Estimation of cardiac action potentials wavefronts

A new method for time delay estimation based on the principle of constraint minimization is presented. Classical techniques of time delay estimation use the cross-correlation function or the generalized cross-correlation function where the signals are pre-filtered. In order to improve the result of the multiple time delay estimation between many signals, the principle of constraint minimization is examined. This constraint ensures that the relations between all the time delays among a large number of signals are respected. This new method is applied to cardiac action potentials recorded using the experimental technique of optical fluorescence imaging. Electrical activation wavefronts and propagation delays generated in experimental studies on sheets of cardiac tissue are analyzed.