di Bernardo D, Langley P, Murray A
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, United Kingdom.
Pacing Clin Electrophysiol. 2000 Sep;23(9):1392-6. doi: 10.1111/j.1540-8159.2000.tb00968.x.
QT interval dispersion may provide little information about repolarization dispersion. Some clinical measurements demonstrate an association between high QT interval dispersion and high morbidity and mortality, but what is being measured is not clear. This study was designed to help resolve this dilemma. We compared the association between different clinical measures of QT interval dispersion and the ECG lead amplitudes derived from a heart vector model of repolarization with no repolarization dispersion whatsoever. We compared our clinical QT interval dispersion data obtained from 25 subjects without cardiac disease with similar data from published studies, and correlated these QT dispersion results with the distribution of lead amplitudes derived from the projection of the heart vector onto the body surface during repolarization. Published results were available for mean relative QT intervals and mean differences from the maximum QT interval. The leads were derived from Uijen and Dower lead vector data. Using the Uijen lead vector data, the correlation between measurements of dispersion and derived lead amplitudes ranged from 0.78 to 0.99 for limb leads, and using the Dower values ranged from 0.81 to 0.94 for the precordial leads. These results show a clear association between the measured QT interval dispersion and the variation in ECG lead amplitudes derived from a simple heart vector model of repolarization with no regional information. Therefore, measured QT dispersion is related mostly to a projection effect and is not a true measure of repolarization dispersion. Our existing interpretation of QT dispersion must be reexamined, and other measurements that provide true repolarization dispersion data investigated.
QT间期离散度可能几乎无法提供有关复极离散度的信息。一些临床测量表明高QT间期离散度与高发病率和死亡率之间存在关联，但所测量的内容尚不清楚。本研究旨在帮助解决这一困境。我们比较了QT间期离散度的不同临床测量值与源自无任何复极离散度的复极心脏向量模型的心电图导联振幅之间的关联。我们将从25名无心脏病受试者获得的临床QT间期离散度数据与已发表研究中的类似数据进行了比较，并将这些QT离散度结果与复极期间心脏向量投射到体表所得到的导联振幅分布进行了关联。已发表的结果包括平均相对QT间期以及与最大QT间期的平均差值。这些导联源自于Uijen和Dower导联向量数据。使用Uijen导联向量数据时，肢体导联的离散度测量值与导出的导联振幅之间的相关性范围为0.78至0.99，而使用Dower值时，胸前导联的相关性范围为0.81至0.94。这些结果表明，所测量的QT间期离散度与源自无区域信息的简单复极心脏向量模型的心电图导联振幅变化之间存在明显关联。因此，所测量的QT离散度主要与投影效应有关，并非复极离散度的真实测量指标。我们对QT离散度的现有解释必须重新审视，并且要研究能够提供真实复极离散度数据的其他测量方法。
