Local velocity vector fields describing the propagation of epicardial electrical activity were estimated using a new automated method. The method relies on fitting polynomial surfaces to the space-time coordinates of cardiac activity and analytically computing derivatives. The direction and speed of propagation were found during sinus rhythm, pacing, and ventricular fibrillation (VF) in pigs using data from a 21 × 24 array of epicardial electrodes. The results are displayed as vector fields and are used to characterize propagation quantitatively during episodes of complex VF.
