Repolarization features as detectable from electrograms and electrocardiograms

This contribution discusses the feasibility of extracting the major features of repolarization: its spatio-temporal behaviour, and how much of its global or local behaviour might be deduced from signals that can be observed experimentally. The analysis presented is based on source-volume-conductor configurations ranging from the classic cable theory, with sources derived from reaction diffusion computations, to a realistic thorax model comprising a whole heart model with electric sources represented by the equivalent electric double layer. The analysis focuses on the fact that the local activation recovery interval (ARI) at regions activated by expanding wave fronts is significantly longer than those activated by contracting ones. The consequences of this effect on observed magnitude and wave form of recorded signals are illustrated.