scholarly journals Numerical investigation of hemodynamic performance of a stent in the main branch of a coronary artery bifurcation

Bioimpacts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 97-103 ◽  
Author(s):  
Seyed Esmail Razavi ◽  
Vahid Farhangmehr ◽  
Zahra Babaie
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Software Package ◽  
Three Dimensional ◽  
Bare Metal Stent ◽  
Side Branch ◽  
Commercial Software ◽  
Before And After ◽  
Commercial Software Package ◽  
Hemodynamic Performance

Introduction: The effect of a bare-metal stent on the hemodynamics in the main branch of a coronary artery bifurcation with a particular type of stenosis was numerically investigated by the computational fluid dynamics (CFD). Methods: Three-dimensional idealized geometry of bifurcation was constructed in Catia modelling commercial software package. The Newtonian blood flow was assumed to be incompressible and laminar. CFD was utilized to calculate the shear stress and blood pressure distributions on the wall of main branch. In order to do the numerical simulations, a commercial software package named as COMSOL Multiphysics 5.3 was employed. Two types of stent, namely, one-part stent and two-part stent were applied to prevent the build-up and progression of the atherosclerotic plaques in the main branch. Results: A particular type of stenosis in the main branch was considered in this research. It occurred before and after the side branch. Moreover, it was found that the main branch with an inserted one-part stent had the smallest region with the wall shear stress (WSS) below 0.5 Pa which was the minimum WSS in the main branch without the stenosis. Conclusion: The use of a one-part stent in the main branch of a coronary artery bifurcation for the aforementioned type of stenosis is recommended.

Comparison of Left Anterior Descending Coronary Artery Hemodynamics Before and After Angioplasty

2005 ◽  
Vol 128 (1) ◽  
pp. 40-48 ◽  
Author(s):  
S. D. Ramaswamy ◽  
S. C. Vigmostad ◽  
A. Wahle ◽  
Y.-G. Lai ◽  
M. E. Olszewski ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Fluid Dynamic ◽  
Critical Role ◽  
Three Dimensional ◽  
Cardiac Contraction ◽  
Local Geometry ◽  
Arbitrary Lagrangian Eulerian ◽  
Computational Fluid Dynamic Analysis ◽  
Before And After

Coronary artery disease (CAD) is characterized by the progression of atherosclerosis, a complex pathological process involving the initiation, deposition, development, and breakdown of the plaque. The blood flow mechanics in arteries play a critical role in the targeted locations and progression of atherosclerotic plaque. In coronary arteries with motion during the cardiac contraction and relaxation, the hemodynamic flow field is substantially different from the other arterial sites with predilection of atherosclerosis. In this study, our efforts focused on the effects of arterial motion and local geometry on the hemodynamics of a left anterior descending (LAD) coronary artery before and after clinical intervention to treat the disease. Three-dimensional (3D) arterial segments were reconstructed at 10 phases of the cardiac cycle for both pre- and postintervention based on the fusion of intravascular ultrasound (IVUS) and biplane angiographic images. An arbitrary Lagrangian-Eulerian formulation was used for the computational fluid dynamic analysis. The measured arterial translation was observed to be larger during systole after intervention and more out-of-plane motion was observed before intervention, indicating substantial alterations in the cardiac contraction after angioplasty. The time averaged axial wall shear stress ranged from −0.2to9.5Pa before intervention compared to −0.02to3.53Pa after intervention. Substantial oscillatory shear stress was present in the preintervention flow dynamics compared to that in the postintervention case.

Patient-specific three-dimensional simulation of LDL accumulation in a human left coronary artery in its healthy and atherosclerotic states

2009 ◽  
Vol 296 (6) ◽  
pp. H1969-H1982 ◽  
Author(s):  
Ufuk Olgac ◽  
Dimos Poulikakos ◽  
Stefan C. Saur ◽  
Hatem Alkadhi ◽  
Vartan Kurtcuoglu
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Left Coronary Artery ◽  
Three Dimensional ◽  
Arterial Blood Flow ◽  
Patient Specific ◽  
Computed Tomography Images ◽  
Arterial Blood ◽  
Diseased State ◽  
Stress Dependent

We calculate low-density lipoprotein (LDL) transport from blood into arterial walls in a three-dimensional, patient-specific model of a human left coronary artery. The in vivo anatomy data are obtained from computed tomography images of a patient with coronary artery disease. Models of the artery anatomy in its healthy and diseased states are derived after segmentation of the vessel lumen, with and without the detected plaque, respectively. Spatial shear stress distribution at the endothelium is determined through the reconstruction of the arterial blood flow field using computational fluid dynamics. The arterial endothelium is represented by a shear stress-dependent, three-pore model, taking into account blood plasma and LDL passage through normal junctions, leaky junctions, and the vesicular pathway. Intraluminal pressures of 70 and 120 mmHg are employed as the normal and hypertensive operating pressures, respectively. By applying our model to both the healthy and diseased states, we show that the location of the plaque in the diseased state corresponds to one of the two sites with predicted high-LDL concentration in the healthy state. We further show that, in the diseased state, the site with high-LDL concentration has shifted distal to the plaque, which is in agreement with the clinical observation that plaques generally grow in the downstream direction. We also demonstrate that hypertension leads to increased number of regions with high-LDL concentration, elucidating one of the ways in which hypertension may promote atherosclerosis.

Calculations of intensities for radiation force modeling with the commercial software package FOCUS.

2010 ◽  
Vol 127 (3) ◽  
pp. 1828-1828
Author(s):  
Robert J. McGough ◽  
Donald J. Vanderlaan ◽  
Alexander Dutch ◽  
Matthew W. Urban
Keyword(s):  
Software Package ◽  
Radiation Force ◽  
Commercial Software ◽  
Force Modeling ◽  
Commercial Software Package

Masonry Column Reinforced by FRP Wrapping: Behavior and Numerical Analysis

2016 ◽  
Vol 825 ◽  
pp. 27-30 ◽  
Author(s):  
Aneta Maroušková
Keyword(s):  
Numerical Analysis ◽  
Software Package ◽  
Unreinforced Masonry ◽  
Numerical Results ◽  
Experimental Program ◽  
Research Project ◽  
Commercial Software ◽  
Non Linear ◽  
Commercial Software Package ◽  
Frp Wrapping

A numerical analysis for masonry columns is presented in this paper. The behavior and character of deformation of compressed unreinforced masonry columns is investigated and compared with the deformation of masonry columns reinforced by FRP wrapping. The experimental program is part of a research project NAKI [1]. Both, the bricks and the mortar are modeled as 3D continuum and to the interface between these two materials a non-linear contact law is assigned. The contact between reinforcement and masonry support is considered as perfectly-adherent. Two different cases are simulated - the ratio of Young ́s modulus of brick and Young’s modulus of mortar is 5:1, respectively 1:5. For all simulations the commercial software package ABAQUS was used and the obtained numerical results are discussed.

Abstract 1635: In Vivo Color Mapping Of Shear Stress Along Coronary Arterial Lumen With Multi-detector Computed Tomography

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Yusaku Fukumoto ◽  
Takafumi Hiro ◽  
Takashi Fujii ◽  
Mitsuyuki Hiromoto ◽  
Masakazu Tanaka ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Shear Stress ◽  
Coronary Artery ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Plaque Formation ◽  
Color Mapping ◽  
Atherosclerotic Plaque Formation ◽  
Multi Detector Computed Tomography

Background and Purpose: Shear stress is one of the important physical factors in the process of atherosclerosis. However, noninvasive and in-vivo visualization of shear stress distribution along the coronary lumen has been technically difficult, because it is not so possible to assess true three-dimensional (3D) geometrical structure as well as local flow profile in coronary artery for each patient. Recent technology of multi-detector computed tomography (MDCT) can provide an accurate representation of 3D architecture of coronary lumen as well as plaque distribution. This study was to develop a noninvasive way of color mapping of shear stress in coronary artery using a 64-row MDCT, and to preliminarily evaluate its clinical feasibility. Methods: Three-dimensional geometric architecture from patients with mild coronary artery disease was first obtained to develop a 3D mesh polygon model of each left and right coronary artery architecture. The mesh data was then used to perform a shear stress color mapping with a computational fluid-dynamical simulation of finite element model. The spatial resolution ( mesh size ) was 0.05 mm 2 . The flow was considered to be a constant laminar one, and the pulsatile motion was neglected. The relationship between shear stress and plaque accumulation was then examined. Results: According to the MDCT, atherosclerotic plaque formation was frequently observed in the distal potion at the first and second curvature of right coronary artery, and in the outer side of the bifurcation of the left anterior descending and the circumflex coronary artery. The colorized mapping of shear stress revealed that shear stress tended to be lower at the site of plaque accumulation within coronary artery. Conclusion: This method of 3D representation of shear stress distribution along coronary lumen with a 64-row MDCT might be useful for assessing the role of shear stress in atherosclerotic plaque formation or its progression / regression.

Numerical Analysis of Steady Flow in Aorto-Coronary Bypass 3-D Model

1996 ◽  
Vol 118 (2) ◽  
pp. 172-179 ◽  
Author(s):  
Fabio Inzoli ◽  
Francesco Migliavacca ◽  
Giancarlo Pennati
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Intimal Hyperplasia ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Coronary Bypass ◽  
Secondary Flows ◽  
Geometrical Parameters ◽  
Shear Stresses

Intimal hyperplasia and atherosclerosis have a predominant role in the failure of coronary artery bypass procedures. Theoretical studies and in vivo observations have shown that these pathologies are much more likely to occur in the proximity of end-to-side anastomosis, thus indicating that fluid dynamic conditions may be included in the pathogenic causes of the initiation, progression and complication of intimal hyperplasia. In order to study the fluid dynamics at the anastomosis of an aorto-coronary bypass, a three-dimensional mathematical model based on a FEM approach was developed. Steady-state simulations were studied in two different geometrical models of anastomosis which differ in their insertion angles (45 and 60 degree). Flow fields with three-dimensional helical patterns, secondary flows, and shear stresses were also investigated. The results show the presence of low shear stresses on the top wall just beyond the toe of the anastomosis and in the region of the coronary artery before the junction. A high wall shear stress region is present on the lateral wall of the coronary artery immediately downstream from the anastomosis. The influence of flow rate distribution on the secondary flows is also illustrated. These results confirm the sensitivity of flow behavior to the model’s geometrical parameters and enhance the importance of reproducing the anastomosis junction as closely as possible in order to evaluate the effective shear stress distribution.

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