冠心病患者平板运动负荷试验中的QT间期滞后现象

目的观察冠心病患者在平板运动负荷试验中的QT问期滞后现象。方法收集21例经冠状动脉造影确诊的冠心病患者（冠心病组）和20例健康志愿者（对照组）。分析两组的平板运动负荷试验心电图，每份心电图测量50个点的RR间期、QTp间期（Q波起始到T波顶峰的时间）和QTe间期（Q波起始到T波终末的时间），采用Bazett公式[QTc=QT／（RR）”。]计算QTpc间期及QTec间期。以RR间期为横坐标，QTp问期、QTe问期、QTpc问期或QTec问期为纵坐标，作散点图及曲线。比较RR问期为600、550、500、450、400ms时，运动期QTp间期、QTe问期、QTpc间期或QTec间期与恢复期的差异。结果对照组运动期和恢复期的QT／RR曲线几乎重叠；冠心病组运动期和恢复期的QT／RR曲线在RR间期500～600ms段明显分离，恢复期低于运动期。对照组在各RR问期下，运动期QT间期和QTc问期与恢复期的差异无统计学意义（P〉0．05）。冠心病组在RR问期为550、500、450ms时，运动期QTp问期和QTpc间期显著高于恢复期（P〈0．05）；在RR问期为550、500ms时，运动期QTe间期和QTec间期显著高于恢复期（P〈0．05）。结论冠心病患在平板运动负荷试验中有明显的QT滞后现象，后者可能在冠心病的早期无创检测中发挥一定作用。

QT interval hysteresis in the treadmill exercise testing in patients with coronary heart disease

Objective To observe the QT interval hysteresis phenomenon in treadmill exercise testing in patients with coronary heart disease (CHD).Methods Twenty-one patients with CHD,which were diagnosed based on their coronary artery angiography,were enrolled as CHD group.Twenty healthy people were enrolled as control group (con).All subjects underwent treadmill exercise test according to Bruce protocol For each recording,50 points were selected for the RR,QTp(from the onset of QRS to the peak of T wave),and QTe(from the onset of QRS to the end of T wave)interval measurement.Rate corrected QTp(QTpc) and QTe (QTec) were calculated using Bazett formula[ QTc =QT/( RR ) 1/2 ].QTp,QTe,QTpc and QTec interval were plotted against corresponding RR interval,respectively.The difference in QTp,QTe,QTpc and QTec were compared between exercise and recovery period,under RR interval of 600 ms,550 ms,500 ms,450 ms,and 400ms.Results In control group,the QT/RR curve of recovery period nearly overlapped with exercise period.In CHD group,the QT/RR curve of recovery period separated downward from exercise period at the region of RR interval from 500 ms to 600 ms.In control group,there were no significant difference in QTp,QTe,QTpc and QTec between exercise and recovery period under any same RR interval ( P＞0.05 ).In CHD group,QTp and QTpc of exercise period was significant higher than that in recovery period under RR interval of 550 ms,500 ms,and 450 ms( P＜0.05 ),QTe and QTec of exercise period was significant higher than that in recovery period under RR interval of 550 ms,and 500 ms(P＜0.05).Conclusion In treadmill exercise testing,patients with CHD showed overt QT interval hysteresis phenomenon.The QT hysteresis might serve as a useful non-invasive tool in the early detection of patients with CHD.