Rearrangement of Atrial Bundle Architecture and Consequent Changes in Anisotropy of Conduction Constitute the 3-Dimensional Substrate for Atrial Fibrillation

Abstract

During AF, atrial bundle rearrangement manifests itself in more perpendicular orientation of epicardial to endocardial bundles. Propagation of fibrillation waves is dominated by endocardial bundles in acute AF and by epicardial bundles in persistent AF. Together with the loss of endo-epicardial electrical connections, rearrangement of atrial bundles underlies endo-epicardial dissociation of electrical activity and the development of a 3-dimensional AF substrate.