Abstract
An arterial dissection is a longitudinal tear in the vessel wall, which can create a false lumen for blood flow and may propagate quickly, leading to death. We employ a computational model for a dissection using the extended finite element method with a cohesive traction-separation law for the tear faces. The arterial wall is described by the anisotropic hyperelastic Holzapfel–Gasser–Ogden material model that accounts for collagen fibres and ground matrix, while the evolution of damage is governed by a linear cohesive traction-separation law. We simulate propagation in both peeling and pressure-loading tests. For peeling tests, we consider strips and discs cut from the arterial wall. Propagation is found to occur preferentially along the material axes with the greatest stiffness, which are determined by the fibre orientation. In the case of pressure-driven propagation, we examine a cylindrical model, with an initial tear in the shape of an arc. Long and shallow dissections lead to buckling of the inner wall between the true lumen and the dissection. The various buckling configurations closely match those seen in clinical CT scans. Our results also indicate that a deeper tear is more likely to propagate.
Highlights
Arterial dissection is a cardiovascular disease with a high mortality rate
We develop computational models of arterial dissection to understand the mechanical issues surrounding the development of an existing tear in the arterial wall
We have developed computational models to understand arterial dissection
Summary
Arterial dissection is a cardiovascular disease with a high mortality rate. An arterial dissection begins when a defect arises in the intimal layer of the arterial wall. Ferrara and Pandolfi [4] used the conventional finite element method to model the same problem Both groups used the Holzapfel–Gasser–Ogden (HGO) strainenergy function to describe the mechanical response of the anisotropic arterial wall, but different cohesive tractionseparation laws were used for the evolution of the tear; it is an exponential isotropic function of separation in [3], but a linear function with fibre-dependent directional preference in [4]. The simulations of peeling-driven tear propagation in strips and discs of arterial wall samples are used to study the direction of tear propagation Both plane-strain and three-dimensional models are developed.
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