Numerical simulations of cardiac dynamics. What can we learn from simple and complex models?

Modeling the electrical activity of the heart, and the complex signaling patterns that underlay dangerous arrhythmias such as tachycardia and fibrillation, requires a quantitative model of action potential propagation. At present, there exist detailed ionic models of the Hodgkin-Huxley form that accurately reproduce dynamical features of the action potential at a single cell level. However, such models are very time consuming in computer simulations. The authors show how simplified models can help on the study of cardiac arrhythmias. In particular, how breakup of spiral waves, believed as the dynamics underlying the transition from tachycardia to fibrillation, can occur as function of tissue size and shape. The authors also discuss some of the limitations in these models and some differences in dynamics between simple and complex models.