scholarly journals Exploring the Relationships Between Hemodynamic Stresses in the Carotid Arteries

2021 ◽  
Vol 7 ◽  
Author(s):  
Magnus Ziegler ◽  
Jesper Alfraeus ◽  
Elin Good ◽  
Jan Engvall ◽  
Ebo de Muinck ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Carotid Arteries ◽  
Carotid Bifurcation ◽  
Vessel Diameter ◽  
Atherosclerotic Plaques ◽  
Shear Stresses ◽  
Strongly Correlated ◽  
4D Flow ◽  
Bifurcation Angle

Background: Atherosclerosis manifests as a focal disease, often affecting areas with complex hemodynamics such as the carotid bifurcation. The magnitude and regularity of the hemodynamic shear stresses acting on the vessel wall are thought to generate risk patterns unique to each patient and play a role in the pathogenesis of atherosclerosis. The involvement of different expressions of shear stress in the pathogenesis of carotid atherosclerosis highlights the need to characterize and compare the differential impact of the various expressions of shear stress in the atherosclerotic carotid bifurcation. Therefore, the aim of this study is to characterize and compare hemodynamic wall shear stresses (WSS) in the carotid arteries of subjects with asymptomatic atherosclerotic plaques. Shear stresses were also compared against vessel diameter and bifurcation angle to examine the relationships with the geometry of the carotid bifurcation.Methods: 4D Flow MRI and contrast-enhanced MRA data were acquired for 245 subjects with atherosclerotic plaques of at least 2.7 mm in conjunction with the Swedish CArdioPulmonary bioImage Study (SCAPIS). Following automatic segmentation and geometric analysis, time-resolved WSS and near-wall turbulent kinetic energy (nwTKE) were derived from the 4D Flow data. Whole-cycle parameters including time-averaged WSS and nwTKE, and the oscillatory shear index (OSI) were calculated. Pairwise Spearman rank-correlation analyses were used to investigate relationships among the hemodynamic as well as geometric parameters.Results: One hundred and seventy nine subjects were successfully segmented using automated tools and subsequently geometric and hemodynamic analyses were performed. Temporally resolved WSS and nwTKE were strongly correlated, ρ = 0.64. Cycle-averaged WSS and nwTKE were moderately correlated, ρ = 0.57. Cycle-average nwTKE was weakly correlated to OSI (ρ = −0.273), revealing that nwTKE provides information about disturbed flow on the vessel wall that OSI does not. In this cohort, there was large inter-individual variation for both WSS and nwTKE. Both WSS and nwTKE varied most within the external carotid artery. WSS, nwTKE, and OSI were weakly correlated to vessel diameter and bifurcation angle.Conclusion: The turbulent and mean component of WSS were examined together in vivo for the first time, and a strong correlation was found between them. nwTKE presents the opportunity to quantify turbulent wall stresses in vivo and gain insight into the effects of disturbed flow on the vessel wall. Neither vessel diameter nor bifurcation angle were found to be strongly correlated to the turbulent or mean component of WSS in this cohort.

High Resolution Magnetic Resonance Imaging of Resected Plaque

1997 ◽  
Vol 3 (S2) ◽  
pp. 309-310
Author(s):  
D. Saloner
Keyword(s):  
Atherosclerotic Plaque ◽  
Carotid Bifurcation ◽  
Surgical Removal ◽  
Strongly Correlated ◽  
Clinical Events ◽  
Significant Events ◽  
Diseased Vessel ◽  
Clinically Significant ◽  
Substantial Interest

Atherosclerotic plaque at the carotid bifurcation is strongly correlated with the incidence of clinically significant events, such as transient ischemie attacks or stroke. Large multi-center trials have demonstrated that surgical removal of the atheroma is more effective in reducing these clinical events than is medical treatment alone. Patients are selected for surgery from an assessment of the severity of disease at the carotid bifurcation. The measure of disease severity is conventionally taken to be the degree of narrowing of the diseased vessel compared to a normal segment of vessel. However, using this criterion alone, many patients receive endarterectomy surgery who would probably not have progressed to other neurological events, while others are excluded who do progress to neurological events. For this reason, there is substantial interest in methods that could evaluate the composition of the atherosclerotic plaque in vivo, with the hope that this information would improve the predictive power of pre-surgical imaging of the diseased vessel.

On the Importance of Assumptions for Bulk Flow in Hemodynamic Models of the Carotid Bifurcation

2011 ◽  
Author(s):  
Umberto Morbiducci ◽  
Diana Massai ◽  
Diego Gallo ◽  
Raffaele Ponzini ◽  
Marco A. Deriu ◽  
...  
Keyword(s):  
Vessel Wall ◽  
Carotid Bifurcation ◽  
Flow Fields ◽  
Transport Processes ◽  
Bulk Flow ◽  
Arterial System ◽  
Vortical Flow ◽  
Primary Role ◽  
4D Flow ◽  
The Impact

It is widely accepted that the local hemodynamics in the arterial system affects the atherogenic process. In particular the hemodynamic environment at the carotid artery bifurcation has been widely studied due to its predilection for atherosclerosis. Much effort has been spent in the past on image-based CFD carotid bifurcation models to assess the sensitivity to several assumptions of wall shear stress (WSS)-based parameters as indicators of abnormal flow. This luminal-surface-oriented approach was historically driven by histological observations on samples of the vessel wall. The consequence for this was that the reduction of the complexity of 4D flow fields focused mainly on WSS. However, few studies have provided adequate insights into the influence of these assumptions in order to confidently model the 4D hemodynamics within the bifurcation. Only recently the interest in the role played by the bulk flow in the development of the arterial disease has grown dramatically. This is the consequence of the emerging awareness that arterial hemodynamics, being an intricate process that involves interaction, reconnection and continuous re-organization of structures, could play a primary role in the regulation of mass transfer, and of its athero-protective/susceptible effect. Earlier works [1] pointed out the existence of a relationship between helical/vortical flow patterns and transport processes that could affect blood-vessel wall interaction, and might cause alterations in the residence time of atherogenic particles involved in the initiation of inflammatory response. Recently we introduced robust quantitative descriptors of bulk flow that can “reduce” the inherent complexity associated with 4D flow fields in arteries [1]. Here we present a study on the impact of assumptions on blood rheology and outflow boundary conditions (BCs) on bulk flow features within healthy carotid bifurcations, by using 4D flow descriptors. The final goal is to provide adequate insights not only to complement and to integrate, but also to extend with a quantitative characterization of the bulk flow the description currently adopted to classify altered hemodynamics.

scholarly journals In vivo cardiovascular magnetic resonance of 2D vessel wall diffusion anisotropy in carotid arteries

2016 ◽  
Vol 18 (1) ◽  
Author(s):  
Peter Opriessnig ◽  
Harald Mangge ◽  
Rudolf Stollberger ◽  
Hannes Deutschmann ◽  
Gernot Reishofer
Keyword(s):  
Cardiovascular Magnetic Resonance ◽  
Magnetic Resonance ◽  
Vessel Wall ◽  
Carotid Arteries ◽  
Diffusion Anisotropy

DIAGNOSTIC AND THERAPEUTIC TREATMENTS OF PLAQUES IN THE CAROTID BIFURCATION — STUDIES IN MODELS WITH STENTS AND FILTERS

2014 ◽  
Vol 14 (03) ◽  
pp. 1450030
Author(s):  
D. LIEPSCH ◽  
A. BALASSO ◽  
C. ZIMMER ◽  
H. BERGER ◽  
R. BURKHART ◽  
...  
Keyword(s):  
Flow Rate ◽  
Fluid Dynamic ◽  
Flow Behavior ◽  
Carotid Bifurcation ◽  
Flow Rate Ratio ◽  
Shear Stresses ◽  
Dynamic Factors ◽  
Rate Ratios ◽  
Visualization Techniques

Fluid dynamics, especially forces and velocity distribution, influence the development of plaques. Flow parameters: pulsatility, the non-Newtonian flow behavior of blood and wall elasticity are considered. Flow visualization techniques (dyes and birefringent solution with a photo-elasticity apparatus) and LDA measurements demonstrate the importance of the flow. Accurate in vivo velocity measurements are necessary to calculate shear stresses. Different bifurcation angles and flow rate ratios were tested in true to life artery models. The most important fluid dynamic factors at bifurcations are the flow rate ratio and the geometry which create flow separation regions which are responsible for platelet aggregation and intima damage. It is necessary to measure all three velocity components to calculate the velocity vector. The highest shear stresses in a healthy carotid artery are 16 Pa and are found just at the apex. In artery models with 90% stenosis, shear stresses up to 250 Pa were found. Distally, vortices were created where particles remained over several pulse cycles. Measurements show that stents must be selected carefully and placed precisely. Filters must be closed during the systolic phase before removal, so that no trapped particles can escape.

GLA-CONTAINING PROTEINS FROM CALCIFIED HUMAN ATHEROSCLEROTIC PLAQUES

1987 ◽  
Author(s):  
L J M Van Haarlem ◽  
H C Hemker ◽  
B A M Soute ◽  
C Vermeer
Keyword(s):  
Vitamin K ◽  
Vessel Wall ◽  
High Performance ◽  
Gel Filtration ◽  
Coagulation Factors ◽  
Atherosclerotic Plaques ◽  
Factor X ◽  
Carboxylase Activity

Vitamin K-dependent carboxylase activity has been detected in human andbovine vessel wall. Studies comparingthe carboxylases from liver and vessel wall revealed that the enzyme systems may be regarded as isoenzymes withwidely different substrate specificities. The carboxylated product of vessel wall carboxylase has not yet been identified, but it seems plausible that it will be found amongst the Gla-containing proteins which are abundantly present in calcified atherosclerotic plaques (Gla= gammacarboxyglutamicacid, the abnormal amino acid formed by vitamin K-dependent carboxylase). Therefore we have started to characterize the protein constituents of hardened atherosclerotic plaques.The calcified areas from human aortae were solubilized in EDTA and the proteins extracted were partly purified by batch-wise adsorption onto QAE and elution with high salt. The crudeplaque-extract did not contain prothrombin, factor X or protein C. This excludes the possibility that Gla-containing coagulation factors are bound non-specifically from blood. Osteocalcin accounted for 20% of the total amount of protein-bound Gla-residues.Another Gla-containing protein waspurified from the crude plaque-extract by employing high performance liquid chromatography (HPLC). Gel filtration yielded a Gla-rich protein with anapparent Mr of 25 kD. In vitro boththe crude plaque-extract and the purified Gla-containing protein strongly inhibited the precipitation of calcium phosphate and calcium carbonate. A similar effect was not found with humanserum albumin nor with a thermallydecarboxylated plaque-extract. If also in vivo the Gla-containing proteinsproduced by vessel wall carboxylase prevent the precipitation of calcium salts remains to be investigated.

CFD and VH-IVUS Biomechanical Analysis of Coronary Artery Disease With One Year Follow-Up

2013 ◽  
Author(s):  
David S. Molony ◽  
Lucas H. Timmins ◽  
Parham Eshtehardi ◽  
Habib Samady ◽  
Don P. Giddens
Keyword(s):  
Coronary Artery Disease ◽  
Biomechanical Analysis ◽  
Atherosclerotic Plaques ◽  
Shear Stresses ◽  
Plaque Progression ◽  
Focal Lesions ◽  
Artery Disease ◽  
One Year

Coronary atherosclerotic plaques are frequently focal lesions that have variable rates of progression. Wall shear stresses (WSS) create a number of responses in endothelial cells that can lead to the localization and progression of these lesions, and in vivo coronary segments with low WSS have been found to develop greater plaque progression than segments of higher WSS.

scholarly journals Imaging Collagen in Intact Viable Healthy and Atherosclerotic Arteries Using Fluorescently Labeled CNA35 and Two-Photon Laser Scanning Microscopy

2007 ◽  
Vol 6 (4) ◽  
pp. 7290.2007.00021 ◽  
Author(s):  
Remco T.A. Megens ◽  
Mirjam G.A. oude Egbrink ◽  
Jack P.M. Cleutjens ◽  
Marijke J.E. Kuijpers ◽  
Paul H.M. Schiffers ◽  
...  
Keyword(s):  
Molecular Imaging ◽  
Apolipoprotein E ◽  
Carotid Arteries ◽  
Ex Vivo ◽  
Atherosclerotic Plaques ◽  
Type I ◽  
Two Photon ◽  
Tunica Adventitia ◽  
Molecular Imaging Agent

We evaluated CNA35 as a collagen marker in healthy and atherosclerotic arteries of mice after both ex vivo and in vivo administration and as a molecular imaging agent for the detection of atherosclerosis. CNA35 conjugated with fluorescent Oregon Green 488 (CNA35/OG488) was administered ex vivo to mounted viable muscular (uterine), elastic (carotid), and atherosclerotic (carotid) arteries and fresh arterial rings. Two-photon microscopy was used for imaging. CNA35/OG488 labeling in healthy elastic arteries was compared with collagen type I, III, and IV antibody labeling in histologic sections. For in vivo labeling experiments, CNA35/OG488 was injected intravenously in C57BL6/J and apolipoprotein E−/− mice. Ex vivo CNA35/OG488 strongly labeled collagen in the tunica adventitia, media, and intima of muscular arteries. In healthy elastic arteries, tunica adventitia was strongly labeled, but labeling in tunica media and intima was prevented by endothelium and elastic laminae. Histology confirmed the affinity of CNA35 for type I, III, and IV collagen in arteries. Strong CNA35/OG488 labeling was found in atherosclerotic plaques. In vivo applied CNA35/OG488 minimally labeled the tunica intima of healthy carotid arteries. Atherosclerotic plaques in apolipoprotein E−/− mice exhibited large uptake. CNA35/OG488 imaging in organs revealed endothelium as a limiting barrier for in vivo uptake. CNA35/OG488 is a good molecular imaging agent for atherosclerosis.

Concentration profile of blood platelets differs in arterioles and venules

1992 ◽  
Vol 262 (4) ◽  
pp. H1217-H1223 ◽  
Author(s):  
B. Woldhuis ◽  
G. J. Tangelder ◽  
D. W. Slaaf ◽  
R. S. Reneman
Keyword(s):  
Vessel Wall ◽  
Unit Volume ◽  
Dextran Sulfate ◽  
Blood Platelets ◽  
Median Plane ◽  
Vessel Diameter ◽  
Mean Values ◽  
Acridine Red ◽  
The Mean

Platelet distribution was investigated in 21 venules (V) and 10 arterioles (A) of the rabbit mesentery (vessel diam 15-33 microns). Circulating platelets were labeled in vivo with the dye acridine red and observed with fluorescence video microscopy. Only platelets flowing in a thin (5-7 microns) optical section located about the median plane of the vessel were used. The relative position of each platelet, i.e., the distance of its centroid to the left vessel wall divided by the local vessel diameter, was determined. In addition, in 10 venules leukocyte margination was inhibited by intravenous injection of dextran sulfate (500,000 mol wt; 30 mg/kg body wt). The number of platelets per unit volume (i.e., platelet density) relative to the mean density was significantly higher in the vessel center of V (1.04) than of A (0.55; P less than 0.005). In contrast, near the wall this density was significantly higher in A compared with V. Mean values were as follows: at radial position (R) = 0.9-1.0, 0.30 in A and 0.11 in V (P greater than 0.05); at R = 0.8-0.9, 1.63 in A and 0.84 in V (P less than 0.002); at R = 0.7-0.8, 1.60 in A and 1.36 in V (P greater than 0.05); at R = 0.6-0.7, 1.16 in A and 1.60 in V (P less than 0.02); and at R = 0.5-0.6, 0.92 in A and 1.36 in V (P less than 0.02). These differences in platelet distribution between arterioles and venules are not caused by the presence of leukocyte margination in venules.

Distensibility of the Atherosclerotic Carotid Artery: Relationship With Plaque Burden and Composition?

2012 ◽  
Author(s):  
Gador Canton ◽  
Dalin Tang ◽  
Daniel S. Hippe ◽  
Chun Yuan
Keyword(s):  
Vessel Wall ◽  
Structural Changes ◽  
Carotid Arteries ◽  
Plaque Burden ◽  
Cine Mri ◽  
Arterial Distensibility ◽  
Biomechanical Models ◽  
Imaging Tool ◽  
Wall Stiffness

Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis [5] with applications including estimation of mechanical properties of the wall for biomechanical models. Although arterial segments affected by atherosclerosis are characterized by marked stiffening [2], little is known about the relationship between local specific atherosclerotic plaque features and wall stiffness. In particular, calcification has been shown to be associated with greater wall stiffness, however, this relationship is not consistent in different arterial segments [1,6]. For the carotid arteries, a more thorough understanding of the role of plaque features in determining wall stiffness might be offered by magnetic resonance imaging (MRI). Multi-contrast, high resolution MRI is an established imaging tool to quantify the components of carotid lesions, as well as plaque burden [8,9]. In addition, CINE MRI has been proven to be a reliable tool to measure arterial distensibility [3], an index frequently used to measure stiffness. In this study, our goals were to use MRI to characterize subject-specific wall stiffness in vivo in atherosclerotic carotid arteries, and to analyze the relation between stiffness and plaque burden and composition. CINE MRI was used to measure vessel wall stiffness; whereas a multi-contrast MRI protocol was applied to characterize vessel wall morphology and composition.

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