scholarly journals Effects of size and elasticity on the relation between flow velocity and wall shear stress in side-wall aneurysms: A lattice Boltzmann-based computer simulation study

2019 ◽  
Author(s):  
Haifeng Wang ◽  
Timm Krüger ◽  
Fathollah Varnik
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Velocity ◽  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Side Wall ◽  
Aneurysm Rupture ◽  
Immersed Boundary ◽  
Wall Shear

AbstractBlood flow in an artery is a fluid-structure interaction problem. It is widely accepted that aneurysm formation, enlargement and failure are associated with wall shear stress (WSS) which is exerted by flowing blood on the aneurysmal wall. To date, the combined effect of aneurysm size and wall elasticity on intra-aneurysm (IA) flow characteristics, particularly in the case of side-wall aneurysms, is poorly understood. Here we propose a model of three-dimensional viscous flow in a compliant artery containing an aneurysm by employing the immersed boundary-lattice Boltzmann-finite element method. This model allows to adequately account for the elastic deformation of both the blood vessel and aneurysm walls. Using this model, we perform a detailed investigation of the flow through aneurysm under different conditions with a focus on the parameters which may influence the wall shear stress. Most importantly, it is shown in this work that the use of flow velocity as a proxy for wall shear stress is well justified only in those sections of the vessel which are close to the ideal cylindrical geometry. Within the aneurysm domain, however, the correlation between wall shear stress and flow velocity is largely lost due to the complexity of the geometry and the resulting flow pattern. Moreover, the correlations weaken further with the phase shift between flow velocity and transmural pressure. These findings have important implications for medical applications since wall shear stress is believed to play a crucial role in aneurysm rupture.

Lattice Boltzmann Simulation of Effect of Rolling Manipulation of Traditional Chinese Massage on Blood Flow

2013 ◽  
Vol 275-277 ◽  
pp. 472-477
Author(s):  
Hui Li Tan ◽  
Fan Rong Kong ◽  
Ke Zhao Bai ◽  
Ling Jiang Kong
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Velocity ◽  
Lattice Boltzmann ◽  
Lattice Boltzmann Model ◽  
Lattice Boltzmann Simulation ◽  
Simulation Based ◽  
Wall Shear ◽  
Boltzmann Method ◽  
Boltzmann Model

A 2D Lattice Boltzmann model for a blood vesssel under rolling manipulation(RM) was presented. The influence of rolling frequency and stenosis coefficient on blood flux, wall shear stress and flow velocity was given by the numerical simulation based on lattice Boltzmann method . It is found that increasing RM frequency can not always increase the flux. There is a proper RM frequency for maximum flux.When the maximum stenosis coefficient increases,the change range of flux and wall shear stress will increase. The rolling massage can also change flow velocity in different sections of blood vessel.

scholarly journals Bicuspid Aortic Cusp Fusion Morphology Alters Aortic Three-Dimensional Outflow Patterns, Wall Shear Stress, and Expression of Aortopathy

Circulation ◽  
2014 ◽  
Vol 129 (6) ◽  
pp. 673-682 ◽  
Author(s):  
Riti Mahadevia ◽  
Alex J. Barker ◽  
Susanne Schnell ◽  
Pegah Entezari ◽  
Preeti Kansal ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Three Dimensional ◽  
Aortic Cusp ◽  
Wall Shear

Changes in wall shear stress magnitude after aneurysm rupture

2013 ◽  
Vol 155 (8) ◽  
pp. 1559-1563 ◽  
Author(s):  
Kenichi Kono ◽  
Nagatsuki Tomura ◽  
Ryo Yoshimura ◽  
Tomoaki Terada
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Aneurysm Rupture ◽  
Wall Shear

Clinical, morphological, and hemodynamic independent characteristic factors for rupture of posterior communicating artery aneurysms

2015 ◽  
Vol 8 (8) ◽  
pp. 808-812 ◽  
Author(s):  
Ying Zhang ◽  
Linkai Jing ◽  
Jian Liu ◽  
Chuanhui Li ◽  
Jixing Fan ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Univariate Analysis ◽  
Multivariate Logistic Regression Analysis ◽  
Aneurysm Rupture ◽  
Irregular Shape ◽  
Posterior Communicating Artery ◽  
Patient Specific ◽  
Younger Age ◽  
Wall Shear

ObjectiveTo identify clinical, morphological, and hemodynamic independent characteristic factors that discriminate posterior communicating artery (PCoA) aneurysm rupture status.Methods173 patients with single PCoA aneurysms (108 ruptured, 65 unruptured) between January 2012 and June 2014 were retrospectively collected. Patient-specific models based on their three-dimensional digital subtraction angiography images were constructed and analyzed by a computational fluid dynamic method. All variables were analyzed by univariate analysis and multivariate logistic regression analysis.ResultsTwo clinical factors (younger age and atherosclerosis), three morphological factors (higher aspect ratio, bifurcation type, and irregular shape), and six hemodynamic factors (lower mean and minimum wall shear stress, higher oscillatory shear index, a greater portion of area under low wall shear stress, unstable and complex flow pattern) were significantly associated with PCoA aneurysm rupture. Independent factors characterizing the rupture status were identified as age (OR 0.956, p=0.015), irregular shape (OR 6.709, p<0.001), and minimum wall shear stress (OR 0.001, p=0.038).ConclusionsWe combined clinical, morphological, and hemodynamic characteristics analysis and found the three strongest independent factors for PCoA aneurysm rupture were younger age, irregular shape, and low minimum wall shear stress. This may be useful for guiding risk assessments and subsequent treatment decisions for PCoA aneurysms.

Inflammatory Response of Endothelial Cells to Wall Shear Stress in Three Dimensional Stenotic Models

2009 ◽  
Author(s):  
Leonie Rouleau ◽  
Joanna Rossi ◽  
Jean-Claude Tardif ◽  
Rosaire Mongrain ◽  
Richard L. Leask
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Three Dimensional ◽  
Realistic Model ◽  
In Vitro Models ◽  
Steady Flows ◽  
Wall Shear

Endothelial cells (ECs) are believed to respond differentially to hemodynamic forces in the vascular tree. Once atherosclerotic plaque has formed in a vessel, the obstruction creates complex spatial gradients in wall shear stress (WSS). In vitro models have used mostly unrealistic and simplified geometries, which cannot reproduce accurately physiological conditions. The objective of this study was to expose ECs to the complex WSS pattern created by an asymmetric stenosis. Endothelial cells were grown and exposed for different times to physiological steady flows in straight dynamic controls and in idealized asymmetric stenosis models. Cell morphology was noticeably different in the regions with spatial WSS gradients, being more randomly oriented and of cobblestone shape. Inflammatory molecule expression was also altered by exposure to shear and endothelial nitric oxide synthase (eNOS) was upregulated by its presence. A regional response in terms of inflammation was observed through confocal microscopy. This work provides a more realistic model to study endothelial cell response to spatial and temporal WSS gradients that are present in vivo and is an important advancement towards a better understanding of the mechanisms involved in coronary artery disease.

Entropy hemodynamics particle-fluid suspension model through eccentric catheterization for time-variant stenotic arterial wall: Catheter injection

2019 ◽  
Vol 16 (11) ◽  
pp. 1950164 ◽  
Author(s):  
Kh. S. Mekheimer ◽  
A. Z. Zaher ◽  
A. I. Abdellateef
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Temperature Distribution ◽  
Wall Shear Stress ◽  
Outer Cylinder ◽  
Flow Characteristics ◽  
Two Phase ◽  
Eccentric Cylinder ◽  
Wall Shear ◽  
Suspension Model

Catheterization has an imperative rule in heat transfer investigations, which are frequently applied to analyze and deal with the heart transfer studies. Here, the entering of a catheter adjusts the flow of the blood and it affects the hemodynamic status in the artery region. In practical clinical cases, catheters cannot be precisely concentric with the artery. The impartial of this work is to investigate the behavior of a blood streaming characteristics, in the case of injecting the catheter eccentrically all the way through a stenotic overlapping artery. In this paper, we consider the heat transfer within the presence of blood corpuscle which has been characterized by a macroscopic two-phase model (i.e. a suspension of erythrocytes in plasma). The model here considers the blood fluid as a liquid fluid with adjourned particles in the gap bounded by the eccentric cylinder. The inside cylinder is identically rigid demonstrating the movable thin catheter and kept at constant temperature, where the outer cylinder is a taper cylinder demonstrating the artery that has overlapping stenosis and it is cooled and maintained at zero temperature. The coupled differential equations for both fluid (plasma) and particle (erythrocyte) phases have been solved. The expressions for the flow characteristics, namely, the flow rate, the impedance (resistance to flow), the wall shear stress and the temperature distribution, have been derived. The model is very useful in medicine, where the hemodynamic speed is higher for eccentric case than that of concentric one. Also, the temperature distribution and the entropy generation in the state of eccentric position are higher than in the case of the concentric position. A significant increase in the magnitude of the impedance and the wall shear stress occurs for an increase in the hematocrit, C for diseased blood.

Three-dimensional vortical structures and wall shear stress in a curved artery model

2019 ◽  
Vol 31 (12) ◽  
pp. 121903 ◽  
Author(s):  
Christopher Cox ◽  
Mohammad Reza Najjari ◽  
Michael W. Plesniak
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Three Dimensional ◽  
Vortical Structures ◽  
Curved Artery ◽  
Wall Shear
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