QT间期变化频率依赖性的研究

Insight into the nature and the mechanism underlying the changes of QT interval

目的探讨心电图QT间期变化的本质和内在机理。方法选择24小时动态心电图检出短阵SVT者80例,对比观察因SVT终止发作、RR间期突然跳跃延长时QT间期及其中包含的QRS、JT间期各自不同的变化特征。结果随着RR间期的突然跳跃式延长,QT间期由0.356±0.029增至0.423±0.043s(p<0.001),JT间期由0.264±0.033s增至0.332±0.042s(p<0.001),同时伴有T波的增高增宽(高度由0.272±0.119mV增至0.377±0.146mV,时限由0.211±0.043ms增至0.277±0.062ms,p<0.01)。整个过程中QRS波群时限未见明显变化。结论 JT间期是导致QT间期变化的实质所在,鉴于这一变化对心室储血量具有被动依存特征,而且在时间上又与心室收缩同步共存,提示应当从整体心脏的"机械-电反馈"原理对心电图上的ST段、T波变化从根源上做出相应解释。

Objective To investigate the nature and mechanism underlying the changes of QT interval. Methods 80 consecutive subjects with short run SVT who underwent 24 hour dynamic recordings were selected. QT interval and its containing JT intervals, QRS duration of the sudden prolonged RR interval induced by the termination of SVT were compared with those of the preceding short RR interval. Results The QT and JT intervals were prolonged instantly following the jump of RR interval. QT interval increased from 0.356±0.029 to 0.423±0.043s, and JT interval increased from 0.264 ±0.033 to 0.332 ±0.042s,（both p0.001）, with a simultaneous increase of the amplitude and duration of T waves（the amplitude increased from 0.272±0.119 to 0.377±0.146mV, the duration increased from 0.211±0.043 to 0.277±0.062ms, both p0.01）. The QRS complex remained stable during the whole process. Conclusions JT interval is the primary part that determines the change of QT interval. Based on the fact that the JT interval not only varies passively with the blood volume accumulated in the ventricles, but also coexists with the process of ventricular contraction, a global ＂mechano-electric feedback＂hypothesis was suggested which can give a new interpretation to the morphological changes of ST segment and T wave.