Multilevel analysis of calcium dynamics in stimulated cultures of cardiomyocytes.

We present an automatic method to characterize calcium activity in a culture of cardiac cells from a sequence of microscopy fluorescence images. The approach quantifies both the response of each individual cell in the culture to external field stimulation and the propagation properties of calcium wave-fronts, thus providing complementary information at different physiological levels. The technique classifies the response of each cell as regular or irregular based on a set of dynamical and morphological features of the calcium transients. Isochronal maps were constructed from the local activation times across the culture, and the front propagation was classified as planar or non-planar. The method has been applied to a set of 35 experiments, and the results indicate a significative connection between irregular behavior at the single-cell level and irregular front propagation.