A Reduced Differential Model of the Electrical Activity of Cardiac Purkinje Fibres

A reduced order differential model of cardiac Purkinje fibres action potential, with only eight state variables, is presented. Its structure, derived from basic physical principles can be used for the main other cardiac cell types, a useful property for some model-based signal or image processing applications. The electrical activity of cardiac Purkinje fibres is reconstructed using particular values of the parameters. This model of the membrane excitation mechanism and intracellular calcium dynamics describes the principal ionic current underlying autorhythmicity; calcium uptake and release from the sarcoplasmic reticulum; effects of the binding of calcium on myoplasmic proteins which affect the Nernst potential of calcium, and then the membrane potential. The model allows realistic modelling of cardiac Purkinje fibres action potential, total ionic current, CICR dependence on intracellular calcium concentrations. Simulations illustrate the role of the inward sodium current as the dominant mechanism underlying pacemaker depolarization during spontaneous activity