Insights Into Regional Adaptations in the Growing Pulmonary Artery Using a Meso-Scale Structural Model: Effects of Ascending Aorta Impingement

Fata, Bahar; Zhang, Will; Amini, Rouzbeh; Sacks, Michael S.

doi:10.1115/1.4026457

Cited by 36 publications

(59 citation statements)

References 44 publications

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“…To statistically compare the degree of anisotropy between the normo- and hypertensive states, the differences between maximum values of S LL and S CC were computed from the interpolated equi-biaxial response, in which E LL = E CC (19,46). A larger difference would indicate a higher degree of anisotropy, i.e., the stress-strain responses along the longitudinal and circumferential directions would follow distinctly different paths.…”

Section: Methodsmentioning

confidence: 99%

Structural and Mechanical Adaptations of Right Ventricle Free Wall Myocardium to Pressure Overload

et al. 2014

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Right ventricular (RV) failure in response to pulmonary hypertension (PH) is a severe disease that remains poorly understood. PH-induced pressure overload leads to changes in the RV free wall (RVFW) that eventually results in RV failure. While the development of computational models can benefit our understanding of the onset and progression of PH-induced pressure overload, detailed knowledge of the underlying structural and biomechanical events remains limited. The goal of the present study was to elucidate the structural and biomechanical adaptations of RV myocardium subjected to sustained pressure overload in a rat model. Hemodynamically confirmed severe chronic RV pressure overload was induced in Sprague-Dawley rats via pulmonary artery banding. Extensive tissue-level biaxial mechanical and histomorphological analyses were conducted to assess the remodeling response in the RV free wall. Simultaneous myofiber hypertrophy and longitudinal re-orientation of myo- and collagen fibers was observed, with both fiber types becoming more highly aligned. Transmural myo- and collagen fiber orientations were co-aligned in both the normal and diseased state. The overall tissue stiffness increased, with larger increases in longitudinal versus circumferential stiffness. Interestingly, estimated myofiber stiffness increased while the collagen fiber stiffness remained unchanged. The latter was attributed to longitudinal fiber re-orientation, which increased the degree of anisotropy. Increased mechanical coupling between the two axes was attributed to the increased fiber alignment. The increased myofiber stiffness was consistent with clinical results showing titin-associated increased sarcomeric stiffening observed in PH patients. These results further our understanding of the underlying adaptive and maladaptive remodeling mechanisms and may lead to improved techniques for prognosis, diagnosis, and treatment for PH.

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Section: Methodsmentioning

confidence: 99%

Structural and Mechanical Adaptations of Right Ventricle Free Wall Myocardium to Pressure Overload

et al. 2014

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“…(1) From the native tissue mechanical data, predict the collagen phase parameters ðh c , m G , sG, m 0 , s 0 Þ using standard procedures [33,63]. We found that this basic sequence ensured a robust parameter is obtained, because the entire model is never fitted at once.…”

Section: Parameter Estimation Proceduresmentioning

confidence: 99%

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

2016

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Exogenous cross-linking of soft collagenous tissues is a common method for biomaterial development and medical therapies. To enable improved applications through computational methods, physically realistic constitutive models are required. Yet, despite decades of research, development and clinical use, no such model exists. In this study, we develop the first rigorous full structural model (i.e. explicitly incorporating various features of the collagen fibre architecture) for exogenously cross-linked soft tissues. This was made possible, in-part, with the use of native to cross-linked matched experimental datasets and an extension to the collagenous structural constitutive model so that the uncross-linked collagen fibre responses could be mapped to the cross-linked configuration. This allowed us to separate the effects of cross-linking from kinematic changes induced in the cross-linking process, which in turn allowed the non-fibrous tissue matrix component and the interaction effects to be identified. It was determined that the matrix could be modelled as an isotropic material using a modified Yeoh model. The most novel findings of this study were that: (i) the effective collagen fibre modulus was unaffected by cross-linking and (ii) fibre-ensemble interactions played a large role in stress development, often dominating the total tissue response (depending on the stress component and loading path considered). An important utility of the present model is its ability to separate the effects of exogenous cross-linking on the fibres from changes due to the matrix. Applications of this approach include the utilization in the design of novel chemical treatments to produce specific mechanical responses and the study of fatigue damage in bioprosthetic heart valve biomaterials.

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“…The cell-network system was stretched by different amounts (5,10,15,20,25,30,35,40,45,50, 55 and 60% strain) before remodelling. The system was stretched uniaxially and incompressibility was enforced.…”

Section: System Deformationmentioning

confidence: 99%

“…Significant strides have been made through the use of theoretical models that treat the cells and ECM as a continuum (e.g. [18][19][20][21][22]). In particular, many models invoke the concept of tensional homeostasis, in which cells grow and/or modify the ECM to achieve a target stress.…”

Section: Introductionmentioning

confidence: 99%

Cell–matrix interaction during strain-dependent remodelling of simulated collagen networks

et al. 2016

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The importance of tissue remodelling is widely accepted, but the mechanism by which the remodelling process occurs remains poorly understood. At the tissue scale, the concept of tensional homeostasis, in which there exists a target stress for a cell and remodelling functions to move the cell stress towards that target, is an important foundation for much theoretical work. We present here a theoretical model of a cell in parallel with a network to study what factors of the remodelling process help the cell move towards mechanical stability. The cell-network system was deformed and kept at constant stress. Remodelling was modelled by simulating strain-dependent degradation of collagen fibres and four different cases of collagen addition. The model did not lead to complete tensional homeostasis in the range of conditions studied, but it showed how different expressions for deposition and removal of collagen in a fibre network can interact to modulate the cell's ability to shield itself from an imposed stress by remodelling the surroundings. This study also showed how delicate the balance between deposition and removal rates is and how sensitive the remodelling process is to small changes in the remodelling rules.

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Insights Into Regional Adaptations in the Growing Pulmonary Artery Using a Meso-Scale Structural Model: Effects of Ascending Aorta Impingement

Cited by 36 publications

References 44 publications

Structural and Mechanical Adaptations of Right Ventricle Free Wall Myocardium to Pressure Overload

Structural and Mechanical Adaptations of Right Ventricle Free Wall Myocardium to Pressure Overload

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

Cell–matrix interaction during strain-dependent remodelling of simulated collagen networks

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