A modified FitzHugh-Nagumo model that allows control of action potential duration and refractory period

To investigate complex electrophysiological behaviour (such as reentrant cardiac arrhythmias) in the setting of the complex anatomy of the heart, the use of a simplified model is computationally more effective. In this study, the Rogers-modified FitzHugh-Nagumo model was further modified to allow control of action potential upstroke velocity, conduction velocity, action potential duration and refractory period. Model parameters were chosen to simulate the action potentials in rabbit sinoatrial node (SAN), atrioventricular node (AVN), atrial muscle and His bundle. The resulting action potential waveforms were a reasonable resembling to experimental data. We have successfully used the models to simulate normal action potential conduction through our rabbit right atrium model. Using a S1-S2 protocol, we were able to simulate an atrial reentrant arrhythmia, reentry occurred around the superior vena cava and the high frequency activity was filtered by the AVN, as observed experimentally.