QT离散度不能反映心肌复极的区域性差异

QT dispersion does not reflect regional heterogeneity of ventricular repolarization

目的 探讨体表心电图上QT离散度 (QTd)是否可以反映区域性的心肌复极差异。方法 正常对照 (对照 )组和心肌梗死 (心梗 )组各有 12 0例 ,记录同步 12导联心电图 ,人工测量各导联QT间期 ,计算QTd。结果 与对照组相比 ,心梗组QTd明显增加 ,分别为 (5 6 3± 17 8)ms与 (10 0 9±5 4 3)ms,P <0 0 0 1;但两组之间存在很大交叉 ,无法确立参考值。最长QT和最短QT在两组的导联分布呈现一致趋势。心梗组全部 12导联QT间期均较对照组明显延长 ,平均QT间期分别为 (397 0± 4 6 8)ms与 (36 7 3± 2 2 8)ms ,P <0 0 0 1。不同梗死部位各亚组之间心电图各导联QT间期均值差异无显著性(P =0 6 36 ) ,未见到与梗死部位相关的区域性QT间期改变。结论 QTd增大常与QT间期延长同时出现 ,QTd增大从整体上反映了心肌复极异常 ,但是不能代表心肌复极的区域性差异。

Objective The original concept of QT dispersion (QTd) as a direct measurement of regional differences in ventricular repolarization is suspected now.Patients with myocardial infarction (MI) were selected to detect the relationship between QTd and obvious regional myocardial disease. Methods The 12-lead synchrony electrocardiograms in 120 healthy people [(37.1±10.8 )years, 82 males and 38 females] and 120 patients [(62.3±10.2) years, 91 males and 29 females] with MI were recorded at 25 mm/s.QT interval was measured by one independent observer with a caliper and QT dispersion was derived. Results QTd was greater in patients with MI than in healthy subjects, but substantial overlapping [(100.9±54.3) ms vs (56.3±17.8) ms,P<0.001] was observed.QT interval was also greater in MI group than in control group [(397.0±46.8) ms vs (367.3±22.8) ms, P<0.001].QTmax and QTmin were equally distributed in leads V 2, V 3, V 4 and aVL, V 1, respectively in both groups. QT intervals were prolonged in all 12 leads in MI group in stead of any regional prolongation.QT intervals were not significantly different among subgroups with different MI location (P=0.636).Conclusion QT dispersion is not an expression of regional heterogeneity of ventricular repolarization, and only an imprecise measurement reflecting repolarization abnormalities.