engleski

Influence of fiber dispersion on growth and remodeling of abdominal aortic aneurysms

Human aortas can be considered as layered fibrous composites with collagen fibers and smooth muscle cells embedded into a ground matrix. Collagen fibers are dispersed within the aortic wall, however, they are typically grouped into two families with mean fiber direction and dispersion around it. Studies have shown that fiber dispersion effect the mechanical response of the aortic wall and it is different in each aortic layer. Furthermore, in diseased aortas microstructure and fiber dispersion significantly alter, effecting in that way mechanical properties of the aortic wall. To the authors’ knowledge, none of the numerical studies describing the adaptation of healthy and diseased aortas in response to different stimuli takes fiber dispersions into account. In this study, a non- symmetric fiber dispersion model is implemented into a constrained mixture growth and remodeling model using a generalized structure tensor approach. A finite element software was then used to analyze the influence of various fiber dispersion on abdominal aortic aneurysm growth and on stress distribution inside the aortic wall. Results obtained with a three-layered axisymmetric abdominal aortic aneurysm model have shown that collagen fiber dispersion has a significant influence on aneurysm growth. For example, an increase of fiber dispersion in intima and adventitia leads to a slower growth rate, while the increase of dispersion in adventitia results in a faster growth rate. Furthermore, a simultaneous increase of fiber dispersion in all layers tends to level the circumferential and axial stresses throughout the wall thickness, whereas aligned fibers increase the circumferential stress in the intima and axial stress in the adventitia. Considering the results, we suggest that modeling of the fiber dispersion should not be neglected in future G&R studies of abdominal aortic aneurysms.

aneurysm ; fluid-solid growth

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