Ventricular repolarization during uni and biventricular pacing in normal subjects

BackgroundThe cardiac depolarization-repolarization process (D-REPP) may differ among various modes of cardiac pacing depending on the paced chamber(s) and lead position. We intended to assess the effect of different modes of cardiac pacing (left, right and biventricular) on the D-REPP as expressed in QRS, QT, peak-to-end of the T wave (PETW) and PETW/QT intervals and their dispersion. These intervals were compared during pacing and sinus rhythm.MethodsWe studied 31 patients without structural heart disease and with normal ventricular function who underwent right, left and biventricular pacing. Simultaneous 12-leads were recorded and electronic calipers were used for measurement of the QRS, QT, corrected QT (cQT), PETW, and PETW/QT ratio.ResultscQT duration, PETW, standard deviation of the PETW, PETW/QT, and QRS duration were shorter during sinus rhythm. Isolated stimulation of the right or the left ventricle produced a similar increase in all the intervals and did not display significant differences in terms of cQT duration, PETW, PETW/QT, or QRS duration. Biventricular pacing produced a significant increase in cQT, QRS, PETW and PETW/QT, but these values were shorter than those obtained during isolated right or left ventricular stimulation.ConclusionIn subjects without structural heart disease, cardiac pacing produces a significant increase of the D-REPP. No differences were found when comparing right or left univentricular pacing. Biventricular stimulation induces less perturbation of the D-REPP.