Blood flows in end-to-end arteriovenous fistulas: Unsteady and steady state numerical investigations of three patient-specific cases

Jodko, D.; Obidowski, D.; Reorowicz, P.; Jóźwik, Krzysztof

doi:10.1016/j.bbe.2017.05.006

Cited by 17 publications

(9 citation statements)

References 29 publications

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“…All the presented stationary and non‐stationary simulations were carried out with the use of the unstructured hybrid tetrahedral grid generated in the fluid domain. The mesh was selected in the mesh independence test based on the grid convergence index (GCI) that was shown in 38 and successfully employed in other numerical studies of blood flows 39,40 . Following the GCI procedure, three meshes containing N 1 , N 2 , and N 3 finite volumes ( N 1 > N 2 > N 3 ) were generated and tested with a rigid‐wall approach for peak systolic conditions.…”

Section: Methodsmentioning

confidence: 99%

“…The mesh was selected in the mesh independence test based on the grid convergence index (GCI) that was shown in 38 and successfully employed in other numerical studies of blood flows. 39,40 Following the GCI procedure, three meshes containing N 1 , N 2 , and N 3 finite volumes (N 1 > N 2 > N 3 ) were generated and tested with a rigid-wall approach for peak systolic conditions. To carry out sensitive flow analyses, on the base of the earlier experience, the mesh generation was started from highly precise mesh containing 20 sublayers (N 1 ) built in the inflation near-wall layer.…”

Section: Mesh and Gcimentioning

confidence: 99%

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Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

Jodko

Jeckowski

Tyfa

2022

Numer Methods Biomed Eng

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The purpose of this paper is to demonstrate the importance of a compliant wall approach in modeling of non‐Newtonian and non‐physiological blood flows. A case study of a stenosed and symptomatic carotid bifurcation was considered to show the influence of the wall‐resilience assumption on the flow parameters obtained with numerical simulations. Patient‐specific data concerning the geometry and flow conditions were collected and used to carry out two‐way coupled fluid structure interaction simulations of the pulsatile blood flow through carotid artery. The wall compliance was considered separately as related to the wall‐elasticity and as associated with the reaction of the loose connective tissue surrounding the carotid bifurcation. The obtained hemodynamic parameters were compared to those which were found in rigid‐wall simulations. The difference between the results obtained for rigid‐wall and compliant‐wall approaches for the peak‐systolic area‐averaged wall shear stress achieved 35%, whereas the difference between the time‐averaged local vorticity and shear strain reached, respectively, 42% and 43%. The influence of the highly resilient wall on the monitored hemodynamic parameters was significant even if time‐averaged values are compared, which suggests that these metrics are considerably overestimated if the wall compliance is not considered. Moreover, the findings show that the mechanical response of the loose connective tissue cannot be neglected in blood flow simulations. Additionally, this study indicates that stiffening of the arterial wall due to atherosclerosis significantly rises hemodynamic parameters. This explains the therapeutic benefits of surgical removal of plaque lesions formed in the carotid bifurcation (endarterectomy).

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Section: Methodsmentioning

confidence: 99%

Section: Mesh and Gcimentioning

confidence: 99%

Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

Jodko

Jeckowski

Tyfa

2022

Numer Methods Biomed Eng

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“…The shear stress transport (SST) turbulence model, which is widely used and proved its quality in many different applications, especially for low Reynolds number flows as in this case, was applied. 17 , 38 – 40 Due to very limited temperature changes, the flow was considered to be isothermal.…”

Section: Methodsmentioning

confidence: 99%

Methods for determination of stagnation in pneumatic ventricular assist devices

et al. 2018

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Background:A pneumatic paediatric ventricular assist device developed at the Foundation of Cardiac Surgery Development, Zabrze, equipped with valves based on J. Moll’s design, with later modifications introduced at the Institute of Turbomachinery, Lodz University of Technology, was tested numerically and experimentally. The main aim of those investigations was to detect stagnation zones within the ventricular assist device and indicate advantages and limitations of both approaches.Methods:In the numerical transient test, a motion of the diaphragm and discs was simulated. Two different methods were used to illustrate stagnation zones in the ventricular assist device. The flow pattern inside the chamber was represented by velocity contours and vectors to validate the results using images obtained in the laser particle image velocimetry experiment.Results:The experimental light-based method implied problems with proper illumination of regions in the wall vicinity. High-resolution flow data and other important parameters as stagnation regions or flow patterns in regions not accessible for light in the particle image velocimetry method are derived in the numerical solution. However, computations of a single case are much more time-consuming if compared to a single experiment conducted on a well-calibrated stand.Conclusion:The resulting main vortexes in the central part of the pump chamber and the velocity magnitudes are correlated in both methods, which are complementary and when used together offer better insight into the flow structure inside the ventricular assist device and enable a deeper analysis of the results.

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“…Depending on the type of problem analyzed, blood maybe reconstructed as Newtonian or non-Newtonian [23]. Such approach enables assessment of the diseases severity and improves planning of the reconstructive surgery [24]. Moreover, application of computational methods allows considering of different mechanical and fluid parameters, e.g., wall shear stress (WSS) [25].…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics as an Engineering Tool for the Reconstruction of Endovascular Prosthesis Endoleaks

et al. 2022

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Background and objectives: Endovascular prosthesis placement is a predominant surgical procedure to reduce the risk of aneurysm rupture in abdominal aortic aneurysm patients. The formation of an endoleak is a major complication of stent-graft placement. Therefore, the aim of this study was to determine the influence of stent-graft's spatial configuration on the risk of leakage under realistic flow conditions. Materials and Methods: We analyzed data collected from 10 male patients 55±3 years old after CTA who had undergone endovascular treatment. Computational Fluid Dynamics technique was applied for the reconstruction of blood hemodynamic. Two cases of the stent-graft were analyzed each time, with and without the endoleak, reconstructed from one patient data with the endoleak. Endoleak-free geometries were prepared by virtual closure of the opening. Results: It was observed that high value of the blood velocity around the endoleak may provoke its slowly rupture, which may increase the blood flow to the aneurysm sack in the case of type II endoleaks. Moreover, the appearance of endoleak reduces the average blood velocity in the entire stent-graft which in some cases may contribute to blood coagulation. Furthermore, no clot can form at the site of the endoleak due to the high value of wall shear stress near of the endoleak which prevents thrombosis.

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Blood flows in end-to-end arteriovenous fistulas: Unsteady and steady state numerical investigations of three patient-specific cases

Cited by 17 publications

References 29 publications

Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

Methods for determination of stagnation in pneumatic ventricular assist devices

Computational Fluid Dynamics as an Engineering Tool for the Reconstruction of Endovascular Prosthesis Endoleaks

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