Fig. 1.

Optical mapping and signal analysis. A: schematic of RH237 fluorescence image acquisition showing excitation and emission wavelengths, the location of the pacing electrode, and LV epicardial region that was mapped. B: illustration of beat analysis for the last five beats of each PCL within the dynamic pacing protocol. After signal measurement for each pixel, per-pixel means were computed from the last four beats. Global means were then computed from per-pixel means. C: APD₆₀ vs. DI dispersion analysis diagrams. Left: scatterplot showing APD₆₀ vs. DI at one PCL and the predicted relationship PCL = APD + DI (blue dotted line). APD₆₀ vs. DI radial distance (black arrow) and radial angle (θ) were measured to quantify the location of each pixel’s APD₆₀ vs. DI point from the global mean APD₆₀ vs. DI restitution point (large filled circle). Middle: scatterplot showing low APD₆₀ vs. DI dispersion (top), with most points falling along the predicted line. Radial distance vs. radial angle plots of low APD₆₀ vs. DI dispersion (bottom) have most points falling within 10° segments centered at 135° (crosses) and 315° (open circles). Right: scatterplot showing high APD₆₀ vs. DI dispersion (top), with many points falling off the predicted line. Radial distance vs. radial angle plots of high APD₆₀ vs. DI dispersion (bottom) have many points falling between 135° and 315°. APD₆₀, action potential duration at 60% repolarization; DI, diastolic interval; LV, left ventricular; PCL, pacing cycle length.