 2 .5 9ms)、双心室起搏 (36 6 .4 2ms、12 4 .2 3ms)明显较右心室心内膜起搏 (349.33ms、10 4 .14ms)延长 (P <0 .0 1) ,伴有右室心尖部局部MAPD的相应变化。在相同总阵次的程序刺激中 ,左室心外膜起搏与双心室起搏时的室性心律失常多于右室心内膜起搏时 (P <0 .0 5 )。结论 :左室心外膜参与起搏后可能会增大心室肌的跨室壁复极差异 ,伴有复极时间的延长 ,从而使室性心律失常易于发生。

Influence on myocardial repolarization dispersion when pacing at different site in normal individuals

Objective:To investigate the changes of myocardial electrophysiological characters and repolarization dispersion when pacing at different sites of heart in normal individuals. Method:Fifteen patients without structural heart diseases were examined after they were successfully performed RFCA for SVT. Two electrodes were located at right ventricular apex endocardium (RV-Endo) and left ventricular epicardium (LV-Epi) retrograde through coronary sinus, similar to the process of ventricular resynchronization therapy to the congestive heart failure patients in clinic. Programmed S 1S 1 and S 1S 2 stimuli were sent out from RV-Endo, LV-Epi and both of them (biventricular, BiV). 12-lead ECG, MAP (monophasic action potential) of RV-Endo were recorded synchronizedly and all the ventricular arrhythmia events were caculated. Result:QT, T p-T e (T wave peak to T wave end) interval when pacing at LV-Epi ( 376.26 ms, 122.59 ms) and BiV ( 366.42 ms, 124.23 ms) were much longer than that when pacing at RV-Endo ( 349.33 ms, 104.14 ms), with the corresponding changes of MAP duration (MAPD) at RV-Endo. In total 330 episodes of program stimuli in 15 patients, there are more ventricular prematures (VPs) and ventricular tachycardias (VTs) during LV-Epi and BiV pacing than that during RV-Endo pacing.Conclusion:LV-Epi and BiV pacing might result in enlargement of transmural dispersion of myocardial repolarization shown as the changes of QT and T p-T e intervals, which lead to more frequent ventricular arrhythmia events. This finding should be considered seriously when evaluating the long term effect of resynchronization therapy in congestive heart failure patients.