High resolution cardiac electrophysiology numerical models – HR-CEM

Cardiovascular diseases are responsible for 700 000 death each year in Europe, half of which are directly related to cardiac ventricular tachyarrythmias. Together with 6 million individuals suffering from atrial fibrillation, it has become a major burden for the people and the health care system in Europe.
Cardiac modelling has evolved incredibly over more than 50 years, providing the most highly detailed mathematical description of any organ system in the body. Many fundamental insights have been gained from in-silico experiments. Cardiac electrical activity is determined by the molecular activity through the cell membrane that is organised at the tissue, organ, and body levels. Cardiac arrhythmias are complex disruptions of this organisation. Numerical models and fast dedicated solvers already exist that allow in-silico exploration of the mechanisms underlying these pathologies at the cost of large-scale simulations. The models are degenerate reaction-diffusion systems of equations coupled to stiff systems of differential equations, and the solvers are currently based on parallel first order robust though inaccurate techniques.
However, current numerical models lack many important features. Due to their conceptual formalism, theydo not account properly for the heterogeneous microstructure of the tissue, nor for the multidimensional coupling between cardiac components. In addition, we have a very incomplete understanding of the numerical errors induced by the algorithms. Finally, validation of these numerical models is a very challenging, and open, research question.
Numerical modelling plays an increasing role in the development of knowledge in cardiac electrophysiology but these issues limit the reliability of the models, and our capacity to explore in depth complex pathological mechanisms.
The LIRYC institute provides an environment where modellers can efficiently interact with clinical and experimental researchers. Several members from LIRYC already associated with the Carmen team of applied mathematicians, and Pr Bourgault from the University of Ottawa, constitute the multidisciplinary group that will challenge the modelling, numerical and validation issues detailed above. All researchers are specialists in cardiac electrophysiology from the modelling, experimental or medical point of views.
Based on this environment and new developments in structural and functional imaging of the heart available at LIRYC, we plan to reconsider the concepts behind the models in order to improve the accuracy and efficiency of simulations. Cardiac simulation software and high-resolution numerical models will be derived from experimental data from animal models. Validation will be performed by comparing of simulation output with experimentally recorded functional data. The validated numerical models will be made available to the community of researchers that take advantage of in-silico cardiac simulation and, hopefully, become references. In particular we shall provide the first exhaustive model of an animal heart including the four chambers coupled through the special conduction network, with highly detailed microstructure of both the atria and the ventricles.
Such a model embedded in high-performance computational software will provide stronger medical foundations for in-silico experimentation, and elucidate mechanisms of cardiac arrhythmias.