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Figure  4: Sprouting of a broken excitation wavefront for the guinea-pig ventricular model with low excitability (gNa =0.3mS). The solid line corresponds to the V = -10 mV isoline and the dashed one to the tip trajectory (intersection of V = -10 mV and f = 0.5 isolines). In the second frame of plot (a) the cut excitation-wave is shown. This was obtained by stimulating at the bottom of the medium and after the wavefront propagated for awhile setting 2/3 of the left side of the medium to the resting state. Snapshots in (a) are shown every 50ms (left to right starting from top left). In plot (b) the same simulation is shown starting from the time the wavefront was cut with successive frames shown every 10ms. The medium size is 20 mm×40 mm.