scholarly journals EXPERIMENTAL TESTING AND NUMERICAL MODELLING OF STENTS IN THE CORONARY ARTERIES

2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Nenad Filipović ◽  
Dalibor Nikolić ◽  
Igor Saveljić ◽  
Themis Exarchos ◽  
Oberdan Parodi
Keyword(s):  
Numerical Methods ◽  
Coronary Arteries ◽  
Arterial Wall ◽  
Experimental Testing ◽  
Flow Simulation ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Stent Deployment ◽  
Specific Patient ◽  
Solute Dynamics

In this study, experimental and numerical stent modelling with plaque formation and progression for specific patient in the coronary arteries is described. In the method, section experimental stent testing is firstly described. Then numerical methods with finite element methods are given. Blood flow simulation is described with Navier-Stokes and continuity equation. Blood vessel wall is modelled with nonlinear viscoelastic material properties. The coupling of fluid dynamics and solute dynamics at the endothelium was achieved by the Kedem-Katchalsky equations. The inflammatory process is modelled using three additional reaction-diffusion partial differential equations. In the results section, the examples with rigid and deformable arterial wall with stented and unstented arteries are presented. Effective stress analysis results for stent deployment have been shown. These experimental and numerical methods can give better understanding of stent deployment procedure and arterial wall response in everyday clinical practice.

scholarly journals COMPUTER MODELING OF STENT DEPLOYMENT AND PLAQUE PROGRESSION IN THE CORONARY ARTERIES

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Nenad Filipović ◽  
Velibor Isailović ◽  
Žarko Milosević ◽  
Dalibor Nikolić ◽  
Igor Saveljić ◽  
...  
Keyword(s):  
Blood Flow ◽  
Coronary Arteries ◽  
Mixed Finite Element ◽  
Flow Simulation ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Stent Deployment ◽  
Specific Patient ◽  
Nonlinear Viscoelastic ◽  
Solute Dynamics

In this study stent deployment modeling with plaque formation and pro- gression for specific patient in the coronary arteries are described. State of the art method for the reported investigations of blood flow in the stented arteries is described. In the met- hod section, image segmentation method for arteries with stent is shortly described. Blood flow simulation is described with Navier-Stokes and continuity equation. Blood vessel tis- sue is modeled with nonlinear viscoelastic material properties. The coupling of fluid dynamics and solute dynamics at the endothelium was achieved by the Kedem-Katchalsky equations. The inflammatory process is modeled using three additional reaction-diffusion partial differential equations. Coupled method with mixed finite element and DPD (Dissi- pative Particle Dynamics) method is presented. In the results section, the examples with rigid and deformable arterial wall with stented and unstented arteries are presented. Effecti- ve stress analysis results for stent deployment have been shown. It can be seen that stent reduces wall shear stress significantly after deployment which is caused by opening the artery and reducing the narrowing. Some results for stent deployment model obtained with solver developed under PAK software package. These computer models can make better understanding and preparation of the surgeons for stent deployment in everyday clinical practice.

scholarly journals IMPROVED NUMERICAL MODEL OF THE ARTERIAL WALL APPLIED FOR SIMULATIONS OF STENT DEPLOYMENT WITHIN PATIENT-SPECIFIC CORONARY ARTERIES

2020 ◽  
pp. 1-5
Author(s):  
Tijana Djukic ◽  
Igor Saveljic ◽  
Gualtiero Pelosi ◽  
Oberdan Parodi ◽  
Nenad Filipovic
Keyword(s):  
Blood Flow ◽  
Numerical Model ◽  
Coronary Arteries ◽  
Arterial Wall ◽  
Arterial Stenosis ◽  
Patient Specific ◽  
Stent Deployment ◽  
Normal Blood Flow ◽  
Experimental Values ◽  
Treatment Procedures

Arterial stenosis is the obstruction of normal blood flow that is caused by atherosclerosis. One of the endovascular treatment procedures in this case is the implantation of a stent to restore the blood flow. This study presented an improved numerical model that can precisely simulate the deformation of human arterial wall in coronary arteries, during the stent deployment process. The new model considered the arterial wall as an incompressible, isotropic and hyperelastic material. The material coefficients were defined according to experimental values presented in literature. The accuracy of the numerical model was investigated by comparing the results with follow up data obtained in clinical examination. The small relative and standard deviation error prove that this numerical model can be used to assist clinicians in decision making and treatment planning with reliable predictions of the outcome of the stent deployment procedure.

scholarly journals Longitudinal stent elongation or shortening after deployment in the coronary arteries: which is dominant?

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Magdy Algowhary ◽  
Mohammed Aboel-Kassem F. Abdelmegid
Keyword(s):  
Regression Analysis ◽  
Intravascular Ultrasound ◽  
Coronary Arteries ◽  
Coronary Stents ◽  
Multinomial Regression ◽  
Stent Deployment ◽  
Stent Length ◽  
Multinomial Regression Analysis

Abstract Background Stent manufacturers always record stent shortening data while they do not record stent elongation data. The aim of this study is to identify both stent shortening and elongation occurring after deployment in the coronary arteries and know their percentage. Results The length of coronary stents was measured by intravascular ultrasound (IVUS) by (1) edge-to-edge (E-E) length, measured from the appearance of the first distal strut to the last proximal strut, and (2) area-to-area (A-A) length, measured from the first distal struts seen at more than one IVUS quadrant to the last proximal struts seen at more than one IVUS quadrant. Stent shortening was defined as both E-E and A-A lengths were shorter than the manufacturer box-stated length (shortened group). Stent elongation was defined as both E-E and A-A lengths were longer than the manufacturer box-stated length (elongated group), otherwise unchanged group. Consecutive 102 stents deployed in ischemic patients were included. Stent elongation was detected in 67.6% (69 stents), and shortening was detected in 15.7% (16 stents), while unchanged stents were detected in 16.7% (17 stents). Although the 3 groups had similar box-stated length and predicted foreshortened length, they had significantly different measurements by IVUS, p<0.001 for each comparison. Differences from box-stated length were 1.9±1.4mm, −1.4±0.4mm, and 0.4±0.3mm, respectively, p<0.001. The elongated group had significantly longer differences from the corresponding box-stated and predicted foreshortened lengths, while the shortened group had significantly shorter differences from the corresponding box-stated length and similar foreshortened length. By multinomial regression analysis, the plaque-media area and stent deployment pressure were the independent predictors of the stent length groups, p=0.015 and p=0.026, respectively. Conclusions Change in stent length is not only shortening—as mentioned in the manufacturer documents—but also stent elongation. Stent elongation is dominant, and the most important predictors of longitudinal stent changes are plaque-media area and stent deployment pressure.

Computed Effects of Rotor-Induced Swirl on Brush Seal Performance—Part 2: Bristle Force Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 920-926 ◽  
Author(s):  
M. C. Sharatchandra ◽  
D. L. Rhode
Keyword(s):  
Inclination Angle ◽  
Flow Direction ◽  
Flow Simulation ◽  
Companion Paper ◽  
Navier Stokes ◽  
Brush Seal ◽  
Swirl Flows ◽  
Lift Off ◽  
Square Configuration ◽  
Periodic Module

This paper analytically investigates the aerodynamic bristle force distributions in brush seals used in aircraft gas turbine engines. These forces are responsible for the onset of bristle tip lift-off from the rotor surface which significantly affects brush seal performance. In order to provide an enhanced understanding of the mechanisms governing the bristle force distributions, a full Navier-Stokes flow simulation is performed in a streamwise periodic module of bristles corresponding to the staggered square configuration. As is the case with a companion paper (Sharatchandra and Rhode, 1996), this study has the novel feature of considering the combined effects of axial (leakage) and tangential (swirl) flows. Specifically, the effects of intra-bristle spacing and bristle inclination angle are explored. The results indicate that the lifting bristle force increases with reduced intra-bristle spacing and increased inclination angle. It was also observed that increases in the axial or tangential flow rates increased the force component in the normal as well as the flow direction.

Challenges in Blood Flow Simulation: Numerical Methods and Image Processing Tools

2013 ◽  
Author(s):  
Andrea Dziubek ◽  
Edmond Rusjan ◽  
Bill Thistleton
Keyword(s):  
Blood Flow ◽  
Numerical Methods ◽  
Flow Simulation ◽  
Ocular Blood Flow ◽  
Curved Surfaces ◽  
Vascular Tree ◽  
Discrete Exterior Calculus ◽  
Exterior Calculus ◽  
Front End ◽  
Segmentation Methods

We report on recent results in modeling ocular blood flow (some parts were presented at ARVO 2013 [1]). For this simulations we used discrete exterior calculus based numerical methods. These methods aim to preserve the main features of the original analytical equations and are very suitable for curved surfaces. We will discuss the model and present the numerical methods. We will also give an overview of existing/available segmentation methods to extract the vascular tree from given retina images and our plans how to use them as a front end to our model.

scholarly journals Numerical methods for stiff reaction-diffusion systems

2007 ◽  
Vol 7 (3) ◽  
pp. 515-525 ◽  
Author(s):  
Ching-Shan Chou ◽  
◽  
Yong-Tao Zhang ◽  
Rui Zhao ◽  
Qing Nie ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Reaction Diffusion ◽  
Reaction Diffusion Systems ◽  
Diffusion Systems
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