An index of organization of the right atrium during atrial fibrillation: Effects of internal cardioversion

Aim of this study is to investigate the effects of unsuccessful internal cardioversions on the propagation of the depolarization wavefronts in the right atrium during atrial fibrillation, by using an index of organization of endoatrial signals (electrograms). The organization was estimated by computing the percentage of points laying on the signal baseline (i.e., number of occurrences, NO). Electrograms were recorded by using a multipolar basket catheter. NO values were computed on two-second long windows, one just before and five just after unsuccessful shocks. We found that immediately after the shock there was an increase in the organization, which fades within few seconds after the shock delivery. Our data show that the proposed index provides the quantitative assessment of organization in the entire right atrium, and gives experimental support to the hypothesis that unsuccessful shocks cause a widespread extinction of electrical wavefronts, which regenerates after the shock.