The generation and modulation of the heart beat: a phase response curve based model of interacting pacemakers cells

This work introduces a series of simplified computer models for the generation and modulation of the heart beat: from a single pacemaker cell to a large population of pacemakers cells composing the SA node and atria. In the authors' models, the pacemaker cell is characterized by its intrinsic cycle length. The pacemaker interaction with the outside world is characterized by its phase response curve (PRC). The PRC represents the type of coupling to the external stimulus applied to the pacemaker cell. This approach allows one to investigate the behaviour of a pacemaker cell in response to the application of simulated depolarization pulse, to vagal and sympathetic stimulations. The authors qualitatively investigated the phenomena of "accentuated antagonism" between the autonomic branches, and the respiratory sinus arrhythmia. They gained insight into the conditions which predispose the genesis of a wide variety of normal and abnormal SA nodal and atrial rhythms, (in particular atrial fibrillation).