The effect of spatial dispersion of recovery on propagation direction during atrial fibrillation

We hypothesized that propagation direction (PD) during atrial fibrillation (AF) is related consistently to gradient of 90% action potential duration (APD90). Monophasic action potentials (MAPs) were recorded at 250 sites from the endocardium of acetylcholine (ACh) perfused canine right atria during pacing. The APD90 field and its gradient were computed from MAP waveforms. Two-dimensional velocity vector fields were estimated from epicardial mapping data acquired during ACh mediated AF. Average PD vector fields were compared to vector fields of APD90 gradient. In 27 episodes of AF, the relationship between PD and APD90 gradient was no different from that of an equal number of uniformly random vectors. However, the curl of PD was higher at sites of large APD90 gradients. Methods were validated in 2-D simulations.