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.

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.

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.

scholarly journals Single-cell RNA-seq reveals a critical role of novel pro-inflammatory EndMT in mediating adverse remodeling in coronary artery–on–a–chip

2021 ◽  
Vol 7 (34) ◽  
pp. eabg1694
Author(s):  
Peng Zhao ◽  
Qingzhou Yao ◽  
Pei-Jian Zhang ◽  
Erlinda The ◽  
Yufeng Zhai ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Single Cell ◽  
Critical Role ◽  
Three Dimensional ◽  
Human Coronary Artery ◽  
Mesenchymal Transition ◽  
Signaling Axis ◽  
Endothelial To Mesenchymal Transition

A three-dimensional microengineered human coronary artery–on–a–chip was developed for investigation of the mechanism by which low and oscillatory shear stress (OSS) induces pro-atherogenic changes. Single-cell RNA sequencing revealed that OSS induced distinct changes in endothelial cells (ECs) including pro-inflammatory endothelial-to-mesenchymal transition (EndMT). OSS promoted pro-inflammatory EndMT through the Notch1/p38 MAPK–NF-κB signaling axis. Moreover, OSS-induced EC phenotypic changes resulted in proliferation and extracellular matrix (ECM) protein up-regulation in smooth muscle cells (SMCs) through the RANTES-mediated paracrine mechanism. IL-37 suppressed OSS-induced pro-inflammatory EndMT and thereby abrogated SMC proliferation and ECM protein remodeling. Overall, this study provides insights into endothelial heterogeneity under atheroprone shear stress and identifies the mechanistic role of a novel EC subtype in promoting adverse vascular remodeling. Further, this study demonstrates that anti-inflammatory approach is capable of mitigating vascular pathobiology evoked by atheroprone shear stress.

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.

scholarly journals Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Osama N. Alshroof ◽  
Gareth L. Forbes ◽  
Nader Sawalhi ◽  
Robert B. Randall ◽  
Guan H. Yeoh
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Moving Boundary ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Commercial Software ◽  
Computational Fluid Dynamic Analysis ◽  
Current State ◽  
Blade Tip ◽  
The One

This study presents the numerical fluid-structure interaction (FSI) modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i) discussion of the current state of the art of modelling FSI in gas turbine engines and (ii) development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.

An Experimental/Computational Study of Airflow in the Combustor–Diffuser System of a Gas Turbine for Power Generation

1998 ◽  
Vol 120 (1) ◽  
pp. 24-33 ◽  
Author(s):  
A. K. Agrawal ◽  
J. S. Kapat ◽  
T. T. Yang
Keyword(s):  
Gas Turbines ◽  
Computational Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Strong Interactions ◽  
Test Model ◽  
Computational Fluid Dynamic Analysis ◽  
Flow Measurements ◽  
Venturi Effect

This paper presents an experimental/computational study of cold flow in the combustor–diffuser system of industrial gas turbines employing can-annular combustors and impingement-cooled transition pieces. The primary objectives were to determine flow interactions between the prediffuser and dump chamber, to evaluate circumferential flow nonuniformities around transition pieces and combustors, and to identify the pressure loss mechanisms. Flow experiments were conducted in an approximately one-third geometric scale, 360-deg annular test model simulating practical details of the prototype including the support struts, transition pieces, impingement sleeves, and can-annular combustors. Wall static pressures and velocity profiles were measured at selected locations in the test model. A three-dimensional computational fluid dynamic analysis employing a multidomain procedure was performed to supplement the flow measurements. The complex geometric features of the test model were included in the analysis. The measured data correlated well with the computations. The results revealed strong interactions between the prediffuser and dump chamber flows. The prediffuser exit flow was distorted, indicating that the uniform exit conditions typically assumed in the diffuser design were violated. The pressure varied circumferentially around the combustor casing and impingement sleeve. The circumferential flow nonuniformities increased toward the inlet of the turbine expander. A venturi effect causing flow to accelerate and decelerate in the dump chamber was also identified. This venturi effect could adversely affect impingement cooling of the transition piece in the prototype. The dump chamber contained several recirculation regions contributing to the losses. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor–diffuser, much of it in the dump chamber where the fluid passed though narrow pathways. A realistic test model and three-dimensional analysis used in this study provided new insight into the flow characteristics of practical combustor–diffuser systems.

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.

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