Microstructure-based constitutive model of coronary artery with active smooth muscle contraction

H Chen,G S Kassab

doi:10.1038/s41598-017-08748-7

Abstract

Currently, there is no full three-dimensional (3D) microstructural mechanical model of coronary artery based on measured microstructure including elastin, collagen and smooth muscle cells. Many structural models employ mean values of vessel microstructure, rather than continuous distributions of microstructure, to predict the mechanical properties of blood vessels. Although some models show good agreements on macroscopic vessel responses, they result in a lower elastin stiffness and earlier collagen recruitment. Hence, a full microstructural constitutive model is required for better understanding vascular biomechanics in health and disease. Here, a 3D microstructural model that accounts for all constituent microstructure is proposed to predict macroscopic and microscopic responses of coronary arteries. Coronary artery microstructural parameters were determined based on previous statistical measurements while mechanical testing of arteries (n = 5) were performed in this study to validate the computational predictions. The proposed model not only provides predictions of active and passive stress distributions of vessel wall, but also enables reliable estimations of material parameters of individual fibers and cells and thus predicts microstructural stresses. The validated microstructural model of coronary artery sheds light on vascular biomechanics and can be extend to diseased vessels for better understanding of initiation, progression and clinical treatment of vascular disease.

Highlights

An in-depth understanding of mechanical properties of coronary arteries is essential for elucidating the mechanism of initiation and progression of vascular disease[1,2,3]
Geometrical distribution parameters were refined by imposing restrictions to ensure fibers/cells follow statistical distributions previously measured, which leads to even better prediction of passive and active responses and provides a reliable estimate of material parameters of individual fibers and cells
The measurements of total and passive arterial responses are compared with model predictions under two different axial stretch ratios λz = 1.3 and 1.5, respectively

Summary

Introduction

An in-depth understanding of mechanical properties of coronary arteries is essential for elucidating the mechanism of initiation and progression of vascular disease[1,2,3]. Zhou et al incorporated a four-fiber passive constitutive model with a biaxial model of SMCs contraction to investigate biaxial active stresses for the porcine primary renal artery[19], while Takamizawa developed a triaxial constitutive law to describe the multi-axial active mechanical properties of constricted carotid arteries[20]. These models, were 2D models as they assumed uniform stress distribution through the wall thickness and they were not microstructure-based models that exclude orientation distributions of SMCs in the media. The estimated material parameters were compared with those of a mean-value approach that eliminates continuous distribution of microstructure to show that the full measured fiber distributions are necessary to obtain realistic material parameters

Methods

Results

Conclusion