Fig. 3

The estimation of action potential characteristics from optical signals is feasible. a Comparison of signal trajectories between optical recordings and microelectrode recordings. The left panel shows a representative activation map of the SAN, on which simultaneous optical and microelectrode recordings were performed. Action potentials recorded intracellularly and optically at positions a–e are shown in the right panel. Isochrones were calculated at 2-ms intervals from the leading pacemaker site. The crista terminalis is delineated by the dashed line. IVC Inferior vena cava, SVC superior vena cava, SEP internal septum, RA right atrium, CT crista terminalis. b Correlation between parameter values of electrically and optically recorded action potentials. The dotted line in the APD50 panels is the line of identity