Inherent dispersion in restitution properties over space.

Cardiac tissue heterogeneities can result in spatially dependent restitution properties. We propose a method for quantifying the dispersed nature of these restitution curves (RCs) over a large number of imaged pixels/locations. Cardiac propagation in response to point stimulation was recorded in cardiomyocyte monolayers with voltage-sensitive dye over a large field of view using high resolution imaging. When examining restitution properties of cardiac tissue, the probabilistic nature of these relationships was observed even for macroscopically homogeneous tissue. The method outlined here allows for comprehensive quantification of restitution over space, and the degree of dispersion may provide information complementary to traditional parameters used to predict propensity to arrhythmias such as RC steepness and diastolic interval range.