scholarly journals Wall Shear Stress Topological Skeleton Analysis in Cardiovascular Flows: Methods and Applications

Mathematics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 720
Author(s):  
Valentina Mazzi ◽  
Umberto Morbiducci ◽  
Karol Calò ◽  
Giuseppe De Nisco ◽  
Maurizio Lodi Rizzini ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Fixed Points ◽  
Vascular Diseases ◽  
Dynamical System Theory ◽  
Focal Points ◽  
Clinical Observations ◽  
Flow Disturbances ◽  
Wall Shear ◽  
Processing Techniques

A marked interest has recently emerged regarding the analysis of the wall shear stress (WSS) vector field topological skeleton in cardiovascular flows. Based on dynamical system theory, the WSS topological skeleton is composed of fixed points, i.e., focal points where WSS locally vanishes, and unstable/stable manifolds, consisting of contraction/expansion regions linking fixed points. Such an interest arises from its ability to reflect the presence of near-wall hemodynamic features associated with the onset and progression of vascular diseases. Over the years, Lagrangian-based and Eulerian-based post-processing techniques have been proposed aiming at identifying the topological skeleton features of the WSS. Here, the theoretical and methodological bases supporting the Lagrangian- and Eulerian-based methods currently used in the literature are reported and discussed, highlighting their application to cardiovascular flows. The final aim is to promote the use of WSS topological skeleton analysis in hemodynamic applications and to encourage its application in future mechanobiology studies in order to increase the chance of elucidating the mechanistic links between blood flow disturbances, vascular disease, and clinical observations.

A Eulerian method to analyze wall shear stress fixed points and manifolds in cardiovascular flows

2019 ◽  
Vol 19 (5) ◽  
pp. 1403-1423 ◽  
Author(s):  
Valentina Mazzi ◽  
Diego Gallo ◽  
Karol Calò ◽  
Mehdi Najafi ◽  
Muhammad Owais Khan ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Fixed Points ◽  
Eulerian Method ◽  
Wall Shear

scholarly journals Mis-sizing of stent promotes intimal hyperplasia: impact of endothelial shear and intramural stress

2011 ◽  
Vol 301 (6) ◽  
pp. H2254-H2263 ◽  
Author(s):  
Henry Y. Chen ◽  
Anjan K. Sinha ◽  
Jenny S. Choy ◽  
Hai Zheng ◽  
Michael Sturek ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Coronary Arteries ◽  
Vessel Wall ◽  
Solid Mechanics ◽  
Linear Regression Analysis ◽  
Wall Stress ◽  
Linear Relations ◽  
Flow Disturbances ◽  
Wall Shear

Stent can cause flow disturbances on the endothelium and compliance mismatch and increased stress on the vessel wall. These effects can cause low wall shear stress (WSS), high wall shear stress gradient (WSSG), oscillatory shear index (OSI), and circumferential wall stress (CWS), which may promote neointimal hyperplasia (IH). The hypothesis is that stent-induced abnormal fluid and solid mechanics contribute to IH. To vary the range of WSS, WSSG, OSI, and CWS, we intentionally mismatched the size of stents to that of the vessel lumen. Stents were implanted in coronary arteries of 10 swine. Intravascular ultrasound (IVUS) was used to size the coronary arteries and stents. After 4 wk of stent implantation, IVUS was performed again to determine the extent of IH. In conjunction, computational models of actual stents, the artery, and non-Newtonian blood were created in a computer simulation to yield the distribution of WSS, WSSG, OSI, and CWS in the stented vessel wall. An inverse relation ( R2 = 0.59, P < 0.005) between WSS and IH was found based on a linear regression analysis. Linear relations between WSSG, OSI, and IH were observed ( R2 = 0.48 and 0.50, respectively, P < 0.005). A linear relation ( R2 = 0.58, P < 0.005) between CWS and IH was also found. More statistically significant linear relations between the ratio of CWS to WSS (CWS/WSS), the products CWS × WSSG and CWS × OSI, and IH were observed ( R2 = 0.67, 0.54, and 0.56, respectively, P < 0.005), suggesting that both fluid and solid mechanics influence the extent of IH. Stents create endothelial flow disturbances and intramural wall stress concentrations, which correlate with the extent of IH formation, and these effects were exaggerated with mismatch of stent/vessel size. These findings reveal the importance of reliable vessel and stent sizing to improve the mechanics on the vessel wall and minimize IH.

Influence of Intermittent Pneumatic Compression on Wall Shear Stress and Nitric Oxide Levels

2011 ◽  
Author(s):  
Ganesh Swaminathan ◽  
Suraj Thyagaraj ◽  
Francis Loth ◽  
Susan McCormick ◽  
Hisham Bassiouny
Keyword(s):  
Nitric Oxide ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Blood Vessels ◽  
Healthy Subjects ◽  
Vascular Diseases ◽  
Intermittent Pneumatic Compression ◽  
Peripheral Vascular ◽  
Peripheral Vascular Diseases ◽  
Wall Shear

Wall shear stress (WSS) in blood vessels has been shown to play an important role in the development of atherosclerosis. In particular, regions of low and oscillating WSS have been shown to correlate with the localization of atherosclerosis. Thus, we hypothesize that increasing the WSS for patients with peripheral vascular diseases (PVD) will either reduce PVD severity or slow its progression. We analyzed WSS changes from a study by Delis et al. on 32 limbs of PVD patients [1]. Results show that intermittent pneumatic compression (IPC) increases mean WSS by 170% and 240% in PVD patients and healthy subjects, respectively. Peak WSS was found to increase by 93% and 40% in PVD patients and healthy subjects, respectively. In addition, we examined changes in NOX level with use of IPC on five limbs from PVD patients. Our study demonstrated increased NOx levels in subjects after IPC. Further research is needed to determine the benefits of IPC for PVD patients.

Effect of Wall Shear Stress on Abdominal Aortic Aneurysm Expansion: Study With Longitudinal Patient Images

2012 ◽  
Author(s):  
B. Zambrano ◽  
A. Dupay ◽  
F. Jaberi ◽  
W. Lee ◽  
S. Baek
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Open Surgery ◽  
Vascular Diseases ◽  
Aortic Aneurysms ◽  
Maximum Diameter ◽  
Abdominal Aortic ◽  
Reduce Risk ◽  
Wall Shear

Abdominal Aortic Aneurysms (AAA), a focal enlargement of abdominal aorta, is a form of vascular diseases that affects large part of the population. It can cause the mortality up to 90% of the cases when it ruptures. Currently, the best known treatment to reduce risk is open surgery or endovascular repair. Since the risk of such surgery repair is high, in most patients with AAAs< 55mm in its maximum diameter the surgical treatment is postponed. An effort to enhance the accuracy of the risk assessment and to prevent AAA’s growth and rupture is being made, but the mechanisms promoting AAAs growth are still largely unknown. AAAs can be affected by different factors, among those, hemodynamics is known to play important roles in AAA initiation and progression. Particularly, the wall shear stress is believed to contribute to AAA expansion and rupture. For the present study, we use geometries constructed from longitudinal CT images obtained during AAA follow-up studies and investigate relations between multiple hemodynamics factors with local expansion of AAAs.

scholarly journals Fluid-structure interaction simulation of tissue degradation and its effects on intra-aneurysm hemodynamics

2022 ◽  
Author(s):  
Haifeng Wang ◽  
Klemens Uhlmann ◽  
Vijay Vedula ◽  
Daniel Balzani ◽  
Fathollah Varnik
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Vascular Diseases ◽  
Von Mises Stress ◽  
Arterial Walls ◽  
Tissue Degradation ◽  
Blood Pressures ◽  
Arterial Wall Mechanics ◽  
Wall Shear ◽  
Von Mises

AbstractTissue degradation plays a crucial role in vascular diseases such as atherosclerosis and aneurysms. Computational modeling of vascular hemodynamics incorporating both arterial wall mechanics and tissue degradation has been a challenging task. In this study, we propose a novel finite element method-based approach to model the microscopic degradation of arterial walls and its interaction with blood flow. The model is applied to study the combined effects of pulsatile flow and tissue degradation on the deformation and intra-aneurysm hemodynamics. Our computational analysis reveals that tissue degradation leads to a weakening of the aneurysmal wall, which manifests itself in a larger deformation and a smaller von Mises stress. Moreover, simulation results for different heart rates, blood pressures and aneurysm geometries indicate consistently that, upon tissue degradation, wall shear stress increases near the flow-impingement region and decreases away from it. These findings are discussed in the context of recent reports regarding the role of both high and low wall shear stress for the progression and rupture of aneurysms.

Coronary Artery Stenting Affects Wall Shear Stress Topological Skeleton

2022 ◽  
Author(s):  
Claudio Chiastra ◽  
Valentina Mazzi ◽  
Maurizio Lodi Rizzini ◽  
Karol Calò ◽  
Anna Corti ◽  
...  
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Vascular Diseases ◽  
Human Coronary Artery ◽  
Term Outcome ◽  
Clinical Images ◽  
Long Term Outcome ◽  
Wall Shear ◽  
The Impact

Abstract Despite the important advancements in the stent technology for the treatment of diseased coronary arteries, major complications still affect the post-operative long-term outcome. The stent-induced flow disturbances, and especially the altered wall shear stress (WSS) profile at the strut level, play an important role in the pathophysiological mechanisms leading to stent thrombosis (ST) and in-stent restenosis (ISR). In this context, the analysis of the WSS topological skeleton is gaining more and more interest by extending the current understanding of the association between local hemodynamics and vascular diseases. The present study aims to analyze the impact that a deployed coronary stent has on the WSS topological skeleton. Computational fluid dynamics simulations were performed in three stented human coronary artery geometries reconstructed from clinical images. The selected cases presented stents with different designs (i.e., two contemporary drug eluting stents and one bioresorbable scaffold) and included regions with stent malapposition or overlapping. A recently proposed Eulerian-based approach was applied to analyze the WSS topological skeleton features. The results highlighted that the presence of single or multiple stents within a coronary artery markedly impacts the WSS topological skeleton. In particular, repetitive patterns of WSS divergence were observed at the luminal surface, highlighting a WSS contraction action proximal to the struts and a WSS expansion action distal to the struts. This WSS action pattern was independent from the stent design. In conclusions, these findings could contribute to a deeper understanding of the hemodynamic-driven processes underlying ST and ISR.

scholarly journals Fluid-structure interaction simulation of tissue degradation and its effects on intra-aneurysm hemodynamics

2021 ◽  
Author(s):  
Haifeng Wang ◽  
Klemens Uhlmann ◽  
Vijay Vedula ◽  
Daniel Balzani ◽  
Fathollah Varnik
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Vascular Diseases ◽  
Von Mises Stress ◽  
Aneurysmal Wall ◽  
Tissue Degradation ◽  
Blood Pressures ◽  
Interaction Simulation ◽  
Wall Shear ◽  
Von Mises

Tissue degradation plays a crucial role in vascular diseases such as atherosclerosis and aneurysms. We present a novel finite element method-based approach to model the microscopic degradation of an aneurysmal wall due to its interaction with blood flow. The model is applied to study the combined effects of pulsatile flow and tissue degradation on the deformation and intra-aneurysm hemodynamics. Our computational analysis reveals that tissue degradation leads to a weakening of the aneurysmal wall, which manifests itself in a larger deformation and a smaller von Mises stress. Moreover, simulation results for different heart rates, blood pressures and aneurysm geometries indicate consistently that, upon tissue degradation, wall shear stress increases near the flow-impingement region and decreases away from it. These findings are discussed in the context of recent reports regarding the role of both high and low wall shear stress for the progression and rupture of aneurysms.

Relating Wall Shear Stress, Bleb Formation and Rupture of Cerebral Aneurysms: Image-Based Modeling and Clinical Observations

2008 ◽  
Author(s):  
Juan R. Cebral ◽  
Christopher M. Putman
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Computational Models ◽  
Cerebral Aneurysms ◽  
Clinical Observations ◽  
History Of ◽  
Wall Shear ◽  
Blood Flow Patterns

Cerebral aneurysms are widely believed to form and grow as a result of the interactions of hemodynamics and wall mechano-biology. Researchers have used a variety of tools to study these complex multi-factorial mechanisms including animal, in vitro, and computational models. The goal of these experiments has been to approximate the in vivo environment so that theories about the natural history of brain aneurysms can be developed and tested in realistic systems. Studying the link between hemodynamics and clinical observations of aneurysm progression is necessary to reach an understanding of the relative importance of the different mechanisms involved in these processes [1]. The objective of our research is to investigate the possible relationship between wall shear stress (WSS) — which is known to regulate mechano-biological processes at the arterial wall — produced by different blood flow patterns and the evolution and rupture of cerebral aneurysms.

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