Modelling of fibre dispersion and its effects on cardiac mechanics from diastole to systole

Guan, D., Zhuan, X., Holmes, W. , Luo, X. and Gao, H. (2021) Modelling of fibre dispersion and its effects on cardiac mechanics from diastole to systole. Journal of Engineering Mathematics, 128, 1. (doi: 10.1007/s10665-021-10102-w)

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Detailed fibre architecture plays a crucial role in myocardial mechanics both passively and actively. Strong interest has been attracted over decades in mathematical modelling of fibrous tissue (arterial wall, myocardium, etc.) by taking into account realistic fibre structures, i.e. from perfectly aligned one family of fibres, to two families of fibres, and to dispersed fibres described by probability distribution functions. It is widely accepted that the fibres, i.e. collage, cannot bear the load when compressed, thus it is necessary to exclude compressed fibres when computing the stress in fibrous tissue. In this study, we have focused on mathematical modelling of fibre dispersion in myocardial mechanics, and studied how different fibre dispersions affect cardiac pump function. The fibre dispersion in myocardium is characterized by a non-rotationally symmetric distribution using a π-periodic Von Mises distribution based on recent experimental studies. In order to exclude compressed fibres for passive response, we adopted the discrete fibre dispersion model for approximating a continuous fibre distribution with finite fibre bundles, and then the general structural tensor was employed for describing dispersed active tension. We first studied the numerical accuracy of the integration of fibre contributions using the discrete fibre dispersion approach, then compared different mechanical responses in a uniaxially stretched myocardial sample with varied fibre dispersions. We finally studied the cardiac pump functions from diastole to systole in two heart models, a rabbit bi-ventricle model and a human left ventricle model. Our results show that the discrete fibre model is preferred for excluding compressed fibres because of its high computational efficiency. Both the diastolic filling and the systolic contraction will be affected by dispersed fibres depending on the in-plane and out-of-plane dispersion degrees, especially in systolic contraction. The in-plane dispersion seems affecting myocardial mechanics more than the out-of-plane dispersion. Despite different effects in the rabbit and human models caused by the fibre dispersion, large differences in pump function exist when fibres are highly dispersed at in-plane and out-of-plane. Our results highlight the necessity of using dispersed fibre models when modelling myocardial mechanics, especially when fibres are largely dispersed under pathological conditions, such as fibrosis.

Item Type:Articles
Additional Information:We are grateful for the funding provided by the UK EPSRC (EP/N014642/1, EP/S030875, EP/S020950/1, EP/S014284/1). H.G. further acknowledges the EPSRC ECR Capital Award (308011) from UofG for supporting the DT-MRI acquisition. DG also acknowledges funding from the Chinese Scholarship Council and the fee waiver from the University of Glasgow.
Glasgow Author(s) Enlighten ID:Luo, Professor Xiaoyu and Guan, Mr Debao and Gao, Dr Hao and Zhuan, Mr Xin and Holmes, Dr William
Authors: Guan, D., Zhuan, X., Holmes, W., Luo, X., and Gao, H.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Journal of Engineering Mathematics
ISSN (Online):1573-2703
Published Online:20 April 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in Journal of Engineering Mathematics 128:1
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
172141EPSRC Centre for Multiscale soft tissue mechanics with application to heart & cancerRaymond OgdenEngineering and Physical Sciences Research Council (EPSRC)EP/N014642/1M&S - Mathematics
303232EPSRC Centre for Multiscale soft tissue mechanics with MIT and POLIMI (SofTMech-MP)Xiaoyu LuoEngineering and Physical Sciences Research Council (EPSRC)EP/S030875/1M&S - Mathematics
303231A whole-heart model of multiscale soft tissue mechanics and fluid structureinteraction for clinical applications (Whole-Heart-FSI)Xiaoyu LuoEngineering and Physical Sciences Research Council (EPSRC)EP/S020950/1M&S - Mathematics
303798Growth and Remodelling in Neoanatal Porcine Heart-- Pushing Mathematics through ExperimentsXiaoyu LuoEngineering and Physical Sciences Research Council (EPSRC)EP/S014284/1M&S - Mathematics