Oikarinen L, Paavola M, Montonen J, Viitasalo M, Mäkijärvi M, Toivonen L, Katila T
Department of Medicine, Helsinki University Central Hospital, Finland.
Pacing Clin Electrophysiol. 1998 Oct;21(10):1934-42. doi: 10.1111/j.1540-8159.1998.tb00013.x.
QT dispersion is a measure of heterogeneity in ventricular repolarization. Increased ECG QT dispersion is associated with life-threatening ventricular arrhythmias. We studied if magnetocardiographic (MCG) measures of QT dispersion can separate postmyocardial infarction patients with and without susceptibility to sustained VT. Manual dispersion measurements were compared to a newly adapted automatic QT interval analysis method. Ten patients with a history of sustained VT (VT group) and eight patients without ventricular arrhythmias (Controls) were studied after a remote myocardial infarction. Single-channel MCGs were recorded from 42 locations over the frontal chest area and the signals were averaged. QT dispersion was defined as maximum-minimum or standard deviation of measured QT intervals. VT group showed significantly more QT and JT dispersion than Controls. QTapex dispersions were 127 +/- 26 versus 83 +/- 21 ms (P = 0.004) and QTend dispersions 130 +/- 37 versus 82 +/- 37 ms (P = 0.013), respectively. Automatic method gave comparable values. Their relative differences were 9% for QTapex and 27% for QTend dispersion on average. In conclusion, increased MCG QT interval dispersion seems to be associated with a susceptibility to VT in postmyocardial infarction patients. MCG mapping with automated QT interval analysis may provide a user independent method to detect nonhomogeneity in ventricular repolarization.
QT离散度是心室复极异质性的一种度量。心电图QT离散度增加与危及生命的室性心律失常相关。我们研究了QT离散度的磁心动图（MCG）测量方法能否区分有和没有持续性室性心动过速（VT）易感性的心肌梗死后患者。将手动离散度测量结果与一种新采用的自动QT间期分析方法进行比较。对10例有持续性VT病史的患者（VT组）和8例无室性心律失常的患者（对照组）在陈旧性心肌梗死后进行研究。从前胸部区域的42个位置记录单通道MCG，并对信号进行平均。QT离散度定义为测量的QT间期的最大值减去最小值或标准差。VT组的QT和JT离散度显著高于对照组。QTapex离散度分别为127±26毫秒和83±21毫秒（P = 0.004），QTend离散度分别为130±37毫秒和82±37毫秒（P = 0.013）。自动方法得出的数值相当。它们的相对差异平均为QTapex离散度9%，QTend离散度27%。总之，MCG的QT间期离散度增加似乎与心肌梗死后患者的VT易感性相关。采用自动QT间期分析的MCG标测可能提供一种独立于用户的方法来检测心室复极的不均匀性。
