Coronary Artery Geometry and Its Fluid Mechanical Implications

Nerem, R. M.; Seed, W. A.

doi:10.1007/978-3-642-69085-3_7

Cited by 16 publications

(3 citation statements)

References 18 publications

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“…Specific areas of disease tend to be concentrated proximally in all major coronary branches with an asymmetric distribution around each respective circumference. 6 While these observations point directly to fluid mechanic implications towards atheroma evolution, it remains that the hypothesis of geometrical implications on shear stress variations within the coronary arteries has yet to be effectively tested. In particular, since the added constraint on the coronaries is that of time-dependent movement of vessel curvature, torsion, rotation, wall diameter, and length, 7 in totality the hemodynamic implications in the coronary vessels, taking the geometrical changes into account is highly complex.…”

Section: Introductionmentioning

confidence: 98%

<title>Four-dimensional coronary morphology and computational hemodynamics</title>

et al. 2001

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Conventional reconstructions from intravascular ultrasound (IVUS) stack the frames as acquired during the pullback of the catheter to form a straight three-dimensional volume, thus neglecting the vessel curvature and merging images from different heart phases. We are developing a comprehensive system for fusion of the IVUS data with the pullback path as determined from x-ray angiography, to create a geometrically accurate 4-D (3-D plus time) model of the coronary vasculature as basis for computational hemodynamics. The overall goal of our work is to correlate shear stress with plaque thickness. The IVUS data are obtained in a single pullback using an automated pullback device; the frames are afterwards assigned to their respective heart phases based upon the ECG signal. A set of 3-D models is reconstructed by fusion of IVUS and angiographic data corresponding to the same ECG-gated heart phase; methods of computational fluid dynamics (CFD) are applied to obtain important hemodynamic data. Combining these models yields the final 4-D reconstruction. Visualization is performed using the platform-independent VRML standard for a user-friendly manipulation of the scene. An extension for virtual angioscopy allows an easy assessment of the vessel features within their local context. Validation was successfully performed both in-vitro and in-vivo.

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Section: Introductionmentioning

confidence: 98%

<title>Four-dimensional coronary morphology and computational hemodynamics</title>

et al. 2001

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“…[11][12][13][14] This is in part because of a lack of relevant data for the in vivo situation. Biplane cineangiography and intravascular ultrasound (IVUS) are 2 powerful modalities for assessing this relationship in vivo.…”

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confidence: 99%

Relationship Between the Dynamic Geometry and Wall Thickness of a Human Coronary Artery

Zhu

Friedman

2003

ATVB

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Objective-It is widely recognized that hemodynamic and wall mechanical forces are involved in the initiation and development of atherosclerosis. In the coronary vasculature, these forces are likely mediated by arterial dynamics and geometry. This research examines the hypothesis that coronary artery motion and geometry affect the local predisposition to disease, presumably through their influence on the stresses at and in the artery wall. Methods and Results-The dynamics of a human right coronary artery and the variation of wall thickness along its length were characterized from biplane cineangiograms and intravascular ultrasound records, respectively. The dynamic geometry parameters were distance along the vessel, cyclic displacement, axial strain, curvature, and torsion. Multiple regression analyses using principal components show that (1) no single dynamic geometry parameter has a dominant influence on wall thickness, (2) Key Words: coronary arteries Ⅲ dynamic geometry Ⅲ wall thickness Ⅲ biplane angiography Ⅲ intravascular ultrasound A lthough several cardiovascular risk factors, including hypercholesterolemia, hypertension, smoking, and diabetes, have been associated with coronary heart disease (CHD), 1,2 it is conventional knowledge among investigators in atherosclerosis that these factors can explain no more than half of the variability in the occurrence of atherosclerotic lesions or CHD. [3][4][5] This situation suggests that there are additional risk factors that predispose to arterial disease. Friedman and colleagues 6 -8 have proposed that variations in arterial geometry, including the dynamic characteristics of the coronary arteries, can contribute to some of the unexplained variation in cardiovascular risk. This idea is based on the abundant and increasing evidence that hemodynamics and vascular wall stresses play an important role in the initiation and development of atherosclerosis. 9,10 The fluid dynamic environment at the arterial wall depends on the geometry and motion of the channel through which the flow is passing, and geometries that promote an adverse hemodynamic milieu could constitute additional risk factors for disease. Similarly, the motion of the coronary arteries during the cardiac cycle can lead to cyclic stresses in the wall that may prompt an atherosclerotic response.Most research seeking associations between coronary artery geometry and vessel pathology has been based on autopsy hearts. [11][12][13][14] This is in part because of a lack of relevant data for the in vivo situation. Biplane cineangiography and intravascular ultrasound (IVUS) are 2 powerful modalities for assessing this relationship in vivo. While the former modality makes it possible to accurately reconstruct the time-dependent 3D course of the coronary vessels on the beating heart, the latter provides the necessary in vivo vessel wall morphology. In this study, we demonstrate the use of these diagnostic techniques to evaluate the relationship between the dynamic geometry and morphometry of a human right coronary ar...

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“…This SS value was chosen based on the upper limit of the average wall SS values measured or predicted in the human coronary artery, with reports of 6-25 dyn/cm 2 . [25][26][27] Adherent ECs were re-plated for 3 hrs and subjected to fluid SS again. Control whole cell populations were also plated for 3 hrs.…”

Section: Endothelial Cell Detachment Is Not An Entirely Random Processmentioning

confidence: 99%

Identification of a subpopulation of highly adherent endothelial cells for seeding synthetic vascular grafts

Wolfe,

Chen,

Chen

et al. 2023

Preprint

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ObjectiveThere is an unmet clinical need for a bypass graft that can be used as an alternative to an autologous vessel graft for the treatment of severe coronary artery disease. Small-diameter (<6mm) synthetic vascular grafts are not suitable because of unacceptable patency rates. This mainly occurs without an endothelial cell (EC) monolayer to prevent platelet activation, thrombosis, and intimal hyperplasia. While numerous studies have explored methods to improve EC adhesion to biomaterials, there are still no reliable methods to endothelialize small-diameter grafts, as most seeded ECs are lost due to exposure to fluid shear stress (SS) after implantation. The goal of this work is to determine if EC loss is a random process or if it is possible to predict which cells are more likely to remain adherent.Approach and ResultsIn initial studies, we sorted ECs using fluid SS and identified a subpopulation of ECs that are more likely to resist detachment. We use RNA-sequencing (RNA-seq) to examine gene expression of adherent ECs compared to the whole population to identify targets for improving adhesion. Fibronectin leucine rich transmembrane protein 2 (FLRT2), which encodes protein FLRT2, emerged as a candidate due to its downregulation in the adherent ECs and known role in cell adhesion. Using fluorescence activated cell sorting (FACS), we sorted ECs based on FLRT2 expression levels and demonstrated that ECs expressing low levels of FLRT2 exhibit greater retention under fluid SS in vitro.ConclusionFor the first time, we show EC detachment is not an entirely random process and we predicted which ECs were more likely to remain adherent on a vascular graft upon exposure to fluid SS. This provides validation for the concept that we can seed a small-diameter vascular graft only with highly adherent ECs to maintain a stable endothelium and improve graft patency rates.Non-standard Abbreviations and Acronymsendothelial cell (EC), shear stress (SS), fibronectin leucine rich transmembrane protein 2 (FLRT2), tissue engineered vascular graft (TEVG), fluorescence activated cell sorting (FACS)

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Coronary Artery Geometry and Its Fluid Mechanical Implications

Cited by 16 publications

References 18 publications

<title>Four-dimensional coronary morphology and computational hemodynamics</title>

<title>Four-dimensional coronary morphology and computational hemodynamics</title>

Relationship Between the Dynamic Geometry and Wall Thickness of a Human Coronary Artery

Identification of a subpopulation of highly adherent endothelial cells for seeding synthetic vascular grafts

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