Stenosis Indicators Applied to Patient-Specific Renal Arteries without and with Stenosis

Fuchs, Alexander; Berg, Niclas; Wittberg, Lisa Prahl

doi:10.3390/fluids4010026

Cited by 10 publications

(9 citation statements)

References 31 publications

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“…Additionally, in general, it can be observed that regions downstream of stenosis had lower TAWSS and higher OSI, which constitute risk factors for the incidence and progression of atherosclerosis [33]. These results are in good agreement with recent studies conducted in arterial stenosis [31], [33], [47].…”

Section: %supporting

confidence: 89%

“…It has also been observed that oscillatory WSS promotes atherosclerosis [31], [33]. However, this information is not given by the TAWSS.…”

Section: G Post-processingmentioning

confidence: 99%

“…When OSI is equal to 0, the flow is unidirectional. When OSI is equal to 0.5, it means that the WSS field is fully oscillatory [33].…”

Section: G Post-processingmentioning

confidence: 99%

“…These are important tools to predict disturbed flow conditions, to estimate the development of local atherosclerotic plaques, and also to understand atherosclerosis progression [32]. Indeed, it has recently been shown that both high WSS as well as low and, in particular, oscillatory WSS can play an important role in these processes [33]. For instance, Gaudio et al [18] compared the Newtonian and non-Newtonian Carreau-Yasuda model in patientspecific stenotic coronary arteries with different degrees of stenosis.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

2020

International Journal of Biology and Biomedical Engineering

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Atherosclerosis is a potentially serious illness where arteries become clogged with fatty substances called plaques. Over the years, this pathological condition has been deeply studied and computational fluid dynamics has played an important role in investigating the blood flow behavior. Commonly, the blood flow is assumed to be laminar and a Newtonian fluid. However, under a stenotic condition, the blood behaves as a non-Newtonian fluid and the pulsatile blood flow through coronary arteries could result in a transition from laminar to turbulent flow condition. The present study aims to analyze and compare numerically the blood flow behavior, applying the k-ω SST model and a laminar assumption. The effects of Newtonian and non-Newtonian (Carreau) models were also studied. In addition, the effect of the stenosis degree on velocity fields and wall shear stress based descriptors were evaluated. According to the results, the turbulent model is shown to give a better overall representation of pulsatile flow in stenotic arteries. Regarding, the effect of non-Newtonian modeling, it was found to be more significant in wall shear stress measurements than in velocity profiles. In addition, the appearance of recirculation zones in the 50% stenotic model was observed during systole, and a low TAWSS and high OSI were detected downstream of the stenosis which, in turn, are risk factors for plaque formation. Finally, the turbulence intensity measurements allowed to distinguish regions of recirculating and disturbed flow.

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Section: %supporting

confidence: 89%

“…It has also been observed that oscillatory WSS promotes atherosclerosis [31], [33]. However, this information is not given by the TAWSS.…”

Section: G Post-processingmentioning

confidence: 99%

“…When OSI is equal to 0, the flow is unidirectional. When OSI is equal to 0.5, it means that the WSS field is fully oscillatory [33].…”

Section: G Post-processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

2020

International Journal of Biology and Biomedical Engineering

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“…Wall Shear Stress-Sensitivity of Results to Boundary Condition. To assess the effect of change in inlet geometry and sensitivity to BCs, the following commonly used WSS related parameters were used: TAWSS, the OSI, and the relative residence time (RRT) [38,39].…”

Section: Resultsmentioning

confidence: 99%

Pulsatile Aortic Blood Flow—A Critical Assessment of Boundary Conditions

Fuchs

Berg

Wittberg

2020

Journal of Engineering and Science in Medical Diagnostics and Therapy

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Patient specific (PS) blood flow studies have become popular in recent years but have thus far had limited clinical impact. This is possibly due to uncertainties and errors in the underlying models and simulations set-up. This study focuses on the sensitivity of simulation results due to in- and outflow boundary conditions (BC:s). Nine different inlet- and seven different outlet BC:s were applied to two variants of a healthy subject's thoracic aorta. Temporal development of the flow is essential for the formation and development of helical/spiralling flow where the commonly observed clockwise helical motion may change direction during the heart-cycle. The sensitivity to temporal and spatial variations in the inlet conditions is significant both when expressed in terms of mean and maximal wall shear stress (WSS) and its different averaged variables, e.g. Time-Averaged WSS (TAWSS), Oscillating Shear Index (OSI) and Relative Residence Time (RRT). The simulation results are highly sensitive to BC. For example, the maximal WSS the results may vary over 3 orders of magnitude (1 to 1000 Pa) depending on particular combinations of BC:s. Moreover, certain formulations of outlet boundary conditions may be inconsistent of the computed flow field if the underlying assumptions of the space-time dependence are violated. The results of this study show that CFD simulations can reveal flow details that can enhance understanding of blood flows. However, the results also demonstrate the potential difficulties in mimicking blood flow in clinical situations.

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Numerical simulation in the abdominal aorta and the visceral arteries with or without stenosis based on 2D PCMRI

Chen

Liu

et al. 2022

Numer Methods Biomed Eng

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It is important to obtain accurate boundary conditions (BCs) in hemodynamic simulations. This article aimed to improve the accuracy of BCs in computational fluid dynamics (CFD) simulation and analyze the differences in hemodynamics between healthy volunteers and patients with visceral arterial stenosis (VAS). The geometric models of seven cases were reconstructed using the magnetic resonance angiogram (MRA) or computed tomography angiogram (CTA) imaging data. The physiological flow waveforms obtained from 2D Phase Contrast Magnetic Resonance Imaging (PCMRI) were imposed on the aortic inlet and the visceral arteries' outlets. The individualized RCR values of the three-element Windkessel model were imposed on the aortic outlet.CFD simulations were run in the open-source software: svSolver. Two specific time points were selected to compare the hemodynamics of healthy volunteers and patients with VAS. The results suggested that blood in the stenotic visceral arteries flowed at high speed throughout the cardiac cycle. The low pressure is distributed at stenotic lesions. The wall shear stress (WSS) reached 4 Pa near stenotic locations. The low time average wall shear stress (TAWSS), high oscillatory shear index (OSI), and high relative residence time (RRT) concentrated in the abdominal aorta. Besides, the ratios of the areas with low TAWSS, high OSI, and high RRT to the computational domain were higher in patients with VAS than which in the healthy volunteers. The individualized BCs were used for hemodynamic simulations and results suggest that patients with stenosis have a higher risk of blood retention and atherosclerosis formation in the abdominal aorta.

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Stenosis Indicators Applied to Patient-Specific Renal Arteries without and with Stenosis

Cited by 10 publications

References 31 publications

Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

Modeling Blood Pulsatile Turbulent Flow in Stenotic Coronary Arteries

Pulsatile Aortic Blood Flow—A Critical Assessment of Boundary Conditions

Numerical simulation in the abdominal aorta and the visceral arteries with or without stenosis based on 2D PCMRI

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