In a computational model of the rat left ventricle, subject-specific fiber models provided little improvement in predicting deformation metrics compared to global rule-based models.
Does a subject-specific fibre model or material orthotropy improve the predictive power of a computational model of rat left ventricular contraction?
In a computational model of rat left ventricular electromechanics, material orthotropy improves prediction of cardiac deformation more than subject-specific fibre models, highlighting the need for further investigation into sheet dynamics.
Tissue microstructure, in particular the alignment of myocytes (fibre direction) and their lateral organisation into sheets, is fundamental to cardiac function. We studied the effect of microstructure on contraction in a computational model of rat left ventricular electromechanics. Different fibre models, globally rule-based or locally optimised to DT-MRI data, were compared, in order to understand whether a subject-specific fibre model would enhance the predictive power of our model with respect to the global ones. We also studied the impact of sheets on ventricular deformation by comparing: (a) a transversely isotropic versus an orthotropic material law and (b) a linear model with a bimodal model of sheet transmural variation. We estimated ejection fraction, wall thickening and base-to-apex shortening and compared them with measures from cine-MRI. We also evaluated Lagrangian strains as local metrics of cardiac deformation. Our results show that the subject-specific fibre model provides little improvement in the metric predictions with respect to global fibre models while material orthotropy allows closer agreement with measures than transverse isotropy. Nonetheless, the impact of sheets in our model is smaller than that of fibres. We conclude that further investigation of the modelling of sheet dynamics is necessary to fully understand the impact of tissue structure on cardiac deformation.
Carapella et al. (Wed,) conducted a other in Healthy rat left ventricle (computational model) (n=6). Subject-specific fiber model and orthotropic material law vs. Global rule-based fiber models and transversely isotropic material law was evaluated on Ejection fraction, wall thickening, and base-to-apex shortening. In a computational model of the rat left ventricle, subject-specific fiber models provided little improvement in predicting deformation metrics compared to global rule-based models.