title: Nonlinear dynamics in cardiology.
abstract: The dynamics of many cardiac arrhythmias, as well as the nature of transitions between different heart rhythms, have long been considered evidence of nonlinear phenomena playing a direct role in cardiac arrhythmogenesis. In most types of cardiac disease, the pathology develops slowly and gradually, often over many years. In contrast, arrhythmias often occur suddenly. In nonlinear systems, sudden changes in qualitative dynamics can, counterintuitively, result from a gradual change in a system parameter-this is known as a bifurcation. Here, we review how nonlinearities in cardiac electrophysiology influence normal and abnormal rhythms and how bifurcations change the dynamics. In particular, we focus on the many recent developments in computational modeling at the cellular level that are focused on intracellular calcium dynamics. We discuss two areas where recent experimental and modeling work has suggested the importance of nonlinearities in calcium dynamics: repolarization alternans and pacemaker cell automaticity.
authors.affiliation: Greenberg Division of Cardiology, Department of Medicine, Weill Cornell Medical College, New York, New York 10065, USA. trk2002@med.cornell.edu
authors.forename: Trine
authors.initials: T
authors.lastname: Krogh-Madsen
authors.forename: David J
authors.initials: DJ
authors.lastname: Christini
mesh_terms: D000200:Action Potentials; D001145:Arrhythmias, Cardiac; D001698:Biomedical Engineering / Q000379:methods; D002118:Calcium / Q000378:metabolism; D002309:Cardiology / Q000379:methods* / Q000639:trends; D004594:Electrophysiology / Q000379:methods; D006321:Heart / Q000502:physiology; D006329:Heart Conduction System; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D009991:Oscillometry / Q000379:methods; D049490:Systems Biology
chemical_list: D002118:Calcium