A micromechanical perspective on ascending aortic dissection: A multiscale computational framework

Acute ascending aortic dissection (AAD) is a life-threatening cardiovascular emergency characterized by the delamination of the aortic wall and the subsequent formation of a false lumen. A hallmark histopathological feature of AAD is the localized accumulation of glycosaminoglycans (GAGs) and proteoglycans within the middle layer, a phenomenon known as translamellar mucoid extracellular matrix accumulation (T-MEMA). It is hypothesized that T-MEMA induces local swelling via Donnan osmotic pressure, generating highly localized radial stresses that predispose the tissue to delamination. In this study, we developed a multiscale computational framework to investigate the mechanistic implications of T-MEMA in the ascending aorta. By integrating finite element simulations with a Donnan-based swelling formulation, we quantified how GAG-induced swelling alters macro-scale stress distributions and exacerbates micro-scale stresses within interlamellar components, specifically the radial elastin struts. Our analysis establishes a quantitative relationship between histopathological observations and the biomechanical triggers of AAD, demonstrating that the transmural location of T-MEMA significantly determines the propensity for wall delamination.