Reconstructed three-view maximum intensity projections of (a) Fluo-4-labeled and (b) CMO-labeled cardiomyocytes. (c) The profiles of the calcium sparks along the dashed lines in (d) at t = 5.20 s. (d) The zoom-in time-lapse X′Y and X′Z′ maximum intensity images of the blue square region in (a) showing the calcium sparks in different time frames. The dashed white circles indicate the more distinct calcium spark events. Scale bars, 10 μm. Multimedia views: https://doi.org/10.1063/5.0125946.1; https://doi.org/10.1063/5.0125946.2