Figure 6.

(Top row) Effect of small-scale resistive heterogeneities on the shock-induced ΔV_m distribution on the cut surface of the same wedge as in Fig. 4 for permeable and impermeable boundary conditions (right and left panels, respectively). Middle panel shows a plot of ΔV_m profiles, with and without small-scale heterogeneities, along the centrally located horizontal line (endo- to epicardium) in the middle of the ΔV_m maps. (Bottom row) Optical maps of ΔV_m (ΔV_opt) on the cut surface for permeable and impermeable boundary conditions (right and left panels, respectively). Dotted lines in the maps are zero iso-fluorescence lines. Middle panel shows a plot of ΔV_opt profiles, with and without small-scale heterogeneities, along the centrally located horizontal line (endo- to epicardium) in the middle of the ΔV_opt maps. Optical potentials are normalized as percent of normal action potential magnitude. Shock strength is 28 V/cm; fiber orientation is rotational (as in Fig. 2).