不同起搏部位对正常犬和长QT间期犬模型在体跨心室壁复极离散的影响  

Influence of pacing site on myocardial transmural dispersion of repolarization in normal and long QT dog

作　　者：白融[1] 吕加高[1] 卜军[1] 刘念[1] 周强[1] 阮燕菲[1] 

机构地区：[1]华中科技大学同济医学院附属同济医院心内科,武汉430030

出　　处：《中华心律失常学杂志》2004年第5期278-284,共7页Chinese Journal of Cardiac Arrhythmias

基　　金：国家自然科学基金资助项目(30370573)

摘　　要：目的以正常犬和长QT间期(LQT)犬模型的在体3层心肌单向动作电位时限(MAPD)和跨室壁复极离散(TDR)、体表心电图上QT间期和TpTe间期等为指标,研究不同部位起搏,尤其是左心室外膜参与起搏后心肌复极特性的变化。通过这种模拟临床上心室再同步治疗的方法,旨在观察左心室起搏、双心室起搏是否会增加恶性室性心律失常发生的危险性。方法8只健康成年犬经导管射频消融希氏束制备三度房室阻滞模型。开胸手术后分别在左心室外膜、右心室内膜和双心室起搏时同步记录体表心电图和心内膜下、中层、心外膜下3层心肌的单相动作电位(MAP),测定QT间期、TpTe间期和3层心肌的MAPD、TDR。然后以氯化铯(CsCl)制备LQT犬模型并重复上述实验。结果在正常犬,左心室外膜与双心室起搏后,心内膜下、中层、心外膜下3层心肌的MAPD均有延长,并有TDR的增大(左心室外膜起搏4716ms、双心室起搏3754ms、右心室内膜起搏2675ms,P<0001),体表心电图TpTe间期的变化与之平行。在LQT犬,在CsCl使3层心肌MAPD延长的基础上,左心室外膜参与起搏进一步明显增大TDR,而CsCl增大TDR的作用被掩盖。结论左心室心外膜与双心室起搏后使心内膜下、中层、心外膜下3层心肌的MAPD均延长并使TDR增大,可能成为导致恶性室性心律失常的基础。在临床上推广应用心室再同?Objective Based on the hypothesis that pacing at left ventricular epicardium(LV Epi)or biventricular(BiV,cardiac resynchronization therapy,CRT)unavoidably had influences on the character of myocardial repolarization,the later was known as a high risk factor of malignant ventricular arrhythmias.The purpose of the present study was to examine the changes of QT interval and T p T e interval on surface ECG,monophasic action potential duration(MAPD)of subendocardial,subepicardial,Mid layer myocardium,and myocardial transmural dispersion of repolarization(TDR)on intracardiacelectrogram,when pacing at LV Epi and BiV compared with those pacing at right ventricular endocardium(RV Endo)in normal and Cesium Chloride(CsCl)induced long QT interval(LQT)dog model hearts.Methods Eight normal dogs were performed radiofrequency catheter ablation of his bundle under the guide of X ray fluoroscopy so that we could voluntarily control the heart rate of the animals in the following experiments under the situation of the complete atrioventricular block.After a thoracotomy,ECG and MAP of subendocardial,subepicardial and mid layer myocardium were recorded synchronized when pacing at RV Endo,LV Epi and BiV separately.Then CsCl was given to make LQT dog models and the above experiments were repeated.The TDR was defined as the difference between the longest and shortest MAPD of these three lays of myocardium.The T p T e meant the interval from the peak to the end of T wave,which was a represent index of TDR on surface ECG.ResultsIn normal dogs,pacing participating of LV(LV Epi,BiV)prolonged MAPD of all the subendocardial,subepicardial and mid layer myocardium( P <0 05).At the same time,TDR prolonged from 26 75 ms at RV Endo pacing to 37 54 ms at BiV pacing and to 47 16 ms at LV Epi pacing( P <0 001),with parallel changes of T p T e interval on surface ECG.In LQT dogs,based on the lengthening of subendocardial,subepicardial and mid layer myocardium MAPD,LV Epi and BiV pacing itself rather than the CsCl further increase TDR.ConclusionPacing p

关 键 词：左心室 双心室起搏 心肌 QT间期 心外膜 正常 心内膜 体表心电图 复极离散 起搏部位 

分 类 号：R541.7[医药卫生—心血管疾病]