Abdominal Aortic Aneurysm
(From the Cardiovascular Dynamics DBP led by Charles A. Taylor, Ph.D. and Christopher K Zarins, M.D.)
We have created subject-specific models of an abdominal aortic aneurysm (AAA), including the renal arteries feeding the kidneys, the celiac and superior mesenteric arteries feeding the viscera, and the iliac arteries, including the internal iliac arteries.
Blood velocity and pressure fields in large arteries are greatly influenced by the deformability of the vessel. However, computational methods for simulating blood flow in three-dimensional models of arteries have either assumed a rigid wall for the vessel or significantly simplified geometries. For large, realistic anatomic and physiologic models of the cardiovascular system, it remains a formidable problem to compute blood flow in deformable domains using standard techniques like the ALE (Arbitrarily Lagrangian - Eulerian) method.
We have developed a new method to simulate blood flow in three-dimensional defomable models of arteries. The method couples the equations of the deformation of the vessel wall at the variational level as a boundary condition for the fluid domain. We consider a strong coupling of the degrees-of-freedom of the fluid and the solid domains. The effect of the vessel wall boundary is therefore added in a monolithic way to the fluid equations, resulting in a remarkably robust scheme.
Figure: Pressure, wall displacement and blood velocity in a subject-specific AAA model under exercise conditions. Blood pressure and velocity magnitude (along a slice plane) are shown at peak systole.