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Wiśniewski K, Tyfa Z, Reorowicz P, Brandel MG, Adel T, Obidowski D, Jóźwik K, Levy ML. Numerical flow experiment for assessing predictors for cerebrovascular accidents in patients with PHACES syndrome. Sci Rep 2024; 14:5161. [PMID: 38431727 PMCID: PMC10908848 DOI: 10.1038/s41598-024-55345-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 02/22/2024] [Indexed: 03/05/2024] Open
Abstract
There is an increased risk of cerebrovascular accidents (CVA) in individuals with PHACES, yet the precise causes are not well understood. In this analysis, we aimed to examine the role of arteriopathy in PHACES syndrome as a potential contributor to CVA. We analyzed clinical and radiological data from 282 patients with suspected PHACES syndrome. We analyzed clinical features, including the presence of infantile hemangioma and radiological features based on magnetic resonance angiography or computed tomography angiography, in individuals with PHACES syndrome according to the Garzon criteria. To analyze intravascular blood flow, we conducted a simulation based on the Fluid-Structure Interaction (FSI) method, utilizing radiological data. The collected data underwent statistical analysis. Twenty patients with PHACES syndrome were included. CVAs were noted in 6 cases. Hypoplasia (p = 0.03), severe tortuosity (p < 0.01), absence of at least one main cerebral artery (p < 0.01), and presence of persistent arteries (p = 0.01) were associated with CVAs, with severe tortuosity being the strongest predictor. The in-silico analysis showed that the combination of hypoplasia and severe tortuosity resulted in a strongly thrombogenic environment. Severe tortuosity, combined with hypoplasia, is sufficient to create a hemodynamic environment conducive to thrombus formation and should be considered high-risk for cerebrovascular accidents (CVAs) in PHACES patients.
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Affiliation(s)
- Karol Wiśniewski
- Department of Neurosurgery, University of California, San Diego-Rady Children's Hospital, San Diego, CA, 92123, USA.
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Barlicki University Hospital, Kopcińskiego 22, 90-153, Lodz, Poland.
- Institute of Turbomachinery, Lodz University of Technology, 219/223 Wolczanska Str., 90-924, Lodz, Poland.
| | - Zbigniew Tyfa
- Institute of Turbomachinery, Lodz University of Technology, 219/223 Wolczanska Str., 90-924, Lodz, Poland
| | - Piotr Reorowicz
- Institute of Turbomachinery, Lodz University of Technology, 219/223 Wolczanska Str., 90-924, Lodz, Poland
| | - Michael G Brandel
- Department of Neurosurgery, University of California, San Diego-Rady Children's Hospital, San Diego, CA, 92123, USA
| | - Thomas Adel
- Department of Neurosurgery, University of California, San Diego-Rady Children's Hospital, San Diego, CA, 92123, USA
- Medical University of Vienna, Spitalgasse 23 Str., 1090, Wien, Austria
| | - Damian Obidowski
- Institute of Turbomachinery, Lodz University of Technology, 219/223 Wolczanska Str., 90-924, Lodz, Poland
| | - Krzysztof Jóźwik
- Institute of Turbomachinery, Lodz University of Technology, 219/223 Wolczanska Str., 90-924, Lodz, Poland
| | - Michael L Levy
- Department of Neurosurgery, University of California, San Diego-Rady Children's Hospital, San Diego, CA, 92123, USA
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Reorowicz P, Tyfa Z, Obidowski D, Wiśniewski K, Stefańczyk L, Jóźwik K, Levy ML. Blood flow through the fusiform aneurysm treated with the Flow Diverter stent – Numerical investigations. Biocybern Biomed Eng 2022. [DOI: 10.1016/j.bbe.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Wiśniewski K, Tyfa Z, Tomasik B, Reorowicz P, Bobeff EJ, Posmyk BJ, Hupało M, Stefańczyk L, Jóźwik K, Jaskólski DJ. Risk Factors for Recanalization after Coil Embolization. J Pers Med 2021; 11:jpm11080793. [PMID: 34442437 PMCID: PMC8398571 DOI: 10.3390/jpm11080793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/11/2021] [Indexed: 11/19/2022] Open
Abstract
The aim of our study was to identify risk factors for recanalization 6 months after coil embolization using clinical data followed by computational fluid dynamics (CFD) analysis. Methods: Firstly, clinical data of 184 patients treated with coil embolization were analyzed retrospectively. Secondly, aneurysm models for high/low recanalization risk were generated based on ROC curves and their cut-off points. Afterward, CFD was utilized to validate the results. Results: In multivariable analysis, aneurysm filling during the first embolization was an independent risk factor whilst packing density was a protective factor of recanalization after 6 months in patients with aSAH. For patients with unruptured aneurysms, packing density was found to be a protective factor whilst the aneurysm neck size was an independent risk factor. Complex flow pattern and multiple vortices were associated with aneurysm shape and were characteristic of the high recanalization risk group. Conclusions: Statistical analysis suggested that there are various factors influencing recanalization risk. Once certain values of morphometric parameters are exceeded, a complex flow with numerous vortices occurs. This phenomenon was revealed due to CFD investigations that validated our statistical research. Thus, the complex flow pattern itself can be treated as a relevant recanalization predictor.
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Affiliation(s)
- Karol Wiśniewski
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (M.H.); (D.J.J.)
- Correspondence: ; Tel.: +48-042-6776770
| | - Zbigniew Tyfa
- Institute of Turbomachinery, Medical Apparatus Division, Lodz University of Technology, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Bartłomiej Tomasik
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, 15 Mazowiecka St., 92-215 Lodz, Poland;
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Piotr Reorowicz
- Institute of Turbomachinery, Medical Apparatus Division, Lodz University of Technology, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Ernest J. Bobeff
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (M.H.); (D.J.J.)
| | - Bartłomiej J. Posmyk
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (M.H.); (D.J.J.)
| | - Marlena Hupało
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (M.H.); (D.J.J.)
| | - Ludomir Stefańczyk
- Department of Radiology-Diagnostic Imaging, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland;
| | - Krzysztof Jóźwik
- Institute of Turbomachinery, Medical Apparatus Division, Lodz University of Technology, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Dariusz J. Jaskólski
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (M.H.); (D.J.J.)
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Wiśniewski K, Tomasik B, Tyfa Z, Reorowicz P, Bobeff EJ, Stefańczyk L, Posmyk BJ, Jóźwik K, Jaskólski DJ. Porous Media Computational Fluid Dynamics and the Role of the First Coil in the Embolization of Ruptured Intracranial Aneurysms. J Clin Med 2021; 10:jcm10071348. [PMID: 33805169 PMCID: PMC8037793 DOI: 10.3390/jcm10071348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/28/2021] [Accepted: 03/20/2021] [Indexed: 11/22/2022] Open
Abstract
Background: The objective of our project was to identify a late recanalization predictor in ruptured intracranial aneurysms treated with coil embolization. This goal was achieved by means of a statistical analysis followed by a computational fluid dynamics (CFD) with porous media modelling approach. Porous media CFD simulated the hemodynamics within the aneurysmal dome after coiling. Methods: Firstly, a retrospective single center analysis of 66 aneurysmal subarachnoid hemorrhage patients was conducted. The authors assessed morphometric parameters, packing density, first coil volume packing density (1st VPD) and recanalization rate on digital subtraction angiograms (DSA). The effectiveness of initial endovascular treatment was visually determined using the modified Raymond–Roy classification directly after the embolization and in a 6- and 12-month follow-up DSA. In the next step, a comparison between porous media CFD analyses and our statistical results was performed. A geometry used during numerical simulations based on a patient-specific anatomy, where the aneurysm dome was modelled as a separate, porous domain. To evaluate hemodynamic changes, CFD was utilized for a control case (without any porosity) and for a wide range of porosities that resembled 1–30% of VPD. Numerical analyses were performed in Ansys CFX solver. Results: A multivariate analysis showed that 1st VPD affected the late recanalization rate (p < 0.001). Its value was significantly greater in all patients without recanalization (p < 0.001). Receiver operating characteristic curves governed by the univariate analysis showed that the model for late recanalization prediction based on 1st VPD (AUC 0.94 (95%CI: 0.86–1.00) is the most important predictor of late recanalization (p < 0.001). A cut-off point of 10.56% (sensitivity—0.722; specificity—0.979) was confirmed as optimal in a computational fluid dynamics analysis. The CFD results indicate that pressure at the aneurysm wall and residual flow volume (blood volume with mean fluid velocity > 0.01 m/s) within the aneurysmal dome tended to asymptotically decrease when VPD exceeded 10%. Conclusions: High 1st VPD decreases the late recanalization rate in ruptured intracranial aneurysms treated with coil embolization (according to our statistical results > 10.56%). We present an easy intraoperatively calculable predictor which has the potential to be used in clinical practice as a tip to improve clinical outcomes.
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Affiliation(s)
- Karol Wiśniewski
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Barlicki University Hospital, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (D.J.J.)
- Correspondence: ; Tel.: +48-(042)-677-6770
| | - Bartłomiej Tomasik
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, 15 Mazowiecka St., 92-215 Lodz, Poland; or
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Zbigniew Tyfa
- Institute of Turbomachinery, Lodz University of Technology, Medical Apparatus Division, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Piotr Reorowicz
- Institute of Turbomachinery, Lodz University of Technology, Medical Apparatus Division, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Ernest J. Bobeff
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Barlicki University Hospital, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (D.J.J.)
| | - Ludomir Stefańczyk
- Department of Radiology—Diagnostic Imaging, Medical University of Lodz, Kopcińskiego 22, 90-153 Lodz, Poland;
| | - Bartłomiej J. Posmyk
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Barlicki University Hospital, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (D.J.J.)
| | - Krzysztof Jóźwik
- Institute of Turbomachinery, Lodz University of Technology, Medical Apparatus Division, Wolczanska 219/223, 90-924 Lodz, Poland; (Z.T.); (P.R.); (K.J.)
| | - Dariusz J. Jaskólski
- Department of Neurosurgery and Neurooncology, Medical University of Lodz, Barlicki University Hospital, Kopcińskiego 22, 90-153 Lodz, Poland; (E.J.B.); (B.J.P.); (D.J.J.)
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Jodko DM, Obidowski DS, Reorowicz P, JÓŹwik K. A two-stage model of an arteriovenous fistula maturation process. Acta Bioeng Biomech 2020; 22:139-153. [PMID: 32868943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
PURPOSE An arteriovenous fistula has been a widely accepted vascular access for hemodialysis, however, a fistula maturation process is still not fully understood. In the short period of time, right after vein and artery shunting, the physical and biological changes take place mainly in the venous wall. A two-stage modeling method of arteriovenous fistula maturation process was proposed and presented. METHODS The first stage of the maturation was modeled with two-way coupled fluid structure interaction computer simulations. Whereas for the second, biological stage, a model was based on the change in the elasticity of the venous wall due to wall shear stress (WSS) modifications. RESULTS The relation between stress and radial and circumferential strain, based on Lame's theory, makes possible to introduce a mathematical model defining modulus of elasticity, averaged WSS, and venous diameter as time functions. The presented model enables one to predict changes in the monitored parameters in the arteriovenous fistula taking place in the time longer than 90 days. CONCLUSIONS We found that probably the majority of fistulas can be assessed to be mature too early, when the adequate blood flow rate is achieved but mean WSS still remains at the non-physiological level (>10 Pa).
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Affiliation(s)
- Daniel M Jodko
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Damian S Obidowski
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Piotr Reorowicz
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Krzysztof JÓŹwik
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
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Abstract
Purpose: An arteriovenous fistula has been a widely accepted vascular access for hemodialysis, however, a fistula maturation proces is still not fully understood. In the short period of time, right after vein and artery shunting, the physical and biological changes take place mainly in the venous wall. A two-stage modeling method of arteriovenous fistula maturation process was proposed and presented. Methods: The first stage of the maturation was modeled with two-way coupled fluid structure interaction computer simulations. Whereas for the second, biological stage, a model was based on the change in the elasticity of the venous wall due to wall shear stress (WSS) modifications. Results: The relation between stress and radial and circumferential strain, based on Lame’s theory, makes possible to introduce a mathematical model defining modulus of elasticity, averaged WSS, and venous diameter as time functions. The presented model enables one to predict changes in the monitored parameters in the arteriovenous fistula taking place in the time longer than 90 days. Conclusions: We found that probably the majority of fistulas can be assessed to be mature too early, when the adequate blood flow rate is achieved but mean WSS still remains at the non-physiological level (>10 Pa).
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Tyfa Z, Jóźwik P, Obidowski D, Reorowicz P, Jodko D, Kapka K, Makosiej R, Czkwianianc E, Jóźwik K. Inhaled drug airflow patterns and particles deposition in the paediatric respiratory tract. Acta Bioeng Biomech 2020. [DOI: 10.37190/abb-01550-2020-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Purpose: The effectiveness of inhaled drugs is strictly related to areas reachable by drug particles. Unless particles reach the desired part of the bronchial tree, their influence might not meet the expectations. Consequently, the disease progress might not be stopped or even slowed down. Therefore, the primary objective of this research was to analyze the airflow patterns and particle deposition of a standard inhaled drug using computational fluid dynamics. Methods: The study was devoted to the analysis of the particle Diameter influence on their deposition areas within the entire respiratory tract. Two patient-specific respiratory tract models, for 6 and 12-year-old patients, were reconstructed based on the computed tomography examinations. Numerical analyses were carried out as stationary ones with the constant inflow of the particles of various diameters (within the range of 1–50 μm). It was proven that depending on the particle size, their deposition within the respiratory tract varies significantly. Results: The vast majority of the particles with diameters over 20 μm is gathered on the walls of the throat, whereas particles of diameters 5–15 μm are accumulated mainly on the trachea walls, leaving the alveoli insufficiently supplied with the drug particles. Conclusions: The inhaled drug size cannot be treated as negligible factor during the drug spraying. An improper distribution of the particles might not inhibit the symptoms of the asthma. Numerical simulations may improve drugs selection and visualize their distribution along the airways, which might accelerate asthma treatment personalization.
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Tyfa Z, JÓŹwik P, Obidowski D, Reorowicz P, Jodko D, Kapka K, Makosiej R, Czkwianianc E, JÓŹwik K. Inhaled drug airflow patterns and particles deposition in the paediatric respiratory tract. Acta Bioeng Biomech 2020; 22:101-110. [PMID: 32868947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
PURPOSE The effectiveness of inhaled drugs is strictly related to areas reachable by drug particles. Unless particles reach the desired part of the bronchial tree, their influence might not meet the expectations. Consequently, the disease progress might not be stopped or even slowed down. Therefore, the primary objective of this research was to analyze the airflow patterns and particle deposition of a standard inhaled drug using computational fluid dynamics. METHODS The study was devoted to the analysis of the particle diameter influence on their deposition areas within the entire respiratory tract. Two patient-specific respiratory tract models, for 6 and 12-year-old patients, were reconstructed based on the computed tomography examinations. Numerical analyses were carried out as stationary ones with the constant inflow of the particles of various diameters (within the range of 1-50 μm). It was proven that depending on the particle size, their deposition within the respiratory tract varies significantly. RESULTS The vast majority of the particles with diameters over 20 μm is gathered on the walls of the throat, whereas particles of diameters 5-15 μm are accumulated mainly on the trachea walls, leaving the alveoli insufficiently supplied with the drug particles. CONCLUSIONS The inhaled drug size cannot be treated as negligible factor during the drug spraying. An improper distribution of the particles might not inhibit the symptoms of the asthma. Numerical simulations may improve drugs selection and visualize their distribution along the airways, which might accelerate asthma treatment personalization.
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Affiliation(s)
- Zbigniew Tyfa
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Paulina JÓŹwik
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Damian Obidowski
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Piotr Reorowicz
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Daniel Jodko
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
| | - Karolina Kapka
- Department of Gastroenterology, Allergology and Pediatrics, Polish Mother's Memorial Hospital Research Institute, Łódź, Poland
| | - Ryszard Makosiej
- Department of Gastroenterology, Allergology and Pediatrics, Polish Mother's Memorial Hospital Research Institute, Łódź, Poland
| | - ElŻbieta Czkwianianc
- Department of Gastroenterology, Allergology and Pediatrics, Polish Mother's Memorial Hospital Research Institute, Łódź, Poland
| | - Krzysztof JÓŹwik
- Institute of Turbomachinery, Lodz University of Technology, Łódź, Poland
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Abstract
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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Affiliation(s)
- Damian Obidowski
- Division of Medical Apparatus, Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
| | - Piotr Reorowicz
- Division of Medical Apparatus, Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
| | - Dariusz Witkowski
- Division of Medical Apparatus, Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
| | - Krzysztof Sobczak
- Division of Medical Apparatus, Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
| | - Krzysztof Jóźwik
- Division of Medical Apparatus, Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
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Jodko D, Obidowski D, Reorowicz P, Jóźwik K. Blood flows in end-to-end arteriovenous fistulas: Unsteady and steady state numerical investigations of three patient-specific cases. Biocybern Biomed Eng 2017. [DOI: 10.1016/j.bbe.2017.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jodko D, Obidowski D, Reorowicz P, Jóźwik K. Numerical investigations of the unsteady blood flow in the end-to-side arteriovenous fistula for hemodialysis. Acta Bioeng Biomech 2016; 18:3-13. [PMID: 28133372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
PURPOSE The aim of this study was to investigate the blood flow in the end-to-side arteriovenous (a-v) fistula, taking into account its pulsating nature and the patient-specific geometry of blood vessels. Computational Fluid Dynamics (CFD) methods were used for this analysis. METHODS DICOM images of the fistula, obtained from the angio-computed tomography, were a source of the data applied to develop a 3D geometrical model of the fistula. The model was meshed, then the ANSYS CFX v. 15.0 code was used to perform simulations of the flow in the vessels under analysis. Mesh independence tests were conducted. The non-Newtonian rheological model of blood and the Shear Stress Transport model of turbulence were employed. Blood vessel walls were assumed to be rigid. RESULTS Flow patterns, velocity fields, the volume flow rate, the wall shear stress (WSS) propagation on particular blood vessel walls were shown versus time. The maximal value of the blood velocity was identified in the anastomosis - the place where the artery is connected to the vein. The flow rate was calculated for all veins receiving blood. CONCLUSIONS The blood flow in the geometrically complicated a-v fistula was simulated. The values and oscillations of the WSS are the largest in the anastomosis, much lower in the artery and the lowest in the cephalic vein. A strong influence of the mesh on the results concerning the maximal and area-averaged WSS was shown. The relation between simulations of the pulsating and stationary flow under time-averaged flow conditions was presented.
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Affiliation(s)
- Daniel Jodko
- Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland
| | - Damian Obidowski
- Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland
| | - Piotr Reorowicz
- Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland
| | - Krzysztof Jóźwik
- Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland
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Reorowicz P, Obidowski D, Klosinski P, Szubert W, Stefanczyk L, Jozwik K. Numerical simulations of the blood flow in the patient-specific arterial cerebral circle region. J Biomech 2014; 47:1642-51. [DOI: 10.1016/j.jbiomech.2014.02.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 01/28/2014] [Accepted: 02/25/2014] [Indexed: 10/25/2022]
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Jodko D, Obidowski D, Reorowicz P, Jóźwik K. Simulations of the blood flow in the arterio-venous fistula for haemodialysis. Acta Bioeng Biomech 2014; 16:69-74. [PMID: 24708294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The Ciminio-Brescia arterio-venous fistula is a preferred vascular access for haemodialysis, but it is often associated with the development of vascular complications, due to changes in hemodynamic conditions. Computational fluid dynamics methods were involved to carry out seven simulations of the blood flow through the fistula for the patient specific (geometrical) case and various boundary conditions. The geometrical data, obtained from the angio-computed tomography, were used to create a 3-dimensional CAD model of the fistula. The blood flow patterns, blood velocity and the wall shear stress, thought to play a key role in the development of typical complications (stenoses, thromboses, aneurysms, etc.), have been analyzed in this study. The blood flow is reversed locally downstream the anastomosis (where the artery is connected to the vein) and downstream the stenosis in the cannulated vein. Blood velocity reaches abnormal value in the anastomosis during the systolic phase of the cardiac cycle (2.66 m/s). The wall shear stress changes in this place during a single cycle of the heart operation from 27.9 to 71.3 Pa (average 41.5 Pa). The results are compared with data found in the literature.
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Affiliation(s)
- Daniel Jodko
- Łódź University of Technology, Institute of Turbomachinery, Łódź, Poland
| | - Damian Obidowski
- Łódź University of Technology, Institute of Turbomachinery, Łódź, Poland
| | - Piotr Reorowicz
- Łódź University of Technology, Institute of Turbomachinery, Łódź, Poland
| | - Krzysztof Jóźwik
- Łódź University of Technology, Institute of Turbomachinery, Łódź, Poland
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