Phase-specific alternans magnitudes, AD, measured during control-off and control-on conditions. Measurements are from equally spaced locations from the control channel (distances = 0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 cm). (a) Results from all experiment trials (# of preparations = 6, n = 17 total trials). (b) Representative spatial dynamics results demonstrating effect of control. Control-off:control-on pairings – concordant:concordant (preparation #3: BCL = 420 ms); concordant:discordant (preparation #5: BCL = 400 ms); discordant:discordant (preparation #6: BCL = 390 ms). Open-arrows: control-off; closed-arrows: control-on.