Comprehensive Assessment of Cardiac Activation and Repolarization Dynamics by Body Surface Potential Mapping

Several studies emphasize the utility of dynamical heart rate parameters and/or repolarization disparity in the assessment of malignant arrhythmia vulnerability. In this study the spatio-temporal action potential dynamics were assessed by the use of body surface potential map (BSPM) records. Healthy subjects and a group of arrhythmia patients were enrolled in the study. Records were taken with a typical length of 5 minutes. The spatio-temporal nature of activation and repolarization sequence was characterized by QRS and QRST integral and integral difference maps. Furthermore, RR distances, nondipolarity indices (NDI) and the α angle of 192D QRS and QRST vectors were used to assess depolarization and repolarization dynamics. Results revealed that repolarization changes are causally preceded by perturbations in the depolarization process. Substantial non-overlapping information was found in the frequency spectra of the heart rate (RR) parameter and in the spatial activation and repolarization complexity, represented by NDI. Apparently, the diminished effect of respiratory arrhythmia is associated with increased repolarization dispersion. Results on the effect of premature stimuli on the repolarization dispersion show that NDI increases immediately after a single premature stimulus, though in arrhythmia patients significant NDI peaks may occur without premature stimuli as well. K eywords: Repolarization Dynamics, QRS Integral, QRST Integral, Index of Non-Dipolarity, Heart Rate Variability