Lux R L, Fuller M S, MacLeod R S, Ershler P R, Green L S, Taccardi B
Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City 84112, USA.
J Electrocardiol. 1998;30 Suppl:176-80. doi: 10.1016/s0022-0736(98)80071-x.
The QT interval (QTI) has long been useful as a clinical index of the duration of ventricular repolarization, particularly as a marker of prolonged repolarization and its well-established association with arrhythmogenic cardiac states. Likewise, inhomogeneity (dispersion) of repolarization has been linked definitively to increased susceptibility to reentrant arrhythmias. Recent studies have reported the use of QTI dispersion as a meaningful clinical index to identify patients at risk, but the interpretation of the measurement has been controversial. A Langendorff-perfused, isolated canine heart suspended in a torso-shaped, electrolytic tank filled with NaCl-sucrose solution was used to investigate the relationship between body surface QTIs and ventricular repolarization measured directly from the cardiac surface by using activation-recovery intervals, which have been documented to reflect the duration of local action potentials as well as local refractory periods. The data showed poor correlation between cardiac surface activation-recovery intervals and QTIs, as well as the insensitivity of QTIs to regional repolarization shortening in the presence of prolonged repolarization elsewhere. Furthermore, the data confirmed that torso tank QTI dispersion does not reflect directly the full range of measured ventricular repolarization inhomogeneity. It is concluded that body surface QTI dispersion is not a reliable index of repolarization dispersion.
QT间期（QTI）长期以来一直作为心室复极持续时间的临床指标，尤其是作为复极延长及其与致心律失常心脏状态的既定关联的标志物。同样，复极的不均匀性（离散度）已明确与折返性心律失常的易感性增加有关。最近的研究报告称，使用QTI离散度作为识别高危患者的有意义的临床指标，但该测量结果的解释一直存在争议。使用置于装满氯化钠 - 蔗糖溶液的躯干形状电解槽中的Langendorff灌注离体犬心脏，通过使用激活 - 恢复间期来研究体表QTI与直接从心脏表面测量的心室复极之间的关系，激活 - 恢复间期已被证明可反映局部动作电位的持续时间以及局部不应期。数据显示心脏表面激活 - 恢复间期与QTI之间相关性较差，并且在其他部位存在复极延长的情况下，QTI对局部复极缩短不敏感。此外，数据证实躯干槽QTI离散度并不能直接反映所测量的心室复极不均匀性的全部范围。得出的结论是，体表QTI离散度不是复极离散度的可靠指标。
