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 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.

The Effect of Flux Dysconnectivity Functions on Concentration Gradients Changes in a Multicomponent Model of Convectional Reaction-Diffusion by the Example of a Neurovascular Unit

2021 ◽  
Vol 413 ◽  
pp. 19-28
Author(s):  
Yaroslav R. Nartsissov
Keyword(s):  
Blood Flow ◽  
Fluid Flow ◽  
Blood Vessels ◽  
High Speed ◽  
Neurovascular Unit ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Concentration Gradients ◽  
Navier Stokes Equation ◽  
Specific Trait

A convectional diffusion of nutrients around the blood vessels in brain occurs in well-structured neurovascular units (NVU) including neurons, glia and micro vessels. A common feature of the process is a combination of a relatively high-speed delivery solution stream inside the blood vessel and a low-speed convectional flow in parenchyma. The specific trait of NVU is the existence of a tight cover layer around the vessels which is formed by shoots (end-feet) of astrocytes. This layer forms so called blood-brain barrier (BBB). Under different pathological states the permeability of BBB is changed. The concentration gradient of a chemical compound in NVU has been modelled using a combination of mathematical description of a cerebral blood flow (CBF) and further 3D diffusion away from the blood vessels borders. The governing equation for the blood flow is the non-steady-state Navier–Stokes equation for an incompressible non-Newtonian fluid flow without buoyancy effects. BBB is modeled by the flux dysconnectivity functions. The velocity of fluid flow in the paravascular space was estimated using Darcy's law. Finally, the diffusion of the nutrient is considered as a convectional reaction-diffusion in a porous media. By the example of glucose, it was shown that increased permeability of BBB yields an increased level of the nutrient even under essential (on 70%) decrease of CBF. Contrarily, a low BBB permeability breeds a decreased concentration level under increased (on 50%) CBF. Such a phenomenon is explained by a smooth enlarge of the direct diffusion area for a blood-to-brain border glucose transport having three-level organization.

scholarly journals Myocardial Perfusion Simulation for Coronary Artery Disease: A Coupled Patient-Specific Multiscale Model

2020 ◽  
Author(s):  
Lazaros Papamanolis ◽  
Hyun Jin Kim ◽  
Clara Jaquet ◽  
Matthew Sinclair ◽  
Michiel Schaap ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Blood Flow ◽  
Coronary Artery ◽  
Coronary Arteries ◽  
Obstructive Coronary Artery Disease ◽  
Flow Simulation ◽  
Multiscale Model ◽  
Patient Specific ◽  
Human Data ◽  
Artery Disease

AbstractPatient-specific models of blood flow are being used clinically to diagnose and plan treatment for coronary artery disease. A remaining challenge is bridging scales from flow in arteries to the micro-circulation supplying the myocardium. Previously proposed models are descriptive rather than predictive and have not been applied to human data. The goal here is to develop a multiscale patient-specific model enabling blood flow simulation from large coronary arteries to myocardial tissue. Patient vasculatures are segmented from coronary computed tomography angiography data and extended from the image-based model down to the arteriole level using a space-filling forest of synthetic trees. Blood flow is modeled by coupling a 1D model of the coronary arteries to a single-compartment Darcy myocardium model. Simulated results on five patients with non-obstructive coronary artery disease compare overall well to [$$^{15}$$ 15 O]$$\text {H}_{{2}}$$ H 2 O PET exam data for both resting and hyperemic conditions. Results on a patient with severe obstructive disease link coronary artery narrowing with impaired myocardial blood flow, demonstrating the model’s ability to predict myocardial regions with perfusion deficit. This is the first report of a computational model for simulating blood flow from the epicardial coronary arteries to the left ventricle myocardium applied to and validated on human data.

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.

METHODOLOGICAL ASPECTS OF VISUALIZATION OF CORONARY ARTERIES WITH TRANSTHORACIC ECHOCARDIOGRAPHY

2018 ◽  
pp. 26-35
Author(s):  
Z. A. Agaeva ◽  
K. B. Baghdasaryan
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Arteries ◽  
Transthoracic Echocardiography ◽  
Second Harmonic ◽  
Anatomic Reconstruction ◽  
High Quality ◽  
Acoustic Window ◽  
Methodological Aspects

The transthoracic echocardiography made by multifrequency probes with support of the mode of the second harmonic imaging, is a competitive method for visualization of the main coronary arteries and allows to estimate coronary blood flow with high quality. Of course, the method has considerable restrictions, most important of which is the low spatial resolution of a method, due to small acoustic window. Because of this the transthoracic visualization of coronary arteries perhaps will not become the leading method of anatomic reconstruction of separately taken coronary artery and especially all coronary arteries system. However uniqueness and indisputable advantage of this method is an opportunity to noninvasively estimate a coronary blood flow both once, and in dynamics.

scholarly journals Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042110080
Author(s):  
Zheqin Yu ◽  
Jianping Tan ◽  
Shuai Wang
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Multiphase Flow ◽  
Experimental Verification ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Phase Model ◽  
Force Model ◽  
Discrete Phase Model ◽  
Discrete Phase

Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

Sign in / Sign up

Export Citation Format

Share Document