title: Impact of tissue geometry on simulated cholinergic atrial fibrillation: a modeling study.
abstract: Atrial fibrillation (AF), arising in the cardiac atria, is a common cardiac rhythm disorder that is incompletely understood. Numerous characteristics of the atrial tissue are thought to play a role in the maintenance of AF. Most traditional theoretical models of AF have considered the atrium to be a flat two-dimensional sheet. Here, we analyzed the relationship between atrial geometry, substrate size, and AF persistence, in a mathematical model involving heterogeneity. Spatially periodic properties were created by variations in times required for reactivation due to periodic acetylcholine concentration [ACh] distribution. The differences in AF maintenance between the sheet and the cylinder geometry are found for intermediate gradients of inexcitable time (intermediate [ACh]). The maximum difference in AF maintenance between geometry decreases with increasing tissue size, down to zero for a substrate of dimensions 20 × 10 cm. Generators have the tendency to be anchored to the regions of longer inexcitable period (low [ACh]). The differences in AF maintenance between geometries correlate with situations of moderate anchoring for which rotor-core drifts between low-[ACh] regions occur, favoring generator disappearance. The drift of generators increases their probability of disappearance at the tissue borders, resulting in a decreased maintenance rate in the sheet due to the higher number of no-flux boundaries. These interactions between biological variables and the role of geometry must be considered when selecting an appropriate model for AF in intact hearts.
authors: Department of Physiology and Institute of Biomedical Engineering, Université de Montréal, Montreal, Quebec, Canada. philippe.comtois@umontreal.ca
authors: Philippe
authors: P
authors: Comtois
authors: Stanley
authors: S
authors: Nattel
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D001281:Atrial Fibrillation / Q000473:pathology*; D018678:Cholinergic Agents / Q000494:pharmacology*; D003198:Computer Simulation; D006325:Heart Atria / Q000473:pathology*; D008955:Models, Cardiovascular
chemical_list: D018678:Cholinergic Agents; D000109:Acetylcholine