Planar biaxial characterization of diseased human coronary and carotid arteries for computational modeling

Abstract

Computational models have the potential to provide precise estimates of stresses and strains associated with sites of coronary plaque rupture. However, lack of adequate mathematical description of diseased human vessel wall mechanical properties is hindering computational accuracy. The goal of this study is to characterize the behavior of diseased human coronary and carotid arteries using planar biaxial testing. Diseased coronary specimens exhibit relatively high stiffness (50–210 kPa) and low extensibility (1–10%) at maximum equibiaxial stress (250 kPa) compared to human carotid specimens and values commonly reported for porcine coronary arteries. A thick neointimal layer observed histologically appears to be associated with heightened stiffness and the direction of anisotropy of the specimens. Fung, Choi-Vito and modified Mooney-Rivlin constitutive equations fit the multiaxial data from multiple stress protocols well, and parameters from representative coronary specimens were utilized in a finite element model with fluid-solid interactions. Computed locations of maximal stress and strain are substantially altered, and magnitudes of maximum principal stress (48–65 kPa) and strain (6.5–8%) in the vessel wall are lower than previously predicted using parameters from uniaxial tests. Taken together, the results demonstrate the importance of utilizing disease-matched multiaxial constitutive relationships within patient-specific computational models to accurately predict stress and strain within diseased coronary arteries.

Inflation and Bi-Axial Tensile Testing of Healthy Porcine Carotid Arteries

“…For vascular tissue, bi-axial tensile testing is preferred over uni-axial testing, because of the tissue's anisotropy and the loading of the tissue in all directions in vivo. Several studies have reported on uni-and bi-axial tensile testing of carotid arteries, either with or without atherosclerotic plaque (Choserot et al 2005;Kural et al 2012;Lawlor et al 2011;Maher et al 2009). Similar measurements were reported for coronary arteries (Lally et al 2004) and healthy or aneurysmal aortic tissue (Duprey et al 2010;Holzapfel and Ogden 2006;Nicosia et al 2002;Okamoto et al 2002).…”

A parametric model for analysing atherosclerotic arteries: On the FSI coupling

“…While several FSI simulations have been performed in 2D models [22,23], 3D models have also been utilized to predict wall shear stress and wall stress patterns in healthy subjects [24]. Tang and coworkers [25][26][27][28][29][30][31] extensively work on FSI approach of atheromatous plaque using patient specific-based models and performing statistical analysis for carotid and coronary arteries. Li et al [32] constructed an idealized 3D atheroma plaque model with varying stenosis degree of 30%, 50% and 70%, to study the wall motion in plaque throat.…”

Effects of longitudinal asymmetric distribution of a lipid core on plaque wall stress

“…The parameters in the strain energy density function, C1, C2, D1, D2, K 1 , and K2, were chosen to match the mechanical properties of the plaque wall obtained from experimental measurements. Data from planar biaxial tests of coronary arteries were used (Kural et al, 2012) to fit the modified Mooney-Rivlin model, and the parameters in the strain energy density function were C1=-1312.9 kPa, C2=114.7 kPa, D1=629.7 kPa, D2=2.0, K 1 =35.9 kPa, K 2 =23.5. The lipid core was assumed to be incompressible and isotropic with C1=0.5 kPa, D1=0.5 kPa and D2=0.5, and C2 and K 1 are zeroes.…”