The role of radial elastic properties in the development of aortic dissections

Abstract

Although the aorta normally functions under radial compressive stresses associated with lumen blood pressure, these results show that the aorta tears radially at a much lower value of stress than would have been predicted from previous studies that have reported longitudinal and circumferential Young's modulus. This could explain why dissections propagate readily once the initial tear occurs.

Failure of the Porcine Ascending Aorta: Multidirectional Experiments and a Unifying Microstructural Model

“…Elastin fibers were generated such that orientation was approximately isotropic within the plane. The radial properties of the aorta are less well established [52,53] but are extremely important because failure of the interlamellar connections dictates delamination and thus aortic dissection. Within the model network, the interlamellar connections were designed to encompass the combined effect of all structural components (smooth muscle cells, fine collagen fibers, and fine elastin fibers) contributing to radial strength.…”

“…While clearly the interlamellar connections encompass some collagen, and the elastic lamina contains large amounts of elastin, we utilized this 1:1 ratio. Initial estimates of the fiber parameters (fiber stiffness, nonlinearity, and failure stretch) for collagen and elastin were based on our previous works [21,43], and those for the interlamellar connections were specified based on MacLean's experimental stress-strain behavior of the upper thoracic aorta subjected to radial failure [53]. Properties were subsequently adjusted such that a single set of model parameters matched results from the suite of experiments performed herein; the final parameter values are given in Table 2.…”

Loosely Coupled Simulation for Aortic Arch Model under Steady and Pulsatile Flow

“…Wall stress is an important factor in aortic dissection, which has been recently addressed by several authors [3,4,26,27,28]. The variations of circumferential, longitudinal, and radial stress along arch at steady flow condition and at systolic acceleration (t 1 ), peak entrance flow (t 2 ) of pulsatile flow have a similar pattern.…”

“…Under normal conditions, radial stresses are compressive. MacLean et al [4] showed that the aorta tore radially at a much lower value of radial tensile stress and mentioned that once a false lumen is formed by a dissection, radial tensile forces must exist in the aortic wall. In the present study, radial tensile stress exists due to the structure of arch and deformations of the wall.…”

“…Thubrikar et al [3] proposed that longitudinal stress could be responsible for the tear in the aortic dissection. MacLean et al [4] showed the role of radial tensile stress in aortic dissection. The simulation of the fluid-structure interaction (FSI) in large arterial vessel can provide the insight of a risk predictor for aortic wall tear, aortic dissection, and so on.…”