Arij Debbich

Bio: Arij Debbich is an academic researcher from University of Monastir. The author has contributed to research in topics: Internal carotid artery & Blood flow. The author has an hindex of 1, co-authored 4 publications receiving 5 citations.

Blood Flow Modeling in a Healthy Carotid Artery Bifurcation: Simulations Against in Vivo Measurements

Abstract: This paper deals with the hemodynamic modeling in a carotid artery bifurcation with two laws - the laminar Newtonian and non Newtonian blood flow models- and two velocity inlet conditions - uniform and parabolic -. We assumed that blood flow is laminar and incompressible and the wall is rigid. From the artery geometry and the inlet velocity profile, four hemodynamic models of pulsatile flow were performed. These models were tested on a healthy subject data. The vascular model was reconstructed from Computed Tomography Angiography acquisition. The Doppler Ultrasound velocity data provided were considered as references. As a first conclusion, in the internal carotid artery, simulated velocities with non Newtonian law and uniform velocity inlet were the closest to US-Doppler measurements. However, in the external carotid artery, the closest model to US-Doppler measurements was non Newtonian law with parabolic inlet. Overall, Newtonian and non Newtonian blood flow models had a close behavior.

Hemodynamic Modeling in a Stenosed Internal Carotid Artery

Abstract: This paper deals with patient-specific blood flow modeling in a stenosed internal carotid artery (ICA) An ICA stenosis has an impact on hemodynamic behavior It can hamper the brain irrigation and even cause a stroke Our aim is to predict the blood flow behavior through computational fluid dynamic (CFD) study The proposed approach realizes a hemodynamic modeling within a geometric carotid model build from a 3D computed tomography angiography image with blood considered as a Newtonian and incompressible fluid, and the wall as rigid The blood flow modeling is based on the Navier-Stokes equation A Womersley velocity profile is used as a boundary condition in the common carotid artery Main results of this study are the following: (1) velocity is maximum in stenosis and minimum in the sinus, (2) pressure is negative on the most of carotid artery bifurcation unless the post-stenotic site

Effect of Surface Re-Meshing on Hemodynamic Simulations Quality in Carotid Arteries

Abstract: In this paper we present an approach to quantify the effect of surface re-meshing on hemodynamic modeling. This work is organized in three parts. First, we briefly present the basic concepts inherent in hemodynamic modeling. Then, we detail the approach of triangular surface re-meshing: simplification and local densification based on discrete curvature analysis. The re-meshed triangular surfaces are used as input as well as a parabolic inlet velocity profile to the hemodynamic modeling procedure. As a validation, the third part will be focused on two examples: carotid blood flow characterization for a healthy patient and one with stenosis in the carotid artery. We quantified the differences between the generated models by evaluating the Eucledean similarity, rate of change and RMSE between the measured and modeled velocity obtained with different mesh densities. We conclude with the important effect of re-meshing on the modeled results and we propose to adapt the choice of the localization and the proportion of re-meshing to the local deformation of arterial structure.

A computational model for cardiovascular hemodynamics and protein transport phenomena

Abstract: The hemodynamics plays a key role in the transport processes, in the blood stream, and thus, on the accumulation and deposition of lipids and medication on the vessel’s wall. Therefore, understanding the hemodynamics of the arterial veins can advance the understanding of transport phenomena and prediction of deposition and buildup of the low-density lipoproteins (LDL) and particulate medication, on the arterial surfaces. Previous studies have showed that for pulsatile flow, laminar-turbulent flow transition may occur, particularly during intense exercises. Experimental and computational studies, of hemodynamics and transport phenomena, pose significant challenges due to the complex aorta’s geometry and arterial fluid dynamics. In the present study, we propose a large-eddy simulation (LES), computational approach, to carry out the hemodynamics and medication dispersion and deposition studies, inside the descending aorta. The analysis reveals that the flow separation causes a preferential deposition and build-up of low-density lipoproteins (LDL) on the arterial surface. Our study also shows that the flow boundary-layer separation is associated with an increase in deposition of the low-density lipoproteins. The analysis reveals the presence of Dean vortices, inside the aorta branches, which contribute to the reduction of the deposition and build-up of low-density lipoproteins on the arterial surfaces. The analysis of medication dispersion and deposition, inside the descending aorta, shows that the total medication deposition increases with the increase of particle size and density. Particles of fiber-like shape are more prone to deposition, and this is due to the fact that fiber-like particles align perfectly with the flow streamlines. Thus, the interaction of complex turbulent eddies with vessel’s wall causes medication deposition. The research shows that LES is a promising tool in the analysis of hemodynamics and medication transport and therefore, it may assist medical planning by providing surgeons with the elements of the blood flow such as, pressure, velocity, vorticity, wall-shear stresses, which cannot be measured in vivo and obtained with imaging techniques.

Non‐invasive MR imaging techniques for measuring femoral arterial flow in a pediatric and adolescent cohort

Abstract: Magnetic Resonance Imaging (MRI) is well‐suited for imaging peripheral blood flow due to its non‐invasive nature and excellent spatial resolution. Although MRI is routinely used in adults to assess physiological changes in chronic diseases, there are currently no MRI‐based data quantifying arterial flow in pediatric or adolescent populations during exercise. Therefore the current research sought to document femoral arterial blood flow at rest and following exercise in a pediatric‐adolescent population using phase contrast MRI, and to present test‐retest reliability data for this method. Ten healthy children and adolescents (4 male; mean age 14.8 ± 2.4 years) completed bloodwork and resting and exercise MRI. Baseline images consisted of PC‐MRI of the femoral artery at rest and following a 5 × 30 s of in‐magnet exercise. To evaluate test‐retest reliability, five participants returned for repeat testing. All participants successfully completed exercise testing in the MRI. Baseline flow demonstrated excellent reliability (ICC = 0.93, p = 0.006), and peak exercise and delta rest‐peak flow demonstrated good reliability (peak exercise ICC = 0.89, p = 0.002, delta rest‐peak ICC = 0.87, p = 0.003) between‐visits. All three flow measurements demonstrated excellent reliability when assessed with coefficients of variance (CV’s) (rest: CV = 6.2%; peak exercise: CV = 7.3%; delta rest‐peak: CV = 7.1%). The mean bias was small for femoral arterial flow. There was no significant mean bias between femoral artery flow visits 1 and 2 at peak exercise. There were no correlations between age or height and any of the flow measurements. There were no significant differences between male and female participants for any of the flow measurements. The current study determined that peripheral arterial blood flow in children and adolescents can be evaluated using non‐invasive phase contrast MRI. The MRI‐based techniques that were used in the current study for measuring arterial flow in pediatric and adolescent patients demonstrated acceptable test‐retest reliability both at rest and immediately post‐exercise.