3.5 Investigating the Role of Hemodynamics in Aaa Formation Through Combined Imaging and Modeling: A Longitudinal In-Vivo Study in Apoe Mice

The pathophysiological mechanisms underlying abdominal aortic aneurysm (AAA) formation are not yet fully understood. Hemodynamics have been suggested to play an important (modulating) role, but no longitudinal studies have been performed yet due to (a.o.) a lack of (human) data in the pre-diseased state. We used an established mouse model of AAA to perform a longitudinal hemodynamical study in 10 male apoE- deficient mice. All animals were scanned at baseline using micro-CT (Triumph, Gamma Medica) with a dedicated contrast agent (Aurovist, Nanoprobes) to assess the AA geometry, immediately followed by a baseline ultrasound scan (Vevo 2100, Visualsonics) to assess aortic structures and diameters and to measure Doppler velocity waveforms at the proximal and distal aorta and at the celiac, mesenteric, left and right renal arteries. All animals subsequently underwent implantation of a subcutaneous pump , continuously delivering angiotensin || for 28 days. End stage micro-CT and ultrasound scans were performed 31 days after pump implantation. Eight animals survived the complete experiment, and 5 of them developed an AAA. The micro-CT images were subsequently used to reconstruct a geometric 3D computer model (Mimics, Materialise) and combined with the measured flows in a Computational Fluid Dynamics (CFD) simulation (Fluent, Ansys). This procedure will provide unique data on the pre- and post-AAA hemodynamic situation (blood flow and wall shear stress patterns) over the abdominal aorta and side branches in great detail and will allow to further analyze the potential link between local hemodynamics, AAA formation and the location at which the aneurysm develops.