Modelagem da atividade eletromecânica do coração e os efeitos da deformação na repolarizacão

Abstract

Computational modelling of the heart has been focus of a growing interest from the medical and scientific community due to its importance for the com-prehension of several phenomena associated with the physiological behaviour of the heart under normal and pathological conditions, for the study of new treat-ment therapies and the development of new drugs. The phenomena of interest presents a great complexity due to its multiscale and multiphysics characteristics and requires the interaction of different mathematical models. The objective of the present work is the develop a computer model to des-cribe the coupled electrical and mechanical activities of the heart. This model is then used to study and understand the effects of cardiac tissue deformation on electrophysiological parameters. The mathematical model developed here couples the effects of the electrical propagation on cardiac tissue to the mechanical problem that describes the moviment and deformation of the tissue. To describe the dynamics of electrophysiology and the generation of active force in cardiac myocytes of the left ventricle, ordinary differential equations are coupled to a system of partial differential equations that models the electrical activity at tissue level. The active force generated by cardiac myocytes is then used as input to the mechanical model to describe the deformation of the tissue. The mechanical model considers the cardiac tissue as a nonlinear hyperelastic, orthotropic and incompressible material. The models are coupled such that the deformation obtained from the mechanical problem affects the electrophysiological model. The numerical solution of the complex multiscale and multiphysics model is performed using the finite element method and other ro-bust and efficient numerical methods. We also incorporate some parallel computing techniques for accelerating the solution in some parts of the problem. Several numerical simulations were carried out to characterize the electrical and mechanical activities of the cardiac tissue. In this context we present a sim-plified model of the human left ventricle, which considers the presence of different cardiac myocytes within the ventricular wall, to study the effects of deformation on some important electrophysiological parameters, such as repolarization time and action potential duration. From the results of the simulations, we computed electrograms to assess the effects of deformation on them when compared to simulations without deformation. The results of this work show that deformation of cardiac tissue considerably affects repolarization and action potential duration in a wedge of the human left ventricle. We also show that the deformation causes an increase in the amplitude of the T-wave measured in the simulated electrograms.