How disruption of endo-epicardial electrical connections enhances endo-epicardial conduction during atrial fibrillation.
Loss of side-to-side electrical connections between atrial muscle bundles is thought to underlie conduction disturbances predisposing to atrial fibrillation (AF). Putatively, disruption of electrical connections occurs not only within the epicardial layer but also between the epicardial layer and the endocardial bundle network, thus impeding transmural conductions (‘breakthroughs’). However, both clinical and experimental studies have shown an enhancement of breakthroughs during later stages of AF. We tested the hypothesis that endo-epicardial uncoupling enhances endo-epicardial electrical dyssynchrony, breakthrough rate (BTR), and AF stability.



In a novel dual-layer computer model of the human atria, 100% connectivity between the two layers served as healthy control. Atrial structural remodelling was simulated by reducing the number of connections between the layers from 96 to 6 randomly chosen locations. With progressive elimination of connections, AF stability increased. Reduction in the number of connections from 96 to 24 resulted in an increase in endo-epicardial dyssynchrony from 6.6 ± 1.9 to 24.6 ± 1.3%, with a concomitant increase in BTR. A further reduction to 12 and 6 resulted in more pronounced endo-epicardial dyssynchrony of 34.4 ± 1.15 and 40.2 ± 0.52% but with BTR reduction. This biphasic relationship between endo-epicardial coupling and BTR was found independently from whether AF was maintained by re-entry or by ectopic focal discharges.



Loss of endo-epicardial coupling increases AF stability. There is a biphasic relation between endo-epicardial coupling and BTR. While at high degrees of endo-epicardial connectivity, the BTR is limited by the endo-epicardial synchronicity, at low degrees of connectivity, it is limited by the number of endo-epicardial connections.
Department of Physiology and Maastricht Centre of Systems Biology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands.
Ali
A
Gharaviri
Department of Physiology and Maastricht Centre of Systems Biology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands.
Sander
S
Verheule
Department of Physiology and Maastricht Centre of Systems Biology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands.|Department of Internal Medicine, University Hospital Basel, Basel, Switzerland
Jens
J
Eckstein
Department of Biomedical Engineering, Maastricht University, Maastricht, The Netherlands.|Institute of Computational Science, Faculty of Informatics, Università della Svizzera italiana, Lugano, Switzerland
Mark
M
Potse
Department of Physiology and Maastricht Centre of Systems Biology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands.
Pawel
P
Kuklik
Department of Biomedical Engineering, Maastricht University, Maastricht, The Netherlands.
Nico H L
NH
Kuijpers
Department of Physiology and Maastricht Centre of Systems Biology, Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands.
Ulrich
U
Schotten
D001281:Atrial Fibrillation / Q000503:physiopathology*; D064752:Atrial Remodeling / Q000502:physiology*; D003198:Computer Simulation; D004699:Endocardium / Q000503:physiopathology*; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008955:Models, Cardiovascular; D010496:Pericardium / Q000503:physiopathology*