Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome

Heart Rhythm : the Official Journal of the Heart Rhythm Society
Veronique M F MeijborgRuben Coronel

Abstract

Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood. The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves. We simultaneously recorded surface ECG and unipolar electrograms at baseline and after dofetilide in a canine model of dofetilide-induced LQT2 (6 male mongrel dogs). Standard ECG variables, T-wave duration, and moments of peaks of bifid T waves (Tp1 and Tp2) were correlated with moments of local repolarization. Epicardial electrograms were recorded over the left ventricular (LV) and right ventricular (RV) anterior walls (11 × 11 electrode grid, 5-mm interelectrode distance). In 5 of the 6 hearts, we also recorded intramural unipolar electrograms (n = 4-7 needles per heart). In each unipolar recording, we determined activation time, repolarization time (RTs), and activation-recovery interval. In addition, we studied RT response to heart rate changes. Dofetilide prolonged QT and QTc, induced bifid T waves in 4 of 6 animals, and prolonged RT heterogeneously in LV and RV, resulting in increased interventricular and LV intraventricular RT dispersion. Dofetilide did not induce a disparate response in acti...Continue Reading

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Citations

Jun 5, 2016·Cardiac Electrophysiology Clinics·Fatemah Shenasa, Mohammad Shenasa
May 26, 2016·Progress in Biophysics and Molecular Biology·Bas J BoukensRuben Coronel
Nov 8, 2018·Annals of Noninvasive Electrocardiology : the Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc·Jason A ThomasLarisa G Tereshchenko
Oct 9, 2020·Heart Rhythm : the Official Journal of the Heart Rhythm Society·Mathilde R RivaudRuben Coronel
Oct 29, 2021·Medical & Biological Engineering & Computing·Daniel RomeroAlfredo Hernández

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