A QUANTITATIVE FRAMEWORK FOR ANALYZING EPICARDIAL ACTIVATION PATTERNSDURING VENTRICULAR-FIBRILLATION

Few techniques have been developed for deriving quantitative measures of activation patterns during ventricular fibrillation (VF). Such meas ures have many potential applications, for example, assessing the effe cts of time, drugs, or electrical interventions. We have developed a n ew framework for quantifying VF patterns as mapped from an array of si milar to 500 unipolar electrodes. Individual activation wavefronts are isolated from one another using an algorithm that groups together adj acent active electrogram samples (dV/dt < -0.5 V/sec). Contacts betwee n wavefronts are detected; these include fractionations, in which a si ngle wavefront breaks into multiple wavefronts, and collisions, in whi ch multiple wavefronts coalesce to form a new wavefront. The timing an d contact relationships between wavefronts are summarized as a directe d graph. From this model of the VF episode, we derive several paramete rs: number of wavefronts, number of fractionations, number of collisio ns, mean wavefront size, mean area swept out, and mean duration. As an example of this analysis, we computed these parameters in six open-ch est pigs at 5, 10, 15, and 20 sec after electrical induction of VF. Th e number of wavefronts and the number of collisions decreased, whereas the mean wavefront size and mean area swept out increased during this period. These results are consistent with previous studies showing a recovery of organization during the first minute of VF.