Figure 5. Activation sequence and distribution of the safety factor in tissue with a linear gradient of membrane excitability.
Tissue with linear maximum sodium conductance (gNa) gradients parallel (A, C) and perpendicular (B, D) to the direction of propagation are used to explore wavefront curvature evolving in response to uniform and non-uniform dispersion of the source-sink relationship. Excitation waves were generated in an isotropic tissue with the maximum sodium conductance (gNa) linearly varying from 30% to 100% of the control value along the y (A and C) or x (B and D) axis (as indicated by the red arrows) stimulated with a 10 mm×0.1 mm electrode (white colored) at the center of the tissue. Activation sequences are represented by isochrones (black lines, numbers indicate the instant of activation in ms) and the safety factor is color-coded in all panels. Bottom panels are zooms of top panels. Tissue boundaries were not shown for the sake of clarity.