Bifurcation Phenomena in Cardiac System: Mechanistic Analyses and Control Design of Automaticity and Arrhythmias
Education and Research
Abstract
The heart is a huge hierarchical complex dynamical system consisting of molecular, cellular, tissue, and organ systems. Therefore, understanding the robustness and fragility of the electrical activity in each system level within the heart will be valuable for establishing a methodology that predicts and prevents the development of heart diseases as system failures. Cardiac arrhythmia is a certain kind of failure of the electrical activity in the heart and has been believed to be evoked by triggered activities following afterdepolarization under certain conditions such as long QT syndrome. Recently, our understanding of the mechanisms for the development of early afterdepolarizations (EADs) has been advanced by combining computer simulations of action potentials (APs) with bifurcation analysis, which is one of the numerical analyses based on dynamical system theory. From the viewpoint of stability changes of APs observed in mathematical ventricular myocyte models, we also found that multi-stable dynamical AP responses occurred under specific attenuating conditions of repolarization currents. In this chapter, we explain the relationships between dynamic responses in the cardiac system as a dynamical system and bifurcation phenomena and introduce the arrhythmogenic responses of cardiomyocytes as a dynamic failure observed in the electrophysiological system.
The heart is a huge hierarchical complex dynamical system consisting of molecular, cellular, tissue, and organ systems. Therefore, understanding the robustness and fragility of the electrical activity in each system level within the heart will be valuable for establishing a methodology that predicts and prevents the development of heart diseases as system failures. Cardiac arrhythmia is a certain kind of failure of the electrical activity in the heart and has been believed to be evoked by triggered activities following afterdepolarization under certain conditions such as long QT syndrome. Recently, our understanding of the mechanisms for the development of early afterdepolarizations (EADs) has been advanced by combining computer simulations of action potentials (APs) with bifurcation analysis, which is one of the numerical analyses based on dynamical system theory. From the viewpoint of stability changes of APs observed in mathematical ventricular myocyte models, we also found that multi-stable dynamical AP responses occurred under specific attenuating conditions of repolarization currents. In this chapter, we explain the relationships between dynamic responses in the cardiac system as a dynamical system and bifurcation phenomena and introduce the arrhythmogenic responses of cardiomyocytes as a dynamic failure observed in the electrophysiological system.