Figure 9.

Susceptibility to conduction block determined by a tissue expansion model. The critical width (h_c) of a 4-mm-long source strand at which propagation can be maintained in the 4 mm × 4 mm bulk area (see inset in A) was determined at 100%, 70%, and 40% of the maximum sodium channel conductance (g_Na). (A) h_c versus g_Na in control cells (80 μm/20 μm; solid line), long cells (160 μm/20 μm; dashed lines), and wide cells (80 μm/40 μm; dotted lines). Assumption I (g_GJ proportional to A_m) is represented by solid symbols, and assumption II (constant g_GJ) by open symbols. (B) h_c versus g_Na in control cells with normal (solid symbols) or uniform (open symbols) GJ distribution (insets) while lateral g_GJ was 2.6 μS (solid lines) or 13 μS (dashed lines).