Constitutive Modelling of Lamb Aorta
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Vascular inflammation is an established marker of cardiovascular pathogenesis, particularly atherosclerosis, but its role on arterial tissue biomechanics is not well understood. Its impact on the biomechanics of the aorta can yield valuable data for elucidating its role in disease formation, as well as leading to the development of valuable predictive models for surgery and new treatments. Changes in arterial biomechanics can lead to arterial remodelling and dysfunction, and so its quantification can provide insight into the nature of inflammatory processes. To gain further insight into these processes we investigated the biomechanical behaviour of lamb aortas from inflamed and control groups through the development of a constitutive model. The development of reliable constitutive models of the artery is necessary in order to fully understand the mechanical component of cardiovascular disease pathogenesis and vascular remodelling.
We used a foetal sheep model of systemic inflammation induced by prenatal lipopolysaccharide (LPS) treatment (n = 6) to investigate the effects of short-term inflammation on the passive biomechanical response of the aorta. We subjected samples cut from aortas (LPS, n = 6; control, n = 4) to uniaxial tension testing until failure, measuring vessel dimensions and force–displacement curves.
Upon calibration of a first order Ogden model to fit the data, a difference was found in the μ parameter (4.43 × 10−4 ± 3.67 × 10−4 control, 7.77 × 10−4 ± 6.96 × 10−4 LPS-treated) and no difference was noted in the α parameter (12.96 ± 2.145 control, 12.65 ± 3.378 LPS-treated), although neither finding was statistically significant (p > 0.4, p > 0.8, respectively). Our preliminary ex-vivo data suggests that intra-amniotic LPS-induced systemic inflammation does not significantly change the stiffness or strength of the aorta. With further work, we hope our study can help fully elucidate the role of inflammation on aorta biomechanics.
KeywordsStrain Energy Function Constitutive Parameter Stretch Ratio Ogden Model Average Stretch
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