Structure-based constitutive model can accurately predict planar biaxial properties of aortic wall tissue

Polzer, Stanislav; Gasser, Thomas C.; Novák, Kamil; Man, Vojtěch; Tichý, Michal; Skácel, Pavel; Burša, Jiří

doi:10.1016/j.actbio.2014.11.043

Cited by 69 publications

(57 citation statements)

References 64 publications

(132 reference statements)

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“…This study shows the strong variation and dependence of the distribution of collagen fiber orientations on the specific tissue location and especially on the wall layer. Like other studies (Canham et al, 1989;Finlay et al, 1995;Polzer et al, 2015;Rezakhaniha et al, 2012), the present data also shows that the collagen mean orientation points is the circumferential direction in a normal media aorta, and on contrast to Schriefl et al (2012) that found two clear fiber families for the intima, media and adventitia for both thoracic and abdominal human aortas. This effect is probably because of the data in our study is from porcine aortas and the dispersion in collagen fiber orientation was significantly lower than the aged human aortic media.…”

Section: Discussioncontrasting

confidence: 61%

Layer-specific residual deformations and uniaxial and biaxial mechanical properties of thoracic porcine aorta

Peña

Martı́nez

Peña

2015

Journal of the Mechanical Behavior of Biomedical Materials

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Section: Discussioncontrasting

confidence: 61%

Layer-specific residual deformations and uniaxial and biaxial mechanical properties of thoracic porcine aorta

Peña

Martı́nez

Peña

2015

Journal of the Mechanical Behavior of Biomedical Materials

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“…Our data was based on analyzing a rather small area of the histological slices, and the dispersion is expected to increase when increasing the analyzing area, which, however, would require automatic methods, see for example [26]. We could not observe different families of collagen fibers with respect to the azimuthal angles, as it has been postulated previously in the literature for other vessels [13].…”

Section: Family Of Collagen Fibers With Positive Elevationsupporting

confidence: 48%

“…Similarly, we used only three histological sections across the wall to identify the collagen organization, which would have overlooked potential gradual changes, i.e. as recently reported for the porcine aorta [26], for example. Consequently, a refined analysis should explore the radial inhomogeneity of both, collagen histology and mechanical wall properties, respectively.…”

Section: Family Of Collagen Fibers With Positive Elevationmentioning

confidence: 99%

“…Despite the fact that considerable work has been dedicated to develop and numerically implement structural SEFs, only very few studies consistently validated structural SEFs, i.e. by treating histological and mechanical input information strictly separately [12,15,26,37]. In contrast, most studies estimated both histological and mechanical model parameters from mechanical experimental data, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural quantification of collagen fiber orientations and its integration in constitutive modeling of the porcine carotid artery

et al. 2016

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Background Mechanical characteristics of vascular tissue may play a role in different arterial pathologies, which, amongst others, requires robust constitutive descriptions to capture the vessel wall’s anisotropic and non-linear properties.Specifically, the complex 3D network of collagen and its interaction with other structural elements has a dominating effect of arterial properties at higher stress levels.The aim of this study is to collect quantitative collagen organization as well as mechanical properties to facilitate structural constitutive models for the porcine carotid artery.This helps the understanding of the mechanics of swine carotid arteries, being a standard in clinical hypothesis testing, in endovascular preclinical trials for example. Method Porcine common carotid arteries (n = 10) were harvested and used to (i) characterize the collagen fiber organization with polarized light microscopy, and (ii) the biaxial mechanical properties by inflation testing.The collagen organization was quantified by the Bingham orientation density function (ODF), which in turn was integrated in a structural constitutive model of the vessel wall.A one-layered and thick-walled model was used to estimate mechanical constitutive parameters by least-square fitting the recorded in vitro inflation test results.Finally, uniaxial data published elsewhere were used to validate the mean collagen organization described by the Bingham ODF. Results Thick collagen fibers, i.e.the most mechanically relevant structure, in the common carotid artery are dispersed around the circumferential direction.In addition, almost all samples showed two distinct families of collagen fibers at different elevation, but not azimuthal, angles.Collagen fiber organization could be accurately represented by the Bingham ODF (¿1,2,3=[13.5,0.0,25.2] and ¿1,2,3=[14.7,0.0,26.6]; average error of about 5%), and their integration into a structural constitutive model captured the inflation characteristics of individual carotid artery samples.Specifically, only four mechanical parameters were required to reasonably (average error from 14% to 38%) cover the experimental data over a wide range of axial and circumferential stretches.However, it was critical to account for fibrilar links between thick collagen fibers.Finally, the mean Bingham ODF provide also good approximation to uniaxial experimental data. Conclusions The applied structural constitutive model, based on individually measured collagen orientation densities, was able to capture the biaxial properties of the common carotid artery. Since the model required coupling amongst thick collagen fibers, the collagen fiber orientations measured from polarized light microscopy, alone, seem to be insufficient structural information. Alternatively, a larger dispersion of collagen fiber orientations, that is likely to arise from analyzing larger wall sections, could have had a similar effect, i.e. could have avoided coupling amongst thick collagen fibers.Peer ReviewedPostprint (author's final draft

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“…To further increase the understanding and to improve rupture risk prediction it is necessary to study effects of localized wall changes (shown, for example, for cerebral aneurysms in [38]) by combining the microstructure with patient-specific mechanical data and systematically compare these changes with healthy abdominal aortic tissues. Such a knowledge can then be used to improve numerical models incorporating structurebased nonlinear material models, as was recently performed in [39] where the biaxial response of porcine aortic tissues was combined with the related microstructure identified using histological slices.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and mechanics of healthy and aneurysmatic abdominal aortas: experimental analysis and modelling

Niestrawska

Viertler

Regitnig

et al. 2016

J. R. Soc. Interface.

144

178

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Soft biological tissues such as aortic walls can be viewed as fibrous composites assembled by a ground matrix and embedded families of collagen fibres. Changes in the structural components of aortic walls such as the ground matrix and the embedded families of collagen fibres have been shown to play a significant role in the pathogenesis of aortic degeneration. Hence, there is a need to develop a deeper understanding of the microstructure and the related mechanics of aortic walls. In this study, tissue samples from 17 human abdominal aortas (AA) and from 11 abdominal aortic aneurysms (AAA) are systematically analysed and compared with respect to their structural and mechanical differences. The collagen microstructure is examined by analysing data from second-harmonic generation imaging after optical clearing. Samples from the intact AA wall, their individual layers and the AAA wall are mechanically investigated using biaxial stretching tests. A bivariate von Mises distribution was used to represent the continuous fibre dispersion throughout the entire thickness, and to provide two independent dispersion parameters to be used in a recently proposed material model. Remarkable differences were found between healthy and diseased tissues. The out-of-plane dispersion was significantly higher in AAA when compared with AA tissues, and with the exception of one AAA sample, the characteristic wall structure, as visible in healthy AAs with three distinct layers, could not be identified in AAA samples. The collagen fibres in the abluminal layer of AAAs lost their waviness and exhibited rather straight and thick struts of collagen. A novel set of three structural and three material parameters is provided. With the structural parameters fixed, the material model was fitted to the mechanical experimental data, giving a very satisfying fit although there are only three material parameters involved. The results highlight the need to incorporate the structural differences into finite-element simulations as otherwise simulations of AAA tissues might not be good predictors for the actual in vivo stress state.

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Structure-based constitutive model can accurately predict planar biaxial properties of aortic wall tissue

Cited by 69 publications

References 64 publications

Layer-specific residual deformations and uniaxial and biaxial mechanical properties of thoracic porcine aorta

Layer-specific residual deformations and uniaxial and biaxial mechanical properties of thoracic porcine aorta

Microstructural quantification of collagen fiber orientations and its integration in constitutive modeling of the porcine carotid artery

Microstructure and mechanics of healthy and aneurysmatic abdominal aortas: experimental analysis and modelling

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