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Instability of repolarization in LQTS mutation carriers compared to healthy control subjects assessed by vectorcardiography
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
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2013 (English)In: Heart Rhythm, ISSN 1547-5271, Vol. 10, no 8, 1169-1175 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND Potassium channel dysfunction in congenital and acquired forms of long QT syndrome types 1 and 2 (LQT1 and LQT2) increases the beat-to-beat variability of the (IT interval. OBJECTIVE To study about the little known variability (instability) of other aspects of ventricular repolarization (VR) in humans by using vectorcardiography. METHODS Beat-to-beat analysis was performed regarding vectorcardiography derived RR, QRS, and QT intervals, as well as T vector- and T vector loop-based parameters during 1-minute recordings of uninterrupted sinus rhythm at rest in 41 adult LQT1 (n = 31) and LQT2 (n = 10) mutation carriers and 41 age- and sex-matched control subjects. The short-term variability for each parameter, describing the mean orthogonal distance to the line of identity on the Poincare plot, was calculated. RESULTS Mutation carriers showed significantly larger (by a factor 2) instability in most VR parameters compared to controls despite higher instantaneous heart rate variability (STVRR) in the control group. The longer the (IT interval, the greater was its instability, and the instability of VR dispersion measures. CONCLUSIONS A greater instability of most aspects of VR already at rest seems to be a salient feature in both LQT1 and LQT2, which might pave the way for early afterdepolarizations and torsades de pointes ventricular tachycardia. In contrast, no signs of increased VR dispersion per se were observed in mutation carriers.

Place, publisher, year, edition, pages
2013. Vol. 10, no 8, 1169-1175 p.
Keyword [en]
Long QT syndrome, Repolarization, Short-term variability, Vectorcardiography, the amplitude of the maximum T vector in space, T peak to T end, the last part of the QT interval and final repolarization in the 3-dimensional QRST complex
National Category
Cardiac and Cardiovascular Systems
URN: urn:nbn:se:umu:diva-80441DOI: 10.1016/j.hrthm.2013.05.001ISI: 000323492700014OAI: diva2:698291
Available from: 2014-02-21 Created: 2013-09-17 Last updated: 2014-05-07Bibliographically approved

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Diamant, Ulla-BrittJensen, Steen M.
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