  We explore an embryonic heart model that couples electrophysiology and
muscle-force generation to flow induced using a $2D$ fluid-structure
interaction framework based on the immersed boundary method. The propagation of
action potentials are coupled to muscular contraction and hence the overall
pumping dynamics. In comparison to previous models, the electro-dynamical model
does not use prescribed motion to initiate the pumping motion, but rather the
pumping dynamics are fully coupled to an underlying electrophysiology model,
governed by the FitzHugh-Nagumo equations. Perturbing the diffusion parameter
in the FitzHugh-Nagumo model leads to a bifurcation in dynamics of action
potential propagation. This bifurcation is able to capture a spectrum of
different pumping regimes, with dynamic suction pumping and peristaltic-like
pumping at the extremes. We find that more bulk flow is produced within the
realm of peristaltic-like pumping.
