Swelling of interlamellar GAGs/PGs as an initiation mechanism for aortic dissection: constitutive modeling and numerical simulations

Abstract

Aortic dissection is a life-threatening pathology that mainly affects the medial layer, which consists of multiple lamellar units. Glycosaminoglycans/proteoglycans (GAGs/PGs) can accumulate in the interlamellar space within the media and under certain circumstances swell considerably. Such behavior of GAGs/PGs induces high stresses in the elements connecting the elastic laminae and, in the event of tissue failure, leads to medial delamination and thus to the initiation of aortic dissection. The present study takes up the swelling polymer theory and couples the swelling behavior of GAGs/PGs with the anisotropic response of aortic tissues in order to investigate the initiation mechanism of aortic dissection. The computational simulation uses an advanced weighted constitutive model, which is combined with the global and submodel technique in the finite element software Abaqus. The numerical results show that the proposed method is able to generate failure stresses of the same order of magnitude as the failure stresses indicated in tensile tests. Stress concentrations are observed at the connection between interlamellar struts made of elastic fibers and elastic laminae. Such connections are hotspots at which dissections are expected to initiate. Therefore, this study presents the prediction of the onset of aortic dissection due to the accumulation and swelling of GAGs/PGs and provides a solid foundation for future modeling work.