Dynamics of sustained reentry in a loop model with discrete gap junction resistances.
The dynamics of reentry is studied in a one-dimensional loop of model cardiac cells with discrete intercellular gap junction resistance (R). Each cell is represented by a continuous cable with ionic current given by a modified Beeler-Reuter formulation. For R below a limiting value, propagation is found to change from period-1 to quasiperiodic (QP) at a critical loop length (L(crit)) that decreases with R. Quasiperiodic reentry exists from L(crit) to a minimum length (L(min)), which also shortens with R. The decrease of L(crit) (R) is not a simple scaling, but the bifurcation can still be predicted from the slope of the restitution curve giving the duration of the action potential as a function of the diastolic interval. However, the shape of the restitution curve changes with R. An increase of R does not seem to increase the number of possible QP solutions since, as in the continuous cable, only two QP modes of propagation were found despite an extensive search through alternative initial conditions.
Chen
Wei
W
Department of Physiology, Institute of Biomedical Engineering, Université de Montréal, Montréal, Canada H4J-1C5. wei.chen@umontreal.ca
Potse
Mark
M
Vinet
Alain
A
D000200:Action Potentials; D000818:Animals; D001703:Biophysics / Q000379:methods*; D002468:Cell Physiological Phenomena; D003198:Computer Simulation; D004553:Electric Conductivity; D020342:Finite Element Analysis; D017629:Gap Junctions; D006321:Heart / Q000502:physiology; D006329:Heart Conduction System; D006801:Humans; D008954:Models, Biological; D008955:Models, Cardiovascular; D008962:Models, Theoretical