Three Dimensional Numerical Analysis of Flow Through the Human Carotid Bifurcation With Varying Degrees of Stenotic Plaque Formation

2007 ◽  
Author(s):  
Scott T. Lovald ◽  
Tariq Khraishi ◽  
Juan C. Heinrich ◽  
Howard Yonas ◽  
Christopher L. Taylor
Keyword(s):  
Numerical Analysis ◽  
Carotid Artery ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
Local Flow ◽  
Flow Through ◽  
High Degree ◽  
The Brain ◽  
Insight Into ◽  
Human Carotid

The human carotid artery bifurcation is often affected by plaque and atherosclerotic formations. A high degree of stenosis due to plaque deposit in the carotid artery can significantly diminish blood flow to the brain [1]. For three decades, local flow anomalies such as flow separation, recirculation, low wall shear stress, and high local particle residence time are factors that have been implicated in the development of arterial diseases [3, 1]. Numerical analysis of flow through a stenotic carotid bifurcation provides insight into local flow dynamics and an assessment of the risks of particular modes and degrees of stenosis.

In Vitro Three Dimensional Imaging of Human Carotid Atherosclerotic Plaques Using Ultrasonography

2011 ◽  
Author(s):  
Renate W. Boekhoven ◽  
Marcel C. M. Rutten ◽  
Marc R. H. M. van Sambeek ◽  
Frans N. van de Vosse
Keyword(s):  
Mechanical Properties ◽  
Carotid Artery ◽  
Carotid Endarterectomy ◽  
Early Stage ◽  
Three Dimensional ◽  
Atherosclerotic Plaques ◽  
Unstable Plaques ◽  
Human Carotid ◽  
Selection Of

Ruptured atherosclerotic plaques in the carotid artery are the main cause of stroke (70–80%). To prevent it, carotid endarterectomy is the procedure of choice in patients with a recent symptomatic 70–99% stenosis. Today, the selection of candidates is based on stenosis size only. However, endarterectomy is beneficial for only 1 out of 6 patients [1], the patients with unstable plaques (Fig. 1). Knowledge of mechanical properties of different components in the atherosclerotic arteries is important, because it will allow the identification of plaque stability at an early stage.

Numerical Simulation of Carotid Hemodynamics in Patients with Rotary Blood Pump Cardiac Assist

2003 ◽  
Vol 26 (2) ◽  
pp. 152-160 ◽  
Author(s):  
H. Schima ◽  
B. Lackner ◽  
M. Prosi ◽  
K. Perktold
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
Fluid Exchange ◽  
Local Flow ◽  
Cardiac Assist ◽  
Pulsatile Shear Stress ◽  
Local Mean ◽  
Plaque Growth ◽  
Rotary Blood Pumps

In recipients of rotary blood pumps for cardiac assist, the pulsatility of arterial flow is considerably diminished. This influences the shear stress patterns and streamlines in the arterial bed, with potential influence on washout and subsequent plaque growth. To study these effects, a three-dimensional computer simulation of the carotid bifurcation at various levels of flow pulsatility was performed. The results showed that as expected pulsatile shear stress varied considerably, whereas local mean shear stress levels were nearly identical for all degrees of pulsatility. Particle residence time in the carotid bulb did only increase for less than 15%, with secondary washout patterns contributing to good washout also in nonpulsatile conditions. It is concluded that also under continuous pump support the local flow patterns in the carotids provide sufficient washout and fluid exchange to prevent excessive plaque growth.

Targeted Particle Tracking in Computational Models of Human Carotid Bifurcations

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Ian Marshall
Keyword(s):  
Healthy Volunteer ◽  
Carotid Artery ◽  
Flow Region ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
External Carotid ◽  
Complex Flow ◽  
Imaging Science ◽  
Carotid Bulb ◽  
Human Carotid

A significant and largely unsolved problem of computational fluid dynamics (CFD) simulation of flow in anatomically relevant geometries is that very few calculated pathlines pass through regions of complex flow. This in turn limits the ability of CFD-based simulations of imaging techniques (such as MRI) to correctly predict in vivo performance. In this work, I present two methods designed to overcome this filling problem, firstly, by releasing additional particles from areas of the flow inlet that lead directly to the complex flow region (“preferential seeding”) and, secondly, by tracking particles both “downstream” and “upstream” from seed points within the complex flow region itself. I use the human carotid bifurcation as an example of complex blood flow that is of great clinical interest. Both idealized and healthy volunteer geometries are investigated. With uniform seeding in the inlet plane (in the common carotid artery (CCA)) of an idealized bifurcation geometry, approximately half the particles passed through the internal carotid artery (ICA) and half through the external carotid artery. However, of those particles entering the ICA, only 16% passed directly through the carotid bulb region. Preferential seeding from selected regions of the CCA was able to increase this figure to 47%. In the second method, seeding of particles within the carotid bulb region itself led to a very high proportion (97%) of pathlines running from CCA to ICA. Seeding of particles in the bulb plane of three healthy volunteer carotid bifurcation geometries led to much better filling of the bulb regions than by particles seeded at the inlet alone. In all cases, visualization of the origin and behavior of recirculating particles led to useful insights into the complex flow patterns. Both seeding methods produced significant improvements in filling the carotid bulb region with particle tracks compared with uniform seeding at the inlet and led to an improved understanding of the complex flow patterns. The methods described may be combined and are generally applicable to CFD studies of fluid and gas flow and are, therefore, of relevance in hemodynamics, respiratory mechanics, and medical imaging science.

Relation between histological age-changes in the carotid body and atherosclerosis in the carotid arteries

1987 ◽  
Vol 101 (12) ◽  
pp. 1271-1275 ◽  
Author(s):  
Patrick Lowe ◽  
Donald Heath ◽  
Paul Smith
Keyword(s):  
Blood Flow ◽  
Carotid Body ◽  
Carotid Arteries ◽  
Carotid Sinus ◽  
Carotid Bifurcation ◽  
Age Changes ◽  
Histological Changes ◽  
Atherosclerotic Lesions ◽  
Flow Through ◽  
Human Carotid

Abstract Histological changes in the human carotid body associated with increasing age are accompanied by occlusive atherosclerotic lesions in the arteries of the carotid bifurcation, and are probably ischaemic in origin. The carotid sinus, however, is unusually susceptible to the development of atheroma and its occlusion appears to have little influence in compromising blood flow through the glomic arteries.

scholarly journals Turbulence Modeling in Three-Dimensional Stenosed Arterial Bifurcations

2006 ◽  
Vol 129 (1) ◽  
pp. 40-50 ◽  
Author(s):  
J. Banks ◽  
N. W. Bressloff
Keyword(s):  
Carotid Artery ◽  
Turbulence Modeling ◽  
Turbulent Viscosity ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Shape Variation ◽  
Severe Stenosis ◽  
Carotid Artery Bifurcation ◽  
Inflow Turbulence ◽  
Flow Through

Under normal healthy conditions, blood flow in the carotid artery bifurcation is laminar. However, in the presence of a stenosis, the flow can become turbulent at the higher Reynolds numbers during systole. There is growing consensus that the transitional k−ω model is the best suited Reynolds averaged turbulence model for such flows. Further confirmation of this opinion is presented here by a comparison with the RNG k−ϵ model for the flow through a straight, nonbifurcating tube. Unlike similar validation studies elsewhere, no assumptions are made about the inlet profile since the full length of the experimental tube is simulated. Additionally, variations in the inflow turbulence quantities are shown to have no noticeable affect on downstream turbulence intensity, turbulent viscosity, or velocity in the k−ϵ model, whereas the velocity profiles in the transitional k−ω model show some differences due to large variations in the downstream turbulence quantities. Following this validation study, the transitional k−ω model is applied in a three-dimensional parametrically defined computer model of the carotid artery bifurcation in which the sinus bulb is manipulated to produce mild, moderate, and severe stenosis. The parametric geometry definition facilitates a powerful means for investigating the effect of local shape variation while keeping the global shape fixed. While turbulence levels are generally low in all cases considered, the mild stenosis model produces higher levels of turbulent viscosity and this is linked to relatively high values of turbulent kinetic energy and low values of the specific dissipation rate. The severe stenosis model displays stronger recirculation in the flow field with higher values of vorticity, helicity, and negative wall shear stress. The mild and moderate stenosis configurations produce similar lower levels of vorticity and helicity.

Mixing in the Human Carotid Artery during Carotid Drug Infusion Studied with PET

1989 ◽  
Vol 9 (5) ◽  
pp. 681-689 ◽  
Author(s):  
Larry Junck ◽  
Robert A. Koeppe ◽  
Harry S. Greenberg
Keyword(s):  
Carotid Artery ◽  
Carotid Bifurcation ◽  
Drug Infusion ◽  
Arterial Infusion ◽  
Positron Emission ◽  
Volume Of Interest ◽  
Wide Range ◽  
Vinyl Tube ◽  
Catheter Tip ◽  
Human Carotid

The safety and efficacy of drug infusion into the carotid artery require adequate mixing of the infused solution with carotid blood. Using positron emission tomography (PET), we studied the mixing of solutions infused into the human carotid artery in seven patients by analyzing the distribution of [15O]H2O infused into the carotid artery and by vein. At four infusion rates ranging from 0.5 to 10 ml/min, the variability in distribution averaged 16.5–17.8% among the pixels in a large volume of interest, without dependence on the infusion rate. The overall correlation between [15O]H2O influx with arterial infusion and [15O]H2O influx with venous injection was 0.78–0.82 at the four infusion rates, with no trend toward higher correlations at the faster infusion rates. The distribution into the anterior, middle, and posterior cerebral artery territories differed from distribution throughout the entire carotid territory by an average of 6.2–9.6% at the four infusion rates, with no trend toward smaller differences at the faster infusion rates. Infusions performed into a vinyl tube simulating the carotid artery indicated that at 0.5 ml/min, the velocity of fluid exiting the catheter makes no apparent contribution to mixing. We conclude that with infusions at the carotid bifurcation, mixing in the human carotid artery is complete or nearly complete over a wide range of infusion rates. The mixing appears to result from the patterns of blood flow within the artery, and not from jet effects at the catheter tip.

On the Mechanism of the Cardiazol Convulsion

1939 ◽  
Vol 85 (356) ◽  
pp. 392-405 ◽  
Author(s):  
D. J. Watterson ◽  
R. Macdonald
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Carotid Artery ◽  
Intravenous Injection ◽  
Carotid Sinus ◽  
Digital Pressure ◽  
The Central Nervous System ◽  
The Brain ◽  
Human Carotid

Experiments were performed to answer the elementary question whether cardiazol, after intravenous injection, has time to reach the central nervous system before the fit occurs. The question is not entirely superfluous for two reasons: first because several workers have reported convulsions occurring immediately after the injection, or even before the injection is completed, whereas in normal persons the average time taken for blood to circulate from the antecubital veins to the carotid sinus under resting conditions is 15·6 seconds (East and Bain (1936)), and from the carotid artery to the brain probably 1 second (Wolff and Blumgart (1929)); second, because it is important to decide whether the carotid sinus plays a part in the mechanism of the fit, since it is known that stimulation (by digital pressure) of the hypersensitive human carotid sinus will cause unconsciousness and convulsions (Weiss and Baker (1933)).

Age-Dependent Morphological Changes of the Human Carotid Bifurcation

1999 ◽  
Author(s):  
Baruch B. Lieber ◽  
Ajay K. Wakhloo ◽  
Andreas R. Luft ◽  
Afshin A. Divani
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Carotid Sinus ◽  
Subsequent Development ◽  
Carotid Bifurcation ◽  
Support Pressure ◽  
Morphological Development ◽  
Sinus Wall ◽  
The Brain ◽  
Human Carotid

Abstract The development, significance and function of the human carotid sinus is not yet well understood. The arterial wall within the carotid sinus is well enervated and it contains baroreceptive neural terminals. One hypothesis that was put forward is that the dilation, which may involve all vessels of the carotid bifurcation, exists to support pressure sensing1. Another hypothesis that is supported only by phenomenological observations assume that the function of the sinus is to protect the brain by slowing blood flow and reducing pulsatility2. Yet another hypothesis interprets the sinus as an ontogenetic or phylogenic residual3. More recently, carotid hemodynamics has been investigated using in vitro and computational models. Flow patterns in the carotid sinus were found to be complex and as such have been implicated in the hetrogenesis and subsequent development of atherosclerosis at this site. However, the development of this unique sinus morphology, the role of hemodynamics in such development, and the physiological implications created by this unique morphology have not been investigated. Understanding the hemodynamic and developmental forces that play a role in remodeling of the carotid bifurcation and development of the sinus is of both fundamental and clinical interest and can lead to better prognostication and therapy of carotid disease. Therefore, we initiated a study of the morphological development of the human carotid bulb using different age groups under the hypothesis that sinus morphology reflects an adaptive change in response to alterations in cerebral blood supply during the developmental years of the brain. This adaptation attempts to reduce hydraulic losses in the carotid bifurcation through reduced flow disturbances and maintain high level of blood supply to the brain than consumes about 15% of cardiac output under basal conditions. In addition, it may protect the sinus wall from high shear stress and/or the brain from highly pulsatile blood flow conditions. Initially, we analyzed the angle and sinus morphology of the carotid bifurcation in pediatric and adult patients using biplane digital subtraction angiograms to characterize changes that occur as the brain matures.

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