Vascular Hemodynamics with Computational Modeling and Experimental Studies

Beier, Susann; Ormiston, John A.; Webster, Mark; Cater, John; Norris, Stuart; Medrano-Gracia, Pau; Young, Alistair A.; Cowan, Brett R.

doi:10.1016/b978-0-12-811018-8.00009-6

Cited by 5 publications

(4 citation statements)

References 79 publications

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“…A limitation of this work is that other coronary shape characteristics, such as the vessel diameter profile, may also affect the hemodynamic correlation predicted and may even have interdependent effects with tortuosity 54 . However, as this is a comparative analysis, it should be interpreted not as an attempt to predict TAWSS solely from tortuosity since other arterial geometric characteristics likely have an interdependent effect 55 , and thus it is sensible that the R 2 values obtained are low.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of vascular tortuosity measures using computational modelling

Kashyap

Gharleghi

et al. 2022

Sci Rep

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Severe coronary tortuosity has previously been linked to low shear stresses at the luminal surface, yet this relationship is not fully understood. Several previous studies considered different tortuosity metrics when exploring its impact of on the wall shear stress (WSS), which has likely contributed to the ambiguous findings in the literature. Here, we aim to analyze different tortuosity metrics to determine a benchmark for the highest correlating metric with low time-averaged WSS (TAWSS). Using Computed Tomography Coronary Angiogram (CTCA) data from 127 patients without coronary artery disease, we applied all previously used tortuosity metrics to the left main coronary artery bifurcation, and to its left anterior descending and left circumflex branches, before modelling their TAWSS using computational fluid dynamics (CFD). The tortuosity measures included tortuosity index, average absolute-curvature, root-mean-squared (RMS) curvature, and average squared-derivative-curvature. Each tortuosity measure was then correlated with the percentage of vessel area that showed a < 0.4 Pa TAWSS, a threshold associated with altered endothelial cell cytoarchitecture and potentially higher disease risk. Our results showed a stronger correlation between curvature-based versus non-curvature-based tortuosity measures and low TAWSS, with the average-absolute-curvature showing the highest coefficient of determination across all left main branches (p < 0.001), followed by the average-squared-derivative-curvature (p = 0.001), and RMS-curvature (p = 0.002). The tortuosity index, the most widely used measure in literature, showed no significant correlation to low TAWSS (p = 0.86). We thus recommend the use of average-absolute-curvature as a tortuosity measure for future studies.

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Section: Discussionmentioning

confidence: 99%

Accuracy of vascular tortuosity measures using computational modelling

Kashyap

Gharleghi

et al. 2022

Sci Rep

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“…Moreover, the flow phantom utilized in this study was scaled-up. To overcome the spatial restrictions, the scaling of vascular replicas based on the principle of dynamic similarity, also known as dynamic scaling, has been widely used in the in-vitro experiments [56–59]. The dynamic scaling is a well-established concept that ensures the development of flow in scaled phantom identical to the original object.…”

Section: Discussionmentioning

confidence: 99%

PIV investigation of the flow fields in subject-specific vertebro-basilar (VA-BA) junction

et al. 2019

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Background As the only arterial structure of which two main arteries merged into one, the vertebro-basilar (VA-BA) system is one of the favorite sites of cerebral atherosclerotic plaques. The aim of this study was to investigate the detailed hemodynamics characteristics in the VA-BA system. Methods A scale-up subject-specific flow phantom of VA-BA system was fabricated based on the computed tomography angiography (CTA) scanning images of a healthy adult. Flow fields in eight axial planes and six radial planes were measured and analyzed by using particle image velocimetry (PIV) under steady flow conditions of , . A water–glycerin mixture was used as the working fluid. Results The flow in the current model exhibited highly three-dimensional characteristics. The confluence of VAs flow formed bimodal velocity distribution near the confluence apex. Due to the asymmetrical structural configuration, the bimodal velocity profile skewed towards left, and sharper peaks were observed under higher Reynolds condition. Secondary flow characterized by two vortices formed in the radial planes where 10 mm downstream the confluence apex and persists along the BA under both Reynolds numbers. The strength of secondary flow under is around 8% higher than that under , and decayed nonlinearly along the flow direction. In addition, a low momentum recirculation region induced by boundary layer separation was observed near the confluence apex. The wall shear stress (WSS) in the recirculation area was found to be lower than 0.4 Pa. This region coincides well with the preferential site of vascular lesions in the VA-BA system. Conclusions This preliminary study verified that the subject-specific in-vitro experiment is capable of reflecting the detailed flow features in the VA-BA system. The findings from this study may help to expand the understanding of the hemodynamics in the VA-BA system, and further clarifying the mechanism that underlying the localization of vascular lesions.

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“…The coronary artery CTCA images were available to us through the Coronary Atlas 13 , an ongoing collection of CTCA images and associated clinical and demographics data used to investigate differences in coronary anatomy 14 and haemodynamic behaviour between patients [15][16][17] . A set of 40 patient-specific coronary artery tree data is provided here, including anonymized CTCA images in .nrdd format, combined high-quality manual voxel annotations derived from 3 experts, and other associated data such as centrelines, smoothed meshes in .stl format and calcification scores.…”

Section: Background and Summarymentioning

confidence: 99%

Annotated computed tomography coronary angiogram images and associated data of normal and diseased arteries

et al. 2023

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Computed Tomography Coronary Angiography (CTCA) is a non-invasive method to evaluate coronary artery anatomy and disease. CTCA is ideal for geometry reconstruction to create virtual models of coronary arteries. To our knowledge there is no public dataset that includes centrelines and segmentation of the full coronary tree. We provide anonymized CTCA images, voxel-wise annotations and associated data in the form of centrelines, calcification scores and meshes of the coronary lumen in 20 normal and 20 diseased cases. Images were obtained along with patient information with informed, written consent as part of the Coronary Atlas. Cases were classified as normal (zero calcium score with no signs of stenosis) or diseased (confirmed coronary artery disease). Manual voxel-wise segmentations by three experts were combined using majority voting to generate the final annotations. Provided data can be used for a variety of research purposes, such as 3D printing patient-specific models, development and validation of segmentation algorithms, education and training of medical personnel and in-silico analyses such as testing of medical devices.

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Vascular Hemodynamics with Computational Modeling and Experimental Studies

Cited by 5 publications

References 79 publications

Accuracy of vascular tortuosity measures using computational modelling

Accuracy of vascular tortuosity measures using computational modelling

PIV investigation of the flow fields in subject-specific vertebro-basilar (VA-BA) junction

Annotated computed tomography coronary angiogram images and associated data of normal and diseased arteries

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