Computational Fluid Dynamic Analysis in Infrarenal Abdominal Aortic Aneurysm for Surveillance of Aneurysm Rupture

Abdominal aortic aneurysm (AAA) disease is mostly infrarenal. Mortality increases with rupture. The main risk factors for rupture are diameter sac and hypertension. Computational fluid dynamic (CFD) analysis of blood flow allows for the detection of where the rupture area will occur. Wall shear stress (WSS) and wall pressure are parameters that can be analyzed through CFD to see the potential location for rupture in AAA. The aim of the study is to know the morphology of infrarenal AAA along with the distribution of WSS values and aneurysmal wall pressure based on CFD to predict aneurysm rupture. This is a cross-sectional study with computed tomography (CT) angiogram analysis of patients with infrarenal AAA in the Vascular and Endovascular Division-Department of Surgery and the Department of Radiology Cipto Mangunkusumo Hospital in July-December 2022. CT-angiography data were processed with Radiant Viewer to be used as a 3D model. The sample is grouped into five types of aneurysms. Then for each model, the process of making a solid vessel is carried out with Meshmixer. The next process involves geometry, meshing, CFD parameter setup, and solutions to produce WSS and wall pressure contours at various speeds and blood pressures with the ANSYS 2022 R2 Academic Student program. Visual results for each type were analyzed and compared. WSS and wall pressure nonparametric tests were performed for each type and between groups using SPSS 25.0 with a P value considered significant if <.05. Of the 93 CT angiograms, after exclusion, 40 samples were obtained. The median age was 67 (47-76) years, with 90% men. As much as 25% of the sample had a saccular component. The results of the visual analysis showed that there was an area correlation between the lowest WSS and the highest wall pressure. Changes in velocity and initial blood pressure also changed the value and area of the WSS and the aortic wall pressure contours, although the center of the contour change was still in the relatively same area. There was a significant difference in WSS and wall pressure (P = .038 and P < .001). The area of the lowest WSS corresponds to the location of the highest wall pressure and could be predicted as the site of an aneurysm rupture. Changes in blood velocity and pressure affect the area and value of WSS and wall pressure. Surveillance in the area with the lowest WSS should be given more attention.