RESUMO
Heart failure is a major and costly problem in public health, which, in certain cases, may lead to death. The failing heart undergo a series of electrical and structural changes that provide the underlying basis for disturbances like arrhythmias. Computer models of coupled electrical and mechanical activities of the heart can be used to advance our understanding of the complex feedback mechanisms involved. In this context, there is a lack of studies that consider heart failure remodeling using strongly coupled electromechanics. We present a strongly coupled electromechanical model to study the effects of deformation on a human left ventricle wedge considering normal and hypertrophic heart failure conditions. We demonstrate through a series of simulations that when a strongly coupled electromechanical model is used, deformation results in the thickening of the ventricular wall that in turn increases transmural dispersion of repolarization. These effects were analyzed in both normal and failing heart conditions. We also present transmural electrograms obtained from these simulations. Our results suggest that the waveform of electrograms, particularly the T-wave, is influenced by cardiac contraction on both normal and pathological conditions.
Assuntos
Acoplamento Excitação-Contração , Sistema de Condução Cardíaco/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Modelos Cardiovasculares , Contração Miocárdica , Disfunção Ventricular Esquerda/fisiopatologia , Animais , Simulação por Computador , Módulo de Elasticidade , Insuficiência Cardíaca/complicações , Humanos , Mecanotransdução Celular , Estresse Mecânico , Disfunção Ventricular Esquerda/complicaçõesRESUMO
Recently, B. Roth and M. Woods [7] suggested a reexamination of MCG interpretation through currents transversal to the wave propagation direction. They also gave a formula J'(theta) for the dependence of the current intensity on the angle theta between straight fibers and the plane wave front. Here we study more general situations, including current injection at multiple points and curved fibers. We conclude that transversal currents are always present locally, in spite of electric pattern complexity and fiber curvature. Moreover, the J'(theta) relation holds locally. Nevertheless, computations indicate that macroscopically the far magnetic field may be similar to the one generated by a current dipole parallel to the wave propagation direction.