Investigation of the hemodynamic flow conditions and blood‐induced stresses inside an abdominal aortic aneurysm by means of a SPH numerical model

The estimation of blood flow–induced loads occurring on the artery wall is affected by uncertainties hidden in the complex interaction of the pulsatile flow, the mechanical parameters of the artery, and the external support conditions. To circumvent these difficulties, a specific tool is developed by combining the aorta displacements measured by an electrocardiogram‐gated–computed tomography angiography, with the blood velocity field computed by a smoothed particle hydrodynamics (SPH) numerical model. In the present work, the SPH model has been specifically adapted to the solution of the 3D Navier–Stokes equations inside a domain with boundaries of prescribed motion. Images of the abdominal aorta aneurysm (AAA) of a 44‐year‐old female patient were acquired during a stabilized cardiac cycle by electrocardiogram‐gated–computed tomography angiography. The in vivo kinematic field inside the pulsating arterial wall was estimated by using recent technology, which makes it possible to follow the shape of the arterial wall during a cardiac cycle. We compare the flow conditions and the blood‐induced loads, computed by the numerical model under the assumption of a moving arterial wall, with the corresponding results obtained assuming three rigid wall geometries of the vessel during the cardiac cycle. Significant differences were found for the wall shear stress distribution. We propose a new in vivo, noninvasive tool to predict the flow field and the blood‐induced loads for any patient‐specific abdominal aortic aneurysms. The tool combines a numerical SPH model, specifically adapted to the case of mobile boundaries, with a numerical methodology that estimates the aortic wall displacements from available ECG‐gated CTA. The WSS vectors and their spatial/temporal gradients obtained for moving wall geometry are significantly smaller than those of rigid wall cases, computed for the same patient‐specific case.