Induced pluripotent stem cell derived cardiomyocytes (iPSC-CM) provide a powerful platform for disease modeling and
drug development in vitro. Traditionally, electrophysiological methods or
fluorescent dyes (e.g.
calcium) have been used in their functional characterization. Recently, video microscopy has enabled non-invasive analysis of CM contractile motion. Simultaneous assessments of motion and
calcium transients have not been generally conducted, as motion detection methods are affected by changing pixel intensities in
calcium imaging. Here, we present for the first time a protocol for simultaneous video-based measurement of contraction and
calcium with
fluorescent dye Fluo-4 videos without corrections, providing data on both ionic and mechanic activity. The method and its accuracy are assessed by measuring the effect of fluorescence and background light on transient widths and contraction velocity amplitudes. We demonstrate the method by showing the contraction-
calcium relation and measuring the transient time intervals in
catecholaminergic polymorphic ventricular tachycardia patient specific iPSC-CMs and healthy controls. Our validation shows that the simultaneous method provides comparable data to combined individual measurements, providing a new tool for measuring CM biomechanics and
calcium simultaneously. Our results with
calcium sensitive
dyes suggest the method could be expanded to use with other fluorescent reporters as well.