I numerically model wave propagation in experimental setups of cardiac cells with excitable media, for a project that aims to better understand the onset and termination of reentrant wave propagation. Such wave propagation is thought to be a cause of abnormally rapid heart rhythms called tachycardias.

Students Lucas Campanari and MinJu You create monolayers of embryonic chick heart cells for the experimental setup. They first extract the cells from fertile Leghorn chick eggs and then place obstacles in the cells by adding a compound that stops cells from binding to certain regions of the dish. The obstacles are positioned to create geometries in the cells that support reentrant rhythms, either an annulus geometry or an annulus with an isthmus. A pacemaker naturally occurs in the cells and in several preparations we are able to observe reentrant rhythms.

Often when we observe a reentrant rhythm we do not see the onset or termination of the rhythm. Hence, to try to predict this, I mimic the geometry of the cells and place a pacemaker to resemble the pacemaker in the cells. Furthermore, I can test numerical analogues of treatments that are commonly used in clinical practice such as fast pacing currents or ablations to terminate the rhythm.

I modeled the monolayers with a planar FitzHugh-Nagumo PDE model, where the numerical integration is performed with a centered difference scheme that is implemented in C, and the computation is managed in Python. I use the OpenMP parallel processing package to parallelize the computations, which means that the simulation can be computed fast enough that the user can interact with the simulation in real time.