Figure 6.

Optical determination of the second identified mechanism, which was only observed in 1 s pulses (0.25 mW mm-2, highlighted in blue). Here the locally stable spiral activity (image sequence I) is disrupted by the illumination resulting in extrusion of the arrhythmic wave pattern to the boundaries (image sequence II). Already during photostimulation the sinus rhythm resets (image sequence III) and continues after switching off (image sequence IV). The scale-bars indicate 2 mm and are equal for all images in the corresponding panel. Shown are the MAP recording (in red) and optical traces of several local spots on the ventricles (in black, as indicated in panel I). The corresponding movie is available as (Supplementary Material Movie 3).