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

Abstract

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. K E Y W O R D Saneurysm, arterial wall, infrarenal abdominal aorta, moving boundary, shear stresses, SPH | INTRODUCTIONAbdominal aortic aneurysms (AAAs) are localized and permanent dilatation of the infrarenal abdominal aorta. The related health risk is due to thrombus growth and development, rupture of the aortic wall, and degenerative effects of endothelial cells because of alteration of the flow field inside the aortic lumen. 1 The origin and development of AAAs are not clearly understood. The coupling between physiological changes of the intimal and medial layers of the arterial wall and the mechanical stimuli of the hemodynamic stresses acting on the vessel wall could be one of the origins. 2-5 Past studies 6,7 have shown that the "disturbed" flow conditions inside the lumen, such as regions of high and very low values of wall shear stress (WSS), and large temporal and spatial WSS gradients,

Comparative quantification of primary mitral regurgitation by computer modeling and simulated echocardiography

“…However, several researchers, including our group, have shown that it is a promising method in the field of cardiovascular biomechanics. It has been used to study the mitral valve mechanics (47), left ventricular flow (29), TAVR impact on MR (8), and wall shear stress of abdominal aortic aneurysm (1). Because of the limitations of the Abaqus SPH formulation, the small-scale flow features close to the wall boundary may not be accurately resolved.…”