Hemodynamic Abnormalities in Stented Carotid Artery: A Fluid Structure Interaction Study

2012 ◽  
Author(s):  
Thomas A. Metzger ◽  
Santanu Chandra ◽  
Philippe Sucosky
Keyword(s):  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Stent Implantation ◽  
Arterial Wall ◽  
Fluid Structure Interaction ◽  
Normal Model ◽  
Stent Angioplasty ◽  
Structure Interaction ◽  
Wall Shear

Balloon-stented angioplasty is a common treatment for carotid arterial atherosclerosis. Clinical studies have shown that within 6 months of the initial procedure, 25% of stented-angioplasty patients develop restenosis, a postoperative narrowing of the artery due to plaque accumulation onto the stent. While hemodynamics and more specifically low oscillatory wall-shear stress have been identified as key factors promoting atherogenesis, their role in restenosis following stent implantation remains unclear. We hypothesize that the implantation of a stent generates hemodynamic abnormalities consisting of low wall shear stresses in the vicinity of arterial wall regions prone to restenosis. The objective of this study was to compare computationally the hemodynamics in normal (healthy), stenosed (atherosclerotic) and stented carotid artery bifurcation models and to investigate potential correlations between regions presenting high hemodynamic abnormalities and regions prone to postoperative stent angioplasty restenosis. Realistic, three-dimensional models of normal, stenosed and stented human carotid bifurcations consisting of the common (CCA), external (ECA) and internal (ICA) carotid arteries were developed using the computer-assisted design software Solid Edge. The characteristic dimensions of the normal and stenosed models were obtained from previously published human data. The stented model was designed by modeling the inner surface of the ICA bulb region as a rigid cylindrical surface mimicking the presence of a stent. Fluid-structure interaction (FSI) simulations were carried out using the adaptive arbitrary Lagrangian Eulerian (ALE) approach of ANSYS 14 to simulate flow and arterial wall dynamics in each model subjected to physiologic pressure and flow rate. As expected, the atherosclerotic model resulted in higher velocity and wall shear stress (WSS) levels than the normal model due to the reduced ICA lumen. In addition, while stent implantation restored the hemodynamic performance of the vessel, it generated lower WSS than in the normal model, which may contribute to restenosis. This study provides new insights into the possible hemodynamic roots of postoperative stent angioplasty restenosis.

scholarly journals Fluid–structure interaction analysis of hemodynamics in different degrees of stenoses considering microcirculation function

2021 ◽  
Vol 13 (1) ◽  
pp. 168781402198901
Author(s):  
Fan He ◽  
Lu Hua ◽  
Tingting Guo
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Arterial Wall ◽  
Interaction Analysis ◽  
Fluid Structure Interaction ◽  
Developed Countries ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Simulation Based ◽  
Wall Shear

In developed countries, stenosis is the main cause of death. To investigate hemodynamics within different degrees of stenoses, a stenosis model incorporating fluid–structure interaction and microcirculation function is used in this paper. Microcirculation is treated as a seepage outlet boundary condition. Compliant arterial wall is considered. Numerical simulation based on fluid–structure interaction is performed using finite element method. Our results indicate that (i) the increasing degree of stenosis makes the pressure drop increase, and (ii) the wall shear stress and the velocity in the artery zone may be more sensitive than the pressure with the increase of percentage stenosis, and (iii) there are higher wall shear stress and flow velocity in the post-stenosis region of severer stenosis. This work contributes to understand hemodynamics for different degrees of stenoses and it provides detailed information for stenosis and microcirculation function.

scholarly journals Numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Fan He ◽  
Lu Hua ◽  
Tingting Guo
Keyword(s):  
Numerical Modeling ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Fluid Structure Interaction ◽  
Rigid Wall ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Arterial Hemodynamics ◽  
Wall Compliance ◽  
Wall Shear

Abstract Background The effects of arterial wall compliance on blood flow have been revealed using fluid-structure interaction in last decades. However, microcirculation is not considered in previous researches. In fact, microcirculation plays a key role in regulating blood flow. Therefore, it is very necessary to involve microcirculation in arterial hemodynamics. Objective The main purpose of the present study is to investigate how wall compliance affects the flow characteristics and to establish the comparisons of these flow variables with rigid wall when microcirculation is considered. Methods We present numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation. A novel outlet boundary condition is employed to prescribe microcirculation in an idealised model. Results The novel finding in this work is that wall compliance under the consideration of microcirculation leads to the increase of wall shear stress in contrast to rigid wall, contrary to the traditional result that wall compliance makes wall shear stress decrease when a constant or time dependent pressure is specified at an outlet. Conclusions This work provides the valuable study of hemodynamics under physiological and realistic boundary conditions and proves that wall compliance may have a positive impact on wall shear stress based on this model. This methodology in this paper could be used in real model simulations.

Numerical CFD / FSI Study of Teflon and Dacron for Use in the Femoral Artery Graft Procedure

2019 ◽  
Author(s):  
Sukwinder Sandhu ◽  
Kevin R. Anderson
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Femoral Artery ◽  
Hoop Stress ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Implant Materials ◽  
Artery Graft ◽  
Wall Shear

Abstract This paper presents Fluid Structure Interaction modeling of candidate implant materials used in the femoral artery graft medical procedure. Two candidate implant materials, namely Teflon and Dacron are considered and modeled using Computational Fluid Dynamics (CFD) and structural Finite Element Analysis (FEA) to obtain Fluid Structure Interaction (FSI) developed stresses within the candidate materials as a result of non-Newtonian blood flowing in a pulsatile unsteady fashion into the femoral artery implant tube. The pertinent findings for a pulsatile velocity maximum magnitude of 0.3 m/s and period of oscillation of 2.75 sec are as follows. For the biological tissue the wall shear stress is found to be 2.15 × 104 Pa, the hoop stress is found to be 1.6 × 104 Pa. For the Teflon implant material, the wall shear stress is found to be 1.177 × 104 Pa, the hoop stress is found to be 2.2 × 104 Pa. For the Dacron implant material the wall shear stress is found to by 3.9 × 104 Pa, the hoop stress is found to be 2.17 × 104 Pa. Based upon the analysis herein the PTFE material would be recommended.

Increase of wall shear stress caused by arteriovenous fistula reduces neointimal hyperplasia after stent implantation in healthy arteries

Vascular ◽  
2020 ◽  
Vol 28 (4) ◽  
pp. 396-404
Author(s):  
Chong Dong Liu ◽  
Feng Chen
Keyword(s):  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Arteriovenous Fistula ◽  
Common Carotid Artery ◽  
Stent Implantation ◽  
Neointimal Hyperplasia ◽  
Stent Group ◽  
Wall Shear ◽  
Endothelial Nitric Oxide

Background and objectives Wall shear stress plays a critical role in neointimal hyperplasia after stent implantation. It has been found that there is an inverse relation between wall shear stress and neointimal hyperplasia. This study hypothesized that the increase of arterial wall shear stress caused by arteriovenous fistula could reduce neointimal hyperplasia after stents implantation. Methods and results Thirty-six male rabbits were randomly divided into three groups: STENT, rabbits received stent implantation into right common carotid artery; STENT/arteriovenous fistula, rabbits received stent implantation into right common carotid artery and carotid-jugular arteriovenous fistula; Control, rabbits received no treatment. After 21 days, stented common carotid artery specimens were harvested for histological staining and protein expression analysis. In STENT group, wall shear stress maintained at a low level from 43.2 to 48.9% of baseline. In STENT/arteriovenous fistula group, wall shear stress gradually increased to 86% over baseline. There was a more significant neointimal hyperplasia in group STENT compared with the STENT/arteriovenous fistula group (neointima area: 0.87 mm2 versus 0.19 mm2; neointima-to-media area ratio: 1.13 versus 0.18). Western blot analysis demonstrated that the protein level of endothelial nitric oxide synthase in STENT group was significantly lower than that in STENT/arteriovenous fistula group, but the protein levels of proliferating cell nuclear antigen, vascular cell adhesion molecule 1, phospho-p38 mitogen-activated protein kinase (Pp38), and phospho-c-Jun N-terminal kinase in STENT group were significantly higher than that in the STENT group. Conclusion High wall shear stress caused by arteriovenous fistula as associated with the induction in neointimal hyperplasia after stent implantation. The underlying mechanisms may be related to modulating the expression and activation of endothelial nitric oxide synthase, vascular cell adhesion molecule 1, p38, and c-Jun N-terminal kinase.

Wall Shear Stress in an MRI-Based Subject-Specific Human Aorta Using Fluid-Structure Interaction

2010 ◽  
Author(s):  
Jonas Lantz ◽  
Johan Renner ◽  
Matts Karlsson
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Thrombus Formation ◽  
Fluid Structure Interaction ◽  
Human Aorta ◽  
Shear Stresses ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Increased Risk ◽  
Wall Shear

Wall shear stress (WSS) is well established as an indicator of increased risk for development of atherosclerotic plaques, platelet activation and thrombus formation [1]. Prediction and simulation of the sites of wall shear stresses that are deemed dangerous before intervention would be of great aid to the surgeon. However, the geometries used for these types of simulations are often approximated to be rigid. To more accurately capture the flow and arterial wall response of a realistic human aorta, fluid-structure interaction (FSI) which allows movement of the wall, is needed. Hence, the pressure wave and its effect on the wall motion are resolved and enables a more physiological model as compared to a rigid wall case.

MODELING OF SUPERIOR MESENTERIC ARTERY ANEURYSM USING FLUID–STRUCTURE INTERACTION

2015 ◽  
Vol 15 (01) ◽  
pp. 1550005
Author(s):  
BAHARAK EBRAHIMI ◽  
KAMRAN HASSANI
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Wall Shear Stress ◽  
Superior Mesenteric Artery ◽  
Mesenteric Artery ◽  
Cardiac Cycle ◽  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Wall Shear

The aim of this study was to model the blood flow and predict related hemodynamics characteristics in healthy superior mesenteric artery (SMA) and saccular aneurysm cases. A fluid–structure interaction (FSI) method was performed, using an arbitrary Langrangian–Eulerian mesh. The computational mesh was generated using anatomical data from available human computed tomography (CT)-images. Combining constitution and momentum equations, projection method, the discretized resultant equation were numerically solved for velocity, pressure, shear stress and vortices for healthy/aneurysmal artery. The results including velocity contours, pressure contours, shear rate values, and vortices were obtained and analyzed for three main steps including peak systole, diastole, and end of cardiac cycle. Profiles show the varying velocity and pressure for a pulsatile flow input before and after aneurysms. They also show the formation of single or multiple vortices at aneurysmal area and decrease of wall shear stress with aneurysm enlargement. Furthermore, shear rate values at the neck of aneurysms exceed throughout the entire cardiac cycle. The outcome of the computational analysis is then compared to information available on pressure, vortices and wall shear stress from some clinical findings.

Basic study on estimation method of wall shear stress in common carotid artery using blood flow imaging

2020 ◽  
Vol 59 (SK) ◽  
pp. SKKE16 ◽  
Author(s):  
Ryo Nagaoka ◽  
Kazuma Ishikawa ◽  
Michiya Mozumi ◽  
Magnus Cinthio ◽  
Hideyuki Hasegawa
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Common Carotid Artery ◽  
Estimation Method ◽  
Flow Imaging ◽  
Basic Study ◽  
Blood Flow Imaging ◽  
Wall Shear
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