Figure 5.

Experimental demonstration of spatial differences in duration of repolarization. Upper panel shows transmural heterogeneity of action potential durations using color codes in bradycardia and d-sotalol administration mimicking decreased repolarization reserve in the canine wedge long QT syndrome 2 model. Optical action potentials are shown from selected transmural sites (A–D) on lower panel. Arrows denote the significant differences in the action potential duration within relatively short transmural distances. EPI, epicardium; ENDO, endocardium. Adapted from Akar et al. (2002), with permission.