9.2 Data Analysis A. AF initiation will be mapped and transitional mechanisms identified Phase mapping will be used to analyze AF initiation, defined as the first 5 seconds of AF. Biatrial phase movies will be created to visualize spatial distribution of activation times across the LA and RA. These phase movies illustrate the rotor phase singularities, which are defined as the point about which the integral of phase is 0, and visualized as the intersection of depolarization and repolarization isolines.