FIG. 4.
(Color online) Six selected alternans solutions for a homogeneous fiber of 100 cells with negative Ca→Vm coupling when paced at BCL=375 ms. Panels (a)–(c) are obtained using down-sweep protocols from 500 ms to 375 ms in steps of 1, 2, and 25 ms, respectively. Panels (d)–(f) are obtained by directly pacing at BCL=375 ms with different initial distributions in Cain, see text for details. To verify if a solution reaches steady state, we plot the last 10 beats of the simulation results, where odd beats are represented by red solid lines and even beats by blue dashed lines. The coincidence of all odd beats and that of all even beats confirm that the solution is indeed in steady state.