Effects of Cyclic Motion on Coronary Blood Flow

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Mahmudul Hasan ◽  
David A. Rubenstein ◽  
Wei Yin
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Blood Vessel ◽  
Coronary Blood Flow ◽  
Vessel Wall ◽  
Wall Stress ◽  
Blood Vessel Wall ◽  
Flow Parameters ◽  
Cyclic Motion

The goal of this study was to establish a computational fluid dynamics model to investigate the effect of cyclic motion (i.e., bending and stretching) on coronary blood flow. The three-dimensional (3D) geometry of a 50-mm section of the left anterior descending artery (normal or with a 60% stenosis) was constructed based on anatomical studies. To describe the bending motion of the blood vessel wall, arbitrary Lagrangian–Eularian methods were used. To simulate artery bending and blood pressure change induced stretching, the arterial wall was modeled as an anisotropic nonlinear elastic solid using the five-parameter Mooney–Rivlin hyperelastic model. Employing a laminar model, the flow field was solved using the continuity equations and Navier–Stokes equations. Blood was modeled as an incompressible Newtonian fluid. A fluid–structure interaction approach was used to couple the fluid domain and the solid domain iteratively, allowing force and total mesh displacement to be transferred between the two domains. The results demonstrated that even though the bending motion of the coronary artery could significantly affect blood cell trajectory, it had little effect on flow parameters, i.e., blood flow velocity, blood shear stress, and wall shear stress. The shape of the stenosis (asymmetric or symmetric) hardly affected flow parameters either. However, wall normal stresses (axial, circumferential, and radial stress) can be greatly affected by the blood vessel wall motion. The axial wall stress was significantly higher than the circumferential and radial stresses, as well as wall shear stress. Therefore, investigation on effects of wall stress on blood vessel wall cellular functions may help us better understand the mechanism of mechanical stress induced cardiovascular disease.

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.

A Numerical Multiscale Study of the Haemodynamics in an Image-Based Model of Human Carotid Artery Bifurcation

2009 ◽  
Author(s):  
Diego Gallo ◽  
Raffaele Ponzini ◽  
Filippo Consolo ◽  
Diana Massai ◽  
Luca Antiga ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Cardiovascular System ◽  
Vessel Wall ◽  
3D Model ◽  
Carotid Bifurcation ◽  
Wall Shear ◽  
Flow Division

The initiation and progression of vessel wall pathologies have been linked to disturbances of blood flow and altered wall shear stress. The development of computational techniques in fluid dynamics, together with the increasing performances of hardware and software allow to routinely solve problems on a virtual environment, helping to understand the role of biomechanics factors in the healthy and diseased cardiovascular system and to reveal the interplay of biology and local fluid dynamics nearly intractable in the past, opening to detailed investigation of parameters affecting disease progression. One of the major difficulties encountered when wishing to model accurately the cardiovascular system is that the flow dynamics of the blood in a specific vascular district is strictly related to the global systemic dynamics. The multiscale modelling approach for the description of blood flow into vessels consists in coupling a detailed model of the district of interest in the framework of a synthetic description of the surrounding areas of the vascular net [1]. In the present work, we aim at evaluating the effect of boundary conditions on wall shear stress (WSS) related vessel wall indexes and on bulk flow topology inside a carotid bifurcation. To do it, we coupled an image-based 3D model of carotid bifurcation (local computational domain), with a lumped parameters (0D) model (global domain) which allows for physiological mimicking of the haemodynamics at the boundaries of the 3D carotid bifurcation model here investigated. Two WSS based blood-vessel wall interaction descriptors, the Time Averaged WSS (TAWSS), and the Oscillating Shear Index (OSI) were considered. A specific Lagrangian-based “bulk” blood flow descriptor, the Helical Flow Index (HFI) [2], was calculated in order to get a “measure” of the helical structure in the blood flow. In a first analysis the effects of the coupled 0D models on the 3D model are evaluated. The results obtained from the multiscale simulation are compared with the results of simulations performed using the same 3D model, but imposing a flow rate at internal carotid (ICA) outlet section equal to the maximum (60%) and the minimum (50%) flow division obtained out from ICA in the multiscale model simulation (the presence of the coupled 0D model gives variable internal/external flow division ratio during the cardiac cycle), and a stress free condition on the external carotid (ECA).

Coupling Vibration Analysis of Blood Vessels

2001 ◽  
Author(s):  
Jingliang Miao ◽  
Haixiang Liu
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Blood Vessels ◽  
Dynamic Model ◽  
Natural Frequency ◽  
Vibration Analysis ◽  
Vessel Wall ◽  
Blood Vessel Wall ◽  
Coupled Vibration ◽  
Coupling Vibration

Abstract This paper proposes and analyzes a simple dynamic model of blood vessel wall. By studying the coupled vibration of blood flow and vessel wall, one can get the natural frequency of a blood vessel. The method used here is generalized calculus of variations. The results show that the flexibility of blood vessels has a greater influence on the fundamental frequency of the coupled vibration and the viscosity of blood vessel has little effect on the frequency of the coupled vibration but has a greater effect on the amplitude of the vibration. Therefore it is important to control both the viscosity and flexibility of blood vessels.

scholarly journals Shear stress and aneurysms: a review

2019 ◽  
Vol 47 (1) ◽  
pp. E2 ◽  
Author(s):  
Brittany Staarmann ◽  
Matthew Smith ◽  
Charles J. Prestigiacomo
Keyword(s):  
Endothelial Cells ◽  
Blood Flow ◽  
Shear Stress ◽  
Smooth Muscle ◽  
Wall Shear Stress ◽  
Smooth Muscle Cells ◽  
Frictional Force ◽  
Vessel Wall ◽  
Risk Of Rupture ◽  
Aneurysm Growth

Wall shear stress, the frictional force of blood flow tangential to an artery lumen, has been demonstrated in multiple studies to influence aneurysm formation and risk of rupture. In this article, the authors review the ways in which shear stress may influence aneurysm growth and rupture through changes in the vessel wall endothelial cells, smooth-muscle cells, and surrounding adventitia, and they discuss shear stress–induced pathways through which these changes occur.

scholarly journals INFLUENCE OF AGE AND GENDER ON THE STRENGTH OF BLOOD VESSELS

2016 ◽  
Vol 4 ◽  
pp. 719-726
Author(s):  
Zyta Kuzborska
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Flow Velocity ◽  
Blood Vessels ◽  
Blood Flow Velocity ◽  
Vessel Wall ◽  
Blood Vessel Wall ◽  
Critical Stresses ◽  
And Gender

This article examines the effects of cardiovascular diseases that alter the diameter, wall thickness, and length of blood vessels. Depending on form and size of the damage, blood flow velocity, blood pressure, and stresses are affected in areas of diseased blood vessels. Through stimulating the deviations in the geometric shape of a blood-vessel wall, local blood pressure and stresses can arise from flow variation of blood vessels. This rise affects the blood-vessel wall and causes critical stresses likely to produce fissures in the blood vessels. It was found, that blood vessel pathology could cause blood flow velocity to increase up to 2.2 times and local blood pressure up to 3.4 times, and that human aging may have a significant influence on blood-vessel strength.

Large Eddy Simulation of Flow Through a Stenosed Pipe

2008 ◽  
Author(s):  
Roland Gårdhagen ◽  
Jonas Lantz ◽  
Fredrik Carlsson ◽  
Matts Karlsson
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Vessel Wall ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Through ◽  
Disease Initiation ◽  
Developed World ◽  
Intense Research

A majority of all deaths in the developed world are related to atherosclerosis, i.e. obstruction of blood vessels caused by growth of the vessel wall. Hemodynamic phenomena, especially wall shear stress, are since several decades thought to influence the risk to develop atherosclerosis; hence simulation of blood flow, either in order to elucidate the relation between the hemodynamic and disease initiation or to study the flow pattern, is an area of intense research [1,2].

scholarly journals Focal irregularities in 7-Tesla MRI of unruptured intracranial aneurysms as an indicator for areas of altered blood-flow parameters

2019 ◽  
Vol 47 (6) ◽  
pp. E7
Author(s):  
Matthias Millesi ◽  
Engelbert Knosp ◽  
Georg Mach ◽  
Johannes A. Hainfellner ◽  
Gerda Ricken ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Field Strength ◽  
Vessel Wall ◽  
Intracranial Aneurysms ◽  
7 Tesla ◽  
Risk Of Rupture ◽  
Wall Shear ◽  
Cfd Analyses

OBJECTIVEIn the last several decades, various factors have been studied for a better evaluation of the risk of rupture in incidentally discovered intracranial aneurysms (IAs). With advanced MRI, attempts were made to delineate the wall of IAs to identify weak areas prone to rupture. However, the field strength of the MRI investigations was insufficient for reasonable image resolution in many of these studies. Therefore, the aim of this study was to analyze findings of IAs in ultra–high field MRI at 7 Tesla (7 T).METHODSPatients with incidentally found IAs of at least 5 mm in diameter were included in this study and underwent MRI investigations at 7 T. At this field strength a hyperintense intravascular signal can be observed on nonenhanced images with a brighter “rim effect” along the vessel wall. Properties of this rim effect were evaluated and compared with computational fluid dynamics (CFD) analyses.RESULTSOverall, 23 aneurysms showed sufficient image quality for further evaluation. In 22 aneurysms focal irregularities were identified within this rim effect. Areas of such irregularities showed significantly higher values in wall shear stress and vorticity compared to areas with a clearly visible rim effect (p = 0.043 in both).CONCLUSIONSA hyperintense rim effect along the vessel wall was observed in most cases. Focal irregularities within this rim effect showed higher values of the mean wall shear stress and vorticity when compared by CFD analyses. Therefore, these findings indicate alterations in blood flow in IAs within these areas.

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