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).

Computational Fluid Dynamics of a Vascular Access Case for Hemodialysis

2000 ◽  
Vol 123 (3) ◽  
pp. 284-292 ◽  
Author(s):  
Bogdan Ene-Iordache ◽  
Lidia Mosconi ◽  
Giuseppe Remuzzi ◽  
Andrea Remuzzi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Radial Artery ◽  
Stress Gradient ◽  
Vascular Lesions ◽  
Patient Specific ◽  
Wall Shear

Vascular accesses (VA) for hemodialysis are usually created by native arteriovenous fistulas (AVF) or synthetic grafts. Maintaining patency of VA continues to be a major problem for patients with end-stage renal disease, since in these vessels thrombosis and intimal hyperplasia often occur. These lesions are frequently associated with disturbed flow that develops near bifurcations or sharp curvatures. We explored the possibility of investigating blood flow dynamics in a patient-specific model of end-to-end native AVF using computational fluid dynamics (CFD). Using digital subtraction angiographies of an AVF, we generated a three-dimensional meshwork for numerical analysis of blood flow. As input condition, a time-dependent blood waveform in the radial artery was derived from centerline velocity obtained during echo-color-Doppler ultrasound examination. The finite element solution was calculated using a fluid-dynamic software package. In the straight, afferent side of the radial artery wall shear stress ranged between 20 and 36 dynes/cm2, while on the inner surface of the bending zone it increased up to 350 dynes/cm2. On the venous side, proximal to the anastomosis, wall shear stress was oscillating between negative and positive values (from −12 dynes/cm2 to 112 dynes/cm2), while distal from the anastomosis, the wall shear stress returned within the physiologic range, ranging from 8 to 22 dynes/cm2. Areas of the vessel wall with very high shear stress gradient were identified on the bending zone of the radial artery and on the venous side, after the arteriovenous shunt. Secondary blood flows were also observed in these regions. CFD gave a detailed description of blood flow field and showed that this approach can be used for patient-specific analysis of blood vessels, to understand better the role of local hemodynamic conditions in the development of vascular lesions.

Sensitivity of Hemodynamic Parameters to Waveform, Flow Division, and Head Rotation in the Human Carotid Bifurcation

2008 ◽  
Author(s):  
Yannis Papaharilaou ◽  
Ioannis Seimenis ◽  
John Ekaterinaris ◽  
Georgios Georgiou ◽  
Eleni Eracleous ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Head Rotation ◽  
Carotid Bifurcation ◽  
Hemodynamic Parameters ◽  
Flow Waveform ◽  
Temporal Gradient ◽  
Wall Shear ◽  
Flow Division ◽  
Human Carotid

Hemodynamic parameters such as time averaged wall shear stress (TAWSS), wall shear stress temporal gradient (WSSTG) and Oscillatory Shear Index (OSI) have previously been cited as parameters associated with the development of atherosclerotic disease at the human carotid bifurcation [1,2]. The sensitivity of these important parameters however, with variations of driving flow waveform, flow division and posture changes are not well known. To investigate these changes, we have used image based CFD, to analyze the flowfield of the carotid bifurcation of a healthy volunteer for five different input waveforms, three flow division ratios and two head postures.

scholarly journals Spatial correlations between MRI-derived wall shear stress and vessel wall thickness in the carotid bifurcation

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Pim van Ooij ◽  
Merih Cibis ◽  
Ethan M. Rowland ◽  
Meike W. Vernooij ◽  
Aad van der Lugt ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Wall Thickness ◽  
Vessel Wall ◽  
Carotid Bifurcation ◽  
Spatial Correlations ◽  
Vessel Wall Thickness ◽  
Wall Shear

scholarly journals ESTIMATION OF WALL SHEAR STRESS USING 4D FLOW CARDIOVASCULAR MRI AND COMPUTATIONAL FLUID DYNAMICS

2016 ◽  
Vol 17 (03) ◽  
pp. 1750046 ◽  
Author(s):  
E. SOUDAH ◽  
J. CASACUBERTA ◽  
P. J. GAMEZ-MONTERO ◽  
J. S. PÉREZ ◽  
M. RODRÍGUEZ-CANCIO ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Cardiovascular Magnetic Resonance ◽  
Magnetic Resonance ◽  
Wall Shear Stress ◽  
Thoracic Aorta ◽  
4D Flow ◽  
Wall Shear

In the last few years, wall shear stress (WSS) has arisen as a new diagnostic indicator in patients with arterial disease. There is a substantial evidence that the WSS plays a significant role, together with hemodynamic indicators, in initiation and progression of the vascular diseases. Estimation of WSS values, therefore, may be of clinical significance and the methods employed for its measurement are crucial for clinical community. Recently, four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) has been widely used in a number of applications for visualization and quantification of blood flow, and although the sensitivity to blood flow measurement has increased, it is not yet able to provide an accurate three-dimensional (3D) WSS distribution. The aim of this work is to evaluate the aortic blood flow features and the associated WSS by the combination of 4D flow cardiovascular magnetic resonance (4D CMR) and computational fluid dynamics technique. In particular, in this work, we used the 4D CMR to obtain the spatial domain and the boundary conditions needed to estimate the WSS within the entire thoracic aorta using computational fluid dynamics. Similar WSS distributions were found for cases simulated. A sensitivity analysis was done to check the accuracy of the method. 4D CMR begins to be a reliable tool to estimate the WSS within the entire thoracic aorta using computational fluid dynamics. The combination of both techniques may provide the ideal tool to help tackle these and other problems related to wall shear estimation.

scholarly journals 4-D Computational Modeling of Cardiac Outflow Tract Hemodynamics over Looping Developmental Stages in Chicken Embryos

2019 ◽  
Vol 6 (1) ◽  
pp. 11 ◽  
Author(s):  
Katherine Courchaine ◽  
MacKenzie Gray ◽  
Kaitlin Beel ◽  
Kent Thornburg ◽  
Sandra Rugonyi
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Cardiovascular System ◽  
Heart Development ◽  
Morphological Changes ◽  
Tangential Force ◽  
Outflow Tract ◽  
Structural Development ◽  
Wall Shear

Cardiogenesis is interdependent with blood flow within the embryonic system. Recently, a number of studies have begun to elucidate the effects of hemodynamic forces acting upon and within cells as the cardiovascular system begins to develop. Changes in flow are picked up by mechanosensors in endocardial cells exposed to wall shear stress (the tangential force exerted by blood flow) and by myocardial and mesenchymal cells exposed to cyclic strain (deformation). Mechanosensors stimulate a variety of mechanotransduction pathways which elicit functional cellular responses in order to coordinate the structural development of the heart and cardiovascular system. The looping stages of heart development are critical to normal cardiac morphogenesis and have previously been shown to be extremely sensitive to experimental perturbations in flow, with transient exposure to altered flow dynamics causing severe late stage cardiac defects in animal models. This paper seeks to expand on past research and to begin establishing a detailed baseline for normal hemodynamic conditions in the chick outflow tract during these critical looping stages. Specifically, we will use 4-D (3-D over time) optical coherence tomography to create in vivo geometries for computational fluid dynamics simulations of the cardiac cycle, enabling us to study in great detail 4-D velocity patterns and heterogeneous wall shear stress distributions on the outflow tract endocardium. This information will be useful in determining the normal variation of hemodynamic patterns as well as in mapping hemodynamics to developmental processes such as morphological changes and signaling events during and after the looping stages examined here.

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.

scholarly journals Stent implantation alters coronary artery hemodynamics and wall shear stress during maximal vasodilation

2002 ◽  
Vol 93 (6) ◽  
pp. 1939-1946 ◽  
Author(s):  
John F. LaDisa ◽  
Douglas A. Hettrick ◽  
Lars E. Olson ◽  
Ismail Guler ◽  
Eric R. Gross ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Vascular Resistance ◽  
Stent Implantation ◽  
Oscillatory Shear ◽  
Wall Shear ◽  
Oscillatory Shear Stress

Coronary stents improve resting blood flow and flow reserve in the presence of stenoses, but the impact of these devices on fluid dynamics during profound vasodilation is largely unknown. We tested the hypothesis that stent implantation affects adenosine-induced alterations in coronary hemodynamics and wall shear stress in anesthetized dogs ( n = 6) instrumented for measurement of left anterior descending coronary artery (LAD) blood flow, velocity, diameter, and radius of curvature. Indexes of fluid dynamics and shear stress were determined before and after placement of a slotted-tube stent in the absence and presence of an adenosine infusion (1.0 mg/min). Adenosine increased blood flow, Reynolds (Re) and Dean numbers (De), and regional and oscillatory shear stress concomitant with reductions in LAD vascular resistance and segmental compliance before stent implantation. Increases in LAD blood flow, Re, De, and indexes of shear stress were observed after stent deployment ( P < 0.05). Stent implantation reduced LAD segmental compliance to zero and potentiated increases in segmental and coronary vascular resistance during adenosine. Adenosine-induced increases in coronary blood flow and reserve, Re, De, and regional and oscillatory shear stress were attenuated after the stent was implanted. The results indicate that stent implantation blunts alterations in fluid dynamics during coronary vasodilation in vivo.

scholarly journals The Hemodynamics of Aneurysms Treated with Flow-Diverting Stents Considering both Stent and Aneurysm/Artery Geometries

2020 ◽  
Vol 10 (15) ◽  
pp. 5239
Author(s):  
Paulo R. Cillo-Velasco ◽  
Rafaello D. Luciano ◽  
Michael E. Kelly ◽  
Lissa Peeling ◽  
Donald J. Bergstrom ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Hemodynamic Parameters ◽  
Stent Deployment ◽  
Flow Velocity Field ◽  
Relative Residence Time ◽  
Wall Shear

Flow diverting stents are deployed to reduce the blood flow into the aneurysm, which would thereby induce thrombosis in the aneurysm sac; the stents prevent its rupture. The present study aimed to examine and quantify the impacts of different flow stents on idealized configurations of the cerebral artery. In our study, we considered a spherical sidewall aneurysm located on curved and tortuous idealized artery vessels and three stents with different porosities (70, 80 and 90%) for deployment. Using computational fluid dynamics, the local hemodynamics in the presence and absence of the stents were simulated, respectively, under the assumption that the blood flow was unsteady and non-Newtonian. The hemodynamic parameters, such as the intra-aneurysmal flow, velocity field and wall shear stress and its related indices, were examined and compared among the 12 cases simulated. The results illustrated that with the stent deployment, the intra-aneurysmal flow and the wall shear stress and its related indices were considerably modified depending on both stent and aneurysm/artery geometries, and that the intra-aneurysmal relative residence time increased rapidly with decreasing stent porosity in all the vessel configurations. These results also inform the rationale for selecting stents for treating aneurysms of different configurations.

Response of Arteries to Near-Wall Fluid Dynamic Behavior

1990 ◽  
Vol 43 (5S) ◽  
pp. S98-S102 ◽  
Author(s):  
D. P. Giddens ◽  
C. K. Zarins ◽  
S. Glagov
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Smooth Muscle ◽  
Wall Shear Stress ◽  
Fluid Dynamic ◽  
Intimal Thickening ◽  
Long Term Changes ◽  
Wall Shear

Arteries are living tissues which react and adapt to their environment, particularly in relation to changes in the rate of blood flow required to supply peripheral tissues or organs. Medium and small size arteries increase in diameter in response to short-term demands for increased flow and decrease in diameter in the event of diminished demands. Such immediate reactions are regulated primarily by vasoactive substances acting directly on smooth muscle cells of the media or by release of smooth muscle relaxation or contraction factors elaborated by endothelial cells. Chronic or long-term changes in arterial diameter appear to be governed directly by near-wall flow phenomena, e.g. the fluid dynamic wall shear. Recent evidence suggests that the normal tendency of arteries to respond to long-term changes in the shear field can result in intimal thickening and that this response may also favor the development of atherosclerosis. Thus, there appears to be a close relationship between fluid dynamics and the structure of arteries. From the fluid dynamics viewpoint, the pulsatile, three dimensional nature of blood flow requires sophisticated experimental methods in order to provide adequate data for correlation with biological studies. Research within the past decade has led to the conclusion that arteries seek a vessel diameter-blood flow combination which results in a flow-induced mean wall shear stress of approximately 15 dynes/sq.cm. If this value is chronically exceeded, vessel enlargement develops. If normal baseline shear stress is not restored by this increase in radius, the local response may continue. Conversely, reduced wall shear tends to induce intimal thickening in order to reduce lumen radius and thus increase wall shear toward normal levels. Under certain conditions this reaction may progress to the development of atherosclerotic plaques. Despite this knowledge, key points remain to be clarified. Is it the wall shear stress or the wall shear rate which determines the reaction? The former possibility implies that a mechanical shear-related stimulus is at the heart of the biological response mechanisms while the latter suggests a mass transport-related mechanism.

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