title: Initiation of atrial fibrillation by interaction of pacemakers with geometrical constraints.
abstract: Atrial fibrillation (AF) is the most common arrhythmia of the heart in industrialized countries. Its generation and the transitory behavior of paroxysmal AF are still not well understood. In this work we examine the interaction of two activation sources via an isthmus as possible cause for the initiation of fibrillation episodes. For this study, the electrophysiological model of Bueno-Orovio, Cherry and Fenton is adapted to atrial electrophysiology, both for physiological and electrophysiologically remodeled conditions due to AF. We show that the interaction of the pacemakers, combined with the geometrical constraints of the isthmus, can produce fibrillatory-type irregularities, which we quantify by the loss of spatial phase coherence in the transmembrane voltage. Transitions to irregular behavior occur when the frequencies of the pacemakers exceed certain thresholds, suggesting that AF episodes are initiated by frequency changes of the activating sources (sinus node, ectopic focus).
authors.affiliation: Institut für Chemie und Biotechnik, Technische Universität Ilmenau, 98684 Ilmenau, Germany. Electronic address: claudia.lenk@tu-ilmenau.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lenk
authors.affiliation: Institut für Biomedizinische Technik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Weber
authors.affiliation: Institut für Biomedizinische Technik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bauer
authors.affiliation: Fachbereich Physik, Universität Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Einax
authors.affiliation: Fachbereich Physik, Universität Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Maass
authors.affiliation: Institut für Biomedizinische Technik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Seeman
mesh_terms: D000200:Action Potentials; D001281:Atrial Fibrillation / Q000473:pathology* / Q000503:physiopathology*; D002304:Cardiac Pacing, Artificial; D003198:Computer Simulation; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D008955:Models, Cardiovascular; D012032:Refractory Period, Electrophysiological; D013997:Time Factors
keywords: Atrial electrophysiology; Obstacle-induced instability; Pacemaker interaction; Paroxysmal atrial fibrillation; Synchronization