应用体表心电图测定QT离散度的错误概念及其理由的探讨

A comment on the incorrectness of the conception using surface ECG to express QT dispersion

目的 自Ｃａｍ ｐｂｅｌｌ等提出ＱＴ离散度（ＱＴｄ）以来，临床上普遍采用，用心电图（ＥＣＧ）来测ＱＴ间期，其有长短，只因心向量（ＶＣＧ）在某个导联轴上的投影量不同所致，并不能代表某局部的ＱＴ间期，因此有必要深入探讨。方法 选择临床诊断明确的数千例同时有ＥＣＧ和ＶＣＧ者，从中选出有ＱＴｄ 异常者（≥５０ ｍ ｓ）和长ＱＴ者１００ 例。结果 １．ＱＴｄ 异常可见于正常人，儿童老年均可。２．ＱＴｄ异常受心率影响很大，心率慢时有异常ＱＴｄ，而心率增快时ＱＴｄ 可转为正常。３．ＱＴｄ 异常与有无恶性室性心律失常无关，而与其ＱＴ 是否延长密切相关。结论 我们认为测量ＱＴ间期并分析其ＥＣＧ 和ＶＣＧ应密切结合临床，目前对ＱＴｄ 的分析应慎重。

Objective QT dispersion (QTd) has been widespread during the recent years since Campbell first put forward this conception.However,the QT interval measured from a particular electrocarioqraphic (ECG) lead,whatever longer or shorter,is depending upon relative quantity of spatial vector force projecting on that lead,and it could not represent the QT interval of the local myocardium the ECG lead is facing.Further investigation is necessary. Method ECG's and vectorcardiograms (VCG) from 100 patients,whose clinical diagnosis had been well documented,were analyzed.All of them had prolonged QT intervals and abnormal QTd's(≥50 ms). Results 1.Abnormal QTd might be encountered in normal persons (including children and elders).2. QTd be influenced by heart rate.Sometimes,QTd was abnormal with a slower heart rate but became normal with a faster heart rate in the same person.3.Abnormality in QTd was not correlated with having malignant arrhythmias or not,but the latter was rather more closely related to the longer QT interval. Conclusion QTd should be looked at and its meaning should be integrated with the clinical background of that particular patient.At present,the QTd should be read with caution,and in the long run,the concept of QTd should be reappraise.QTd is mainly an attribute of T Loop morphology.