A numerical framework for studying the biomechanical behavior of abdominal aortic aneurysm

Toward modeling the effects of regional material properties on the wall stress distribution of abdominal aortic aneurysms

“…Our computational workflow consists of two components which have been described in detail in [6]. The former component uses commercial software to construct a 3D mesh model of the AAA from clinical quality CT or MRI images (Figure 1b, c).…”

“…The former component uses commercial software to construct a 3D mesh model of the AAA from clinical quality CT or MRI images (Figure 1b, c). In addition, this step includes the evaluation of the geometrical indices that describe the shape and size of the AAA [6]. The latter component consists of the developed finite element model (FEM) using commercial software based on the computational domain extracted from the previous step, along with prescribed biomechanical parameters and loading conditions to analyze the biomechanical behavior of the AAA and compute the wall stress distribution under the prescribed conditions [6] (Figure 1d).…”

“…To mitigate this limitation, a 2-mm uniform wall thickness was prescribed throughout the entire length of the aorta, similar to previous studies [13–15]. To mesh the wall thickness, as part of our FEM[6], we use quadratic hexahedral element (SOLID186 element type in ANSYS), in contrast with previous studies which used either the shell elements (element SHELL93 in ANSYS) or the tri-linear hexahedral element (SOLID185 in ANSYS) [4, 9, 10], with two elements across the thickness (between the outer wall and inner wall of the aorta). This element type is a 20-node element having three degrees of freedom at each node.…”

“…The gradually increasing weakening of the aortic wall due to metabolic activity at the aneurysm site has been introduced as the main reason for AAA development [5, 6]. As such, researchers have pointed that rupture is likely to occur if the overall effective stress developed inside the aortic wall exceeds the mechanical strength of the vessel tissue.…”

“…As such, researchers have pointed that rupture is likely to occur if the overall effective stress developed inside the aortic wall exceeds the mechanical strength of the vessel tissue. For decades, the D max > 5.5 cm criterion has been used as the main diagnostic factor to study AAA severity; however, it has been shown, including our previous study [6], that the peak wall stress along with the whole geometry of the AAA provides a more reliable indicator of the rupture. Moreover, it was shown that the rupture site is related to the location of the AAA where the PWS occurs [5–7]; hence, this AAA rupture criterion can be implemented and estimated using biomechanical parameters such as peak wall stress (PWS), especially for aneurysms with D max <5.5 cm.…”