12. Simulation of Atherosclerotic Plaque Delamination Using the Cohesive Zone Model

Arterial tissue failure leads to a number of potentially life-threatening clinical conditions such as atherosclerotic plaque rupture and aortic dissection, which often occur suddenly and unpredictably in vivo. Atherosclerotic plaque rupture is responsible for roughly 75 % of all newly developed and recurring myocardial infarctions. Mouse models of atherosclerosis are often used in research studies because plaque characteristics can be manipulated experimentally in a reproducible fashion. To simulate atherosclerotic plaque delamination in mouse abdominal aorta, we adopt the Holzapfel model for the bulk material behavior and the cohesive zone model (CZM) for the delamination behavior along the plaque-media interface. In the Holzapfel model, each artery layer is treated as a fiber-reinforced material with the fibers symmetrically disposed with respect to the axial direction of the aorta. In the CZM, delamination is governed by a traction-separation law. A proper set of Holzapfel parameter values and CZM parameter values is determined based on values suggested in the literature and through matching the simulation predictions of the load vs. load-point displacement curve with experimental measurements for one plaque delamination cycle. With the same set of Holzapfel parameter values and CZM parameter values, two more simulation predictions of the load vs. load-point displacement curve were obtained, which match well with experimental measurements, thus validating the CZM approach. Our approach can be readily modified to understand tissue failure processes in human pathologies, e.g. aortic dissection.