DAD characterization in electromechanical cardiac models (Q379450)

The authors study the FitzHugh-Nagumo model and consider ``delayed after depolarizations'' (DADs), the phenomenon in which the voltage variable increases through a (largely-arbitrary) threshold more than once, before approaching a fixed point. They first consider the ODE version and numerically determine the dependence of this phenomenon on several parameters of the model. They then consider the PDE version in one spatial dimension, where the voltage variable undergoes diffusion. By moving to a travelling coordinate frame and studying the resulting two ODEs, they obtain similar results, determining when a DAD may both occur and propagate. They lastly consider an electro-mechanical generalization of the FitzHugh-Nagumo model which, after several simplifications, reduces to another pair of ODEs that are analyzed as above.