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Ngwenya T, Grundlingh D, Ngoepe MN. Influence of vortical structures on fibrin clot formation in cerebral aneurysms: A two-dimensional computational study. J Biomech 2024; 165:111994. [PMID: 38394954 DOI: 10.1016/j.jbiomech.2024.111994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 02/09/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024]
Abstract
Thrombosis is an important contributor to cerebral aneurysm growth and progression. A number of sophisticated multiscale and multiphase in silico models have been developed with a view towards interventional planning. Many of these models are able to account for clotting outcomes, but do not provide detailed insight into the role of flow during clot development. In this study, we present idealised, two-dimensional in silico cerebral fibrin clot model based on computational fluid dynamics (CFD), biochemical modelling and variable porosity, permeability, and diffusivity. The model captures fibrin clot growth in cerebral aneurysms over a period at least 1000 s in five different geometries. The fibrin clot growth results were compared to an experiment presented in literature. The biochemistry was found to be more sensitive to mesh size compared to the haemodynamics, while larger timesteps overpredicted clot size in pulsatile flow. When variable diffusivity was used, the predicted clot size was 25.4% lesser than that with constant diffusivity. The predicted clot size in pulsatile flow was 14.6% greater than in plug flow. Different vortex modes were observed in plug and pulsatile flow; the latter presented smaller intermediate modes where the main vortex was smaller and less likely to disrupt the growing fibrin clot. Furthermore, smaller vortex modes were seen to support fibrin clot propagation across geometries. The model clearly demonstrates how the growing fibrin clot alters vortical structures within the aneurysm sac and how this changing flow, in turn, shapes the growing fibrin clot.
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Affiliation(s)
- Tinashe Ngwenya
- Centre for Research in Computational and Applied Mechanics (CERECAM), University of Cape Town, South Africa; Department of Mechanical Engineering, University of Cape Town, South Africa
| | - Divan Grundlingh
- Department of Mechanical Engineering, University of Cape Town, South Africa
| | - Malebogo N Ngoepe
- Centre for Research in Computational and Applied Mechanics (CERECAM), University of Cape Town, South Africa; Department of Mechanical Engineering, University of Cape Town, South Africa.
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Valeti C, Gurusamy S, Krishnakumar K, Easwer HV, Kannath SK, Sudhir BJ, Patnaik BSV. Numerical investigation of unruptured middle cerebral artery bifurcation aneurysms: influence of aspect ratio. Comput Methods Biomech Biomed Engin 2023:1-16. [PMID: 37968912 DOI: 10.1080/10255842.2023.2279508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 10/30/2023] [Indexed: 11/17/2023]
Abstract
An aneurysm is a disease condition, which is due to the pathological weakening of an arterial wall. These aneurysms are often found in various branch points and bifurcations of an artery in the cerebral circulation. Most aneurysms come to medical attention, either due to brain hemorrhages caused by rupture or found unruptured. To consider surgically invasive treatment modalities, clinicians need scientific methods such as, hemodynamic analysis to assess rupture risk. The arterial wall loses its structural integrity when wall shear stress (WSS) and other hemodynamic parameters exceed a certain threshold. In the present study, numerical simulations are carried out for unruptured middle cerebral artery (MCA) aneurysms. Three distinct representative sizes are chosen from a larger patient pool of 26 MCA aneurysms. Logically, these aneurysms represent three growth stages of any patient with similar anatomical structure. Simulations are performed to compare the three growth phases (with different aspect ratios) of an aneurysm and correlate their hemodynamic parameters. Simulations with patient specific boundary conditions reveal that, aneurysms with a higher aspect ratio (AR) correspond to an attendant decrease in both time-averaged wall shear stress (TAWSS) and spatial wall shear stress gradients (WSSG). Smaller MCAs were observed to have higher positive wall shear stress divergence (WSSD), exemplifying the tensile nature of arterial wall stretching. Present study identifies positive wall shear stress divergence (PWSSD) to be a potential biomarker for evaluating the growth of an aneurysm.
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Affiliation(s)
- Chanikya Valeti
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
| | - Saravanan Gurusamy
- Department of Civil, Structural and Environmental Engineering, Trinity College, Dublin, Ireland
| | - K Krishnakumar
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - Hariharan Venkat Easwer
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - Santhosh K Kannath
- Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - B J Sudhir
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
- Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
| | - B S V Patnaik
- Department of Applied Mechanics and Biomedical Engineering, IIT Madras, Chennai, India
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Shimano K, Serigano S, Ikeda N, Yuchi T, Shiratori S, Nagano H. Understanding of boundary conditions imposed at multiple outlets in computational haemodynamic analysis of cerebral aneurysm. ACTA ACUST UNITED AC 2019. [DOI: 10.17106/jbr.33.32] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Kenjiro Shimano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Shota Serigano
- Graduate School of Integrative Science and Engineering, Tokyo City University
| | - Naoki Ikeda
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Tomoki Yuchi
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Suguru Shiratori
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
| | - Hideaki Nagano
- Department of Mechanical Systems Engineering, Faculty of Engineering, Tokyo City University
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Owen B, Bojdo N, Jivkov A, Keavney B, Revell A. Structural modelling of the cardiovascular system. Biomech Model Mechanobiol 2018; 17:1217-1242. [PMID: 29911296 PMCID: PMC6154127 DOI: 10.1007/s10237-018-1024-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 04/25/2018] [Indexed: 02/02/2023]
Abstract
Computational modelling of the cardiovascular system offers much promise, but represents a truly interdisciplinary challenge, requiring knowledge of physiology, mechanics of materials, fluid dynamics and biochemistry. This paper aims to provide a summary of the recent advances in cardiovascular structural modelling, including the numerical methods, main constitutive models and modelling procedures developed to represent cardiovascular structures and pathologies across a broad range of length and timescales; serving as an accessible point of reference to newcomers to the field. The class of so-called hyperelastic materials provides the theoretical foundation for the modelling of how these materials deform under load, and so an overview of these models is provided; comparing classical to application-specific phenomenological models. The physiology is split into components and pathologies of the cardiovascular system and linked back to constitutive modelling developments, identifying current state of the art in modelling procedures from both clinical and engineering sources. Models which have originally been derived for one application and scale are shown to be used for an increasing range and for similar applications. The trend for such approaches is discussed in the context of increasing availability of high performance computing resources, where in some cases computer hardware can impact the choice of modelling approach used.
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Affiliation(s)
- Benjamin Owen
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK.
| | - Nicholas Bojdo
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
| | - Andrey Jivkov
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
| | - Bernard Keavney
- Division of Cardiovascular Sciences, University of Manchester, AV Hill Building, Manchester, M13 9PT, UK
| | - Alistair Revell
- School of Mechanical, Aerospace and Civil Engineering, University of Manchester, George Begg Building, Manchester, M1 3BB, UK
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Ogawa Y, Nakahara T, Nishida Y, Kobayashi C, Hirata T, Nagano H, Shiratori S, Shimano K. In vitro measurement of platelet adhesion to intact endothelial cells under low shear conditions. Biorheology 2018; 54:51-65. [PMID: 29355112 DOI: 10.3233/bir-17139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Prediction of thrombus formation at intact arterial walls under low shear flow conditions is clinically important particularly for better prognoses of embolisation in cerebral aneurysms. Although a new mathematical model for this purpose is necessary, little quantitative information has been known about platelet adhesion to intact endothelial cells. OBJECTIVE The objective of this study is to measure the number of platelets adhering to intact endothelial cells with a focus upon the influence of the shear rate. METHODS Endothelial cells disseminated in μ-slides were exposed to swine whole blood at different shear rates. Adenosine diphosphate (ADP) was used as an agonist. Adherent platelets were counted by means of scanning electron microscopy. RESULTS At an ADP concentration of 1 µM, 20.8 ± 3.1 platelets per 900 µm2 were observed after 30-minute perfusion at a shear rate of 0.8 s-1 whereas only 3.0 ± 1.4 per 900 µm2 at 16.8 s-1. CONCLUSIONS The number of adherent platelets is determined by a balance between the shear and the degree of stimulation by the agonist. At an ADP concentration of 1 µM, a limit to the shear rate at which platelets can adhere to intact endothelial cells is considered to be slightly higher than 16.8 s-1.
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Affiliation(s)
- Yuki Ogawa
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
| | - Takuma Nakahara
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
| | - Yuma Nishida
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
| | - Chihiro Kobayashi
- Department of Medical Engineering, Tokyo City University, Tokyo, Japan
| | - Takamichi Hirata
- Department of Medical Engineering, Tokyo City University, Tokyo, Japan
| | - Hideaki Nagano
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
| | - Suguru Shiratori
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
| | - Kenjiro Shimano
- Department of Mechanical Systems Engineering, Tokyo City University, Tokyo, Japan
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Sindeev S, Arnold PG, Frolov S, Prothmann S, Liepsch D, Balasso A, Berg P, Kaczmarz S, Kirschke JS. Phase-contrast MRI versus numerical simulation to quantify hemodynamical changes in cerebral aneurysms after flow diverter treatment. PLoS One 2018; 13:e0190696. [PMID: 29304062 PMCID: PMC5755883 DOI: 10.1371/journal.pone.0190696] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 12/19/2017] [Indexed: 02/05/2023] Open
Abstract
Cerebral aneurysms are a major risk factor for intracranial bleeding with devastating consequences for the patient. One recently established treatment is the implantation of flow-diverters (FD). Methods to predict their treatment success before or directly after implantation are not well investigated yet. The aim of this work was to quantitatively study hemodynamic parameters in patient-specific models of treated cerebral aneurysms and its correlation with the clinical outcome. Hemodynamics were evaluated using both computational fluid dynamics (CFD) and phase contrast (PC) MRI. CFD simulations and in vitro MRI measurements were done under similar flow conditions and results of both methods were comparatively analyzed. For preoperative and postoperative distribution of hemodynamic parameters, CFD simulations and PC-MRI velocity measurements showed similar results. In both cases where no occlusion of the aneurysm was observed after six months, a flow reduction of about 30-50% was found, while in the clinically successful case with complete occlusion of the aneurysm after 6 months, the flow reduction was about 80%. No vortex was observed in any of the three models after treatment. The results are in agreement with recent studies suggesting that CFD simulations can predict post-treatment aneurysm flow alteration already before implantation of a FD and PC-MRI could validate the predicted hemodynamic changes right after implantation of a FD.
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Affiliation(s)
- Sergey Sindeev
- Department of Biomedical Engineering, Tambov State Technical University, Tambov, Russia
- * E-mail:
| | - Philipp Georg Arnold
- Department of Neuroradiology, Klinikum rechts der Isar of Technical University of Munich, Munich, Germany
| | - Sergey Frolov
- Department of Biomedical Engineering, Tambov State Technical University, Tambov, Russia
| | - Sascha Prothmann
- Department of Neuroradiology, Klinikum rechts der Isar of Technical University of Munich, Munich, Germany
| | - Dieter Liepsch
- Department of Building Services Engineering, Chemical Engineering for Paper and Packaging, Print and Media Technologies, Munich University of Applied Sciences, Munich, Germany
| | - Andrea Balasso
- Department of Earth and Environmental Sciences, Ludwig-Maximilian-University of Munich, Munich, Germany
| | - Philipp Berg
- Department of Fluid Dynamics and Technical Flows, University of Magdeburg, Magdeburg, Germany
| | - Stephan Kaczmarz
- Department of Neuroradiology, Klinikum rechts der Isar of Technical University of Munich, Munich, Germany
| | - Jan Stefan Kirschke
- Department of Neuroradiology, Klinikum rechts der Isar of Technical University of Munich, Munich, Germany
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Frolov SV, Sindeev SV, Liepsch D, Balasso A. Experimental and CFD flow studies in an intracranial aneurysm model with Newtonian and non-Newtonian fluids. Technol Health Care 2017; 24:317-33. [PMID: 26835725 DOI: 10.3233/thc-161132] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND According to the clinical data, flow conditions play a major role in the genesis of intracranial aneurysms. The disorder of the flow structure is the cause of damage of the inner layer of the vessel wall, which leads to the development of cerebral aneurysms. Knowledge of the alteration of the flow field in the aneurysm region is important for treatment. OBJECTIVE The aim is to study quantitatively the flow structure in an patient-specific aneurysm model of the internal carotid artery using both experimental and computational fluid dynamics (CFD) methods with Newtonian and non-Newtonian fluids. METHODS A patient-specific geometry of aneurysm of the internal carotid artery was used. Patient data was segmented and smoothed to obtain geometrical model. An elastic true-to-scale silicone model was created with stereolithography. For initial investigation of the blood flow, the flow was visualized by adding particles into the silicone model. The precise flow velocity measurements were done using 1D Laser Doppler Anemometer with a spatial resolution of 50 μ m and a temporal resolution of 1 ms. The local velocity measurements were done at a distance of 4 mm to each other. A fluid with non-Newtonian properties was used in the experiment. The CFD simulations for unsteady-state problem were done using constructed hexahedral mesh for Newtonian and non-Newtonian fluids. RESULTS Using 1D laser Doppler Anemometer the minimum velocity magnitude at the end of systole -0.01 m/s was obtained in the aneurysm dome while the maximum velocity 1 m/s was at the center of the outlet segment. On central cross section of the aneurysm the maximum velocity value is only 20% of the average inlet velocity. The average velocity on the cross-section is only 11% of the inlet axial velocity. Using the CFD simulation the wall shear stresses for Newtonian and non-Newtonian fluid at the end of systolic phase (t= 0.25 s) were computed. The wall shear stress varies from 3.52 mPa (minimum value) to 10.21 Pa (maximum value) for the Newtonian fluid. For the non-Newtonian fluid the wall shear stress minimum is 2.94 mPa; the maximum is 9.14 Pa. The lowest value of the wall shear stress for both fluids was obtained at the dome of the aneurysm while the highest wall shear stress was at the beginning of the outlet segment. The vortex in the aneurysm region is unstable during the cardiac cycle. The clockwise rotation of the streamlines at the inlet segment for Newtonian and non-Newtonian fluid is shown. CONCLUSION The results of the present study are in agreement with the hemodynamics theory of aneurysm genesis. Low value of wall shear stress is observed at the aneurysm dome which can cause a rupture of an aneurysm.
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Affiliation(s)
- S V Frolov
- Department of Biomedical Engineering, Tambov State Technical University, Tambov, Russia
| | - S V Sindeev
- Department of Biomedical Engineering, Tambov State Technical University, Tambov, Russia
| | - D Liepsch
- Department of Mechanical Engineering, Munich University of Applied Sciences, Munich, Germany
| | - A Balasso
- Department of Neuroradiology, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
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Castro MA. Understanding the role of hemodynamics in the initiation, progression, rupture, and treatment outcome of cerebral aneurysm from medical image-based computational studies. ISRN RADIOLOGY 2013; 2013:602707. [PMID: 24967285 PMCID: PMC4045510 DOI: 10.5402/2013/602707] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/19/2013] [Indexed: 12/31/2022]
Abstract
About a decade ago, the first image-based computational hemodynamic studies of cerebral aneurysms were presented. Their potential for clinical applications was the result of a right combination of medical image processing, vascular reconstruction, and grid generation techniques used to reconstruct personalized domains for computational fluid and solid dynamics solvers and data analysis and visualization techniques. A considerable number of studies have captivated the attention of clinicians, neurosurgeons, and neuroradiologists, who realized the ability of those tools to help in understanding the role played by hemodynamics in the natural history and management of intracranial aneurysms. This paper intends to summarize the most relevant results in the field reported during the last years.
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Affiliation(s)
- Marcelo A. Castro
- Grupo de Investigación y Desarrollo en Bioingeniería, Facultad Regional Buenos Aires, Universidad Tecnológica Nacional, CONICET, Medrano 951, CP 1179, Buenos Aires, Argentina
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Zhang Y, Chong W, Qian Y. Investigation of intracranial aneurysm hemodynamics following flow diverter stent treatment. Med Eng Phys 2013; 35:608-15. [DOI: 10.1016/j.medengphy.2012.07.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 07/16/2012] [Accepted: 07/16/2012] [Indexed: 11/29/2022]
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