QT interval dispersion: dispersion of ventricular repolarization or dispersion of QT interval?

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...

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Bibliographic Details
Published in:Journal of electrocardiology 1998, Vol.30 Suppl, p.176-180
Main Authors: Lux, R L, Fuller, M S, MacLeod, R S, Ershler, P R, Green, L S, Taccardi, B
Format: Article
Language:English
Subjects:
Action Potentials
Animals
Arrhythmias, Cardiac - physiopathology
Body Surface Potential Mapping
Dogs
Electrocardiography
Electrophysiology
Heart Ventricles - physiopathology
In Vitro Techniques
Pericardium - physiology
Ventricular Function
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Summary: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.
ISSN:0022-0736
DOI:10.1016/S0022-0736(98)80071-X