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Vuong TNAM, Bartolf‐Kopp M, Andelovic K, Jungst T, Farbehi N, Wise SG, Hayward C, Stevens MC, Rnjak‐Kovacina J. Integrating Computational and Biological Hemodynamic Approaches to Improve Modeling of Atherosclerotic Arteries. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307627. [PMID: 38704690 PMCID: PMC11234431 DOI: 10.1002/advs.202307627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 03/12/2024] [Indexed: 05/07/2024]
Abstract
Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.
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Affiliation(s)
| | - Michael Bartolf‐Kopp
- Department of Functional Materials in Medicine and DentistryInstitute of Functional Materials and Biofabrication (IFB)KeyLab Polymers for Medicine of the Bavarian Polymer Institute (BPI)University of WürzburgPleicherwall 297070WürzburgGermany
| | - Kristina Andelovic
- Department of Functional Materials in Medicine and DentistryInstitute of Functional Materials and Biofabrication (IFB)KeyLab Polymers for Medicine of the Bavarian Polymer Institute (BPI)University of WürzburgPleicherwall 297070WürzburgGermany
| | - Tomasz Jungst
- Department of Functional Materials in Medicine and DentistryInstitute of Functional Materials and Biofabrication (IFB)KeyLab Polymers for Medicine of the Bavarian Polymer Institute (BPI)University of WürzburgPleicherwall 297070WürzburgGermany
- Department of Orthopedics, Regenerative Medicine Center UtrechtUniversity Medical Center UtrechtUtrecht3584Netherlands
| | - Nona Farbehi
- Graduate School of Biomedical EngineeringUniversity of New South WalesSydney2052Australia
- Tyree Institute of Health EngineeringUniversity of New South WalesSydneyNSW2052Australia
- Garvan Weizmann Center for Cellular GenomicsGarvan Institute of Medical ResearchSydneyNSW2010Australia
| | - Steven G. Wise
- School of Medical SciencesUniversity of SydneySydneyNSW2006Australia
| | - Christopher Hayward
- St Vincent's HospitalSydneyVictor Chang Cardiac Research InstituteSydney2010Australia
| | | | - Jelena Rnjak‐Kovacina
- Graduate School of Biomedical EngineeringUniversity of New South WalesSydney2052Australia
- Tyree Institute of Health EngineeringUniversity of New South WalesSydneyNSW2052Australia
- Australian Centre for NanoMedicine (ACN)University of New South WalesSydneyNSW2052Australia
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Rahaman M, Paikaray B, Islam M, Mondal S, Moharana J, Pandiaraj S, Periyasami G, Giri R. Simultaneous Effect of EBR on LLDPE and PDMS Rubber Blends and Its Nanocomposites for Cable Applications. ACS OMEGA 2024; 9:828-836. [PMID: 38222534 PMCID: PMC10785612 DOI: 10.1021/acsomega.3c06766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 11/22/2023] [Accepted: 12/13/2023] [Indexed: 01/16/2024]
Abstract
The impact of electron beam radiation on the blend of linear low-density polyethylene (LLDPE) and polydimethylsiloxane (PDMS) rubber at different doses from 50 to 300 kGy has been investigated. The irradiated sheets were examined for their morphology, gel content, thermal stability, melt behavior, and electrical and dielectric properties. The radiation treatment has reduced both the melting point and crystallinity of base polymers and their blends because of chain scission. As observed, 100 kGy doses of irradiated blend and 3 wt % of loaded nanosilica composite showed comparatively good thermal stability. The phase morphology of the LLDPE: PDMS rubber blend showed a honeycomb-like design before irradiation because of two-stage morphology, which prominently changed into a solitary stage after electron beam irradiation. This is because of intermolecular cross-link arrangement inside the singular parts, just like cross-linking development at the interface. From the AQFESEM study, it is observed that the stacking of nanosilica particles within the blend matrix is greatly reduced after electron beam irradiation. The addition of nanosilica within the blend increased the electrical conductivity and dielectric permittivity. The dielectric breakdown strength has been observed to be the highest for 3 wt % loaded nanocomposite and its irradiated sample. The result indicates that the nanocomposite can be utilized for high-voltage cable applications in indoor and outdoor fields.
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Affiliation(s)
- Mostafizur Rahaman
- Department
of Chemistry, College of Science, King Saud
University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Bibhudatta Paikaray
- Department
of Electrical Engineering, GITA Autonomous
College, Bhubaneswar, Odisha 752054, India
| | - Mobasserul Islam
- Department
of Manufacturing Engineering, School of Mechanical Engineering, Vellore Institute of Technology, Vellore 632014, India
| | - Subhadip Mondal
- Department
of Polymer-Nano Science and Technology, Jeonbuk National University, Jeonju 54896, South Korea
| | | | - Saravanan Pandiaraj
- Department
of Physics, College of Science, King Saud
University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Govindasami Periyasami
- Department
of Chemistry, College of Science, King Saud
University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Radhashyam Giri
- Department
of Plastics Technology, CIPET: Institute
of Petrochemicals Technology, Chennai, Tamilnadu 600032, India
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Sonmez F, Karagoz S, Yildirim O, Firat I. Experimental and numerical investigation of the stenosed coronary artery taken from the clinical setting and modeled in terms of hemodynamics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2024; 40:e3793. [PMID: 37975163 DOI: 10.1002/cnm.3793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/31/2023] [Accepted: 11/05/2023] [Indexed: 11/19/2023]
Abstract
The study was carried out to investigate the effect of the artery with different pulse values and stenosis rates on the pressure drop, the peristaltic pump outlet pressure, fractional flow reserve (FFR) and most importantly the amount of power consumed by the peristaltic pump. For this purpose, images taken from the clinical environment were produced as models (10 mm inlet diameter) with 0% and 70% percent areal stenosis rates (PSR) on a three-dimensional (3D) printer. In the experimental system, pure water was used as the fluid at 54, 84, 114, 132, and 168 bpm pulse values. In addition, computational fluid dynamics (CFD) analyzes of the test region were performed using experimental boundary conditions with the help of ANSYS-Fluent software. The findings showed that as PSR increases in the arteries, the pressure drop in the stenosis region increases and this amount increases dramatically with increasing effort. An increase of approximately 40% was observed in the pump outlet pressure value from 54 bpm to 168 bpm in the PSR 0% model and 51% increase in the PSR 70% model. It has been observed that the pump does more work to overcome the increased pressure difference due to increased pulse rate and PSR. With the effect of contraction, the power consumption of the pump increased from 9.2% for 54 bpm to 13.8% for 168 bpm. In both models, the Wall Shear Stress (WSS) increased significantly. WSS increased abruptly in the stenosis and arcuate regions, while sudden decreases were observed in the flow separation region.
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Affiliation(s)
- Fatin Sonmez
- Artvin Vocational School, Artvin Coruh University, Artvin, Turkey
| | - Sendogan Karagoz
- Department of Mechanical Engineering, Ataturk University, Erzurum, Turkey
| | - Orhan Yildirim
- Department of Mechanical Engineering, Ataturk University, Erzurum, Turkey
| | - Ilker Firat
- Ilic Dursun Yildirim Vocational School, Erzincan Binali Yildirim University, Erzincan, Turkey
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Bai X, Fu M, Li Z, Gao P, Zhao H, Li R, Sui B. Distribution and regional variation of wall shear stress in the curved middle cerebral artery using four-dimensional flow magnetic resonance imaging. Quant Imaging Med Surg 2022; 12:5462-5473. [PMID: 36465823 PMCID: PMC9703110 DOI: 10.21037/qims-22-67] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 08/30/2022] [Indexed: 12/05/2023]
Abstract
BACKGROUND To investigate the distribution and regional variation of wall shear stress (WSS) in the curved middle cerebral artery (MCA) in healthy individuals using four-dimensional (4D) flow magnetic resonance imaging (MRI). METHODS A total of 44 healthy participants (18 males; mean ages: 27.16±5.69 years) were included in this cross-sectional study. The WSS parameters of mean, minimum, and maximum values, the coefficient of variation of time-averaged WSS (TAWSSCV), and the maximum values of the oscillatory shear index (OSI) were calculated and compared in the curved proximal (M1) segments. Three cross-sectional planes were selected: the location perpendicular to the beginning of the long axis of the curved M1 segment of the MCA (proximal section), the most curved M1 location (curved M1 section), and the location before the insular (M2) segment bifurcation (distal section). The WSS and OSI parameters of the proximal, curved, and distal sections of the curved M1 segment were compared, including the inner and outer curvatures of the curved M1 section. RESULTS Of the curved M1 segments, the curved M1 section had significantly lower minimum TAWSS values than the proximal (P=0.031) and distal sections (P=0.002), and the curved M1 section had significantly higher maximum OSI values than the distal section (P=0.001). The TAWSSCV values at the curved M1 section were significantly higher than the proximal (P=0.001) and distal sections (P<0.001). At the curved M1 section, the inner curvature showed a significantly lower minimum TAWSS (P=0.013) and higher maximum OSI values (P=0.002) than the outer curvature. CONCLUSIONS There are distribution variation of WSS and OSI parameters at the curved M1 section of the curved MCA, and the inner curvature of the curved M1 section has the lowest WSS and highest OSI distribution. The local hemodynamic features of the curved MCA may be related to the predilection for atherosclerotic plaque development.
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Affiliation(s)
- Xiaoyan Bai
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Mingzhu Fu
- Center for Biomedical Imaging Research, Biomedical Engineering Department, School of Medicine, Tsinghua University, Beijing, China
| | - Zhiye Li
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
- Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Peiyi Gao
- Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Haiqing Zhao
- Department of Radiology, Beijing Chui Yang Liu Hospital, Beijing, China
| | - Rui Li
- Center for Biomedical Imaging Research, Biomedical Engineering Department, School of Medicine, Tsinghua University, Beijing, China
| | - Binbin Sui
- Tiantan Neuroimaging Center of Excellence, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- China National Clinical Research Center for Neurological Diseases, Beijing, China
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Organ-on-a-Chip: Design and Simulation of Various Microfluidic Channel Geometries for the Influence of Fluid Dynamic Parameters. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12083829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Shear stress, pressure, and flow rate are fluid dynamic parameters that can lead to changes in the morphology, proliferation, function, and survival of many cell types and have a determinant impact on tissue function and viability. Microfluidic devices are promising tools to investigate these parameters and fluid behaviour within different microchannel geometries. This study discusses and analyses different designed microfluidic channel geometries regarding the influence of fluid dynamic parameters on their microenvironment at specified fluidic parameters. The results demonstrate that in the circular microchamber, the velocity and shear stress profiles assume a parabolic shape with a maximum velocity occurring in the centre of the chamber and a minimum velocity at the walls. The longitudinal microchannel shows a uniform velocity and shear stress profile throughout the microchannel. Simulation studies for the two geometries with three parallel microchannels showed that in proximity to the micropillars, the velocity and shear stress profiles decreased. Moreover, the pressure is inversely proportional to the width and directly proportional to the flow rate within the microfluidic channels. The simulations showed that the velocity and wall shear stress indicated different values at different flow rates. It was also found that the width and height of the microfluidic channels could affect both velocity and shear stress profiles, contributing to the control of shear stress. The study has demonstrated strategies to predict and control the effects of these forces and the potential as an alternative to conventional cell culture as well as to recapitulate the cell- and organ-specific microenvironment.
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Hydrophobic Recovery of PDMS Surfaces in Contact with Hydrophilic Entities: Relevance to Biomedical Devices. MATERIALS 2022; 15:ma15062313. [PMID: 35329765 PMCID: PMC8950181 DOI: 10.3390/ma15062313] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/08/2022] [Accepted: 03/16/2022] [Indexed: 11/30/2022]
Abstract
Polydimethylsiloxane (PDMS), a silicone elastomer, is increasingly being used in health and biomedical fields due to its excellent optical and mechanical properties. Its biocompatibility and resistance to biodegradation led to various applications (e.g., lung on a chip replicating blood flow, medical interventions, and diagnostics). The many advantages of PDMS are, however, partially offset by its inherent hydrophobicity, which makes it unsuitable for applications needing wetting, thus requiring the hydrophilization of its surface by exposure to UV or O2 plasma. Yet, the elastomeric state of PDMS translates in a slow, hours to days, process of reducing its surface hydrophilicity—a process denominated as hydrophobic recovery. Using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), the present study details the dynamics of hydrophobic recovery of PDMS, on flat bare surfaces and on surfaces embedded with hydrophilic beads. It was found that a thin, stiff, hydrophilic, silica film formed on top of the PDMS material, following its hydrophilization by UV radiation. The hydrophobic recovery of bare PDMS material is the result of an overlap of various nano-mechanical, and diffusional processes, each with its own dynamics rate, which were analyzed in parallel. The hydrophobic recovery presents a hysteresis, with surface hydrophobicity recovering only partially due to a thin, but resilient top silica layer. The monitoring of hydrophobic recovery of PDMS embedded with hydrophilic beads revealed that this is delayed, and then totally stalled in the few-micrometer vicinity of the embedded hydrophilic beads. This region where the hydrophobic recovery stalls can be used as a good approximation of the depth of the resilient, moderately hydrophilic top layer on the PDMS material. The complex processes of hydrophilization and subsequent hydrophobic recovery impact the design, fabrication, and operation of PDMS materials and devices used for diagnostics and medical procedures. Consequently, especially considering the emergence of new surgical procedures using elastomers, the impact of hydrophobic recovery on the surface of PDMS warrants more comprehensive studies.
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7
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Fluid Flow and Structural Numerical Analysis of a Cerebral Aneurysm Model. FLUIDS 2022. [DOI: 10.3390/fluids7030100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Intracranial aneurysms (IA) are dilations of the cerebral arteries and, in most cases, have no symptoms. However, it is a very serious pathology, with a high mortality rate after rupture. Several studies have been focused only on the hemodynamics of the flow within the IA. However, besides the effect of the flow, the development and rupture of the IA are also associated with a combination of other factors such as the wall mechanical behavior. Thus, the objective of this work was to analyze, in addition to the flow behavior, the biomechanical behavior of the aneurysm wall. For this, CFD simulations were performed for different Reynolds numbers (1, 100, 500 and 1000) and for two different rheological models (Newtonian and Carreau). Subsequently, the pressure values of the fluid simulations were exported to the structural simulations in order to qualitatively observe the deformations, strains, normal stresses and shear stress generated in the channel wall. For the structural simulations, a hyperelastic constitutive model (5-parameter Mooney–Rivlin) was used. The results show that with the increase in the Reynolds number (Re), the recirculation phenomenon is more pronounced, which is not seen for Re = 1. The higher the Re, the higher the strain, displacement, normal and shear stresses values.
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8
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Miranda I, Souza A, Sousa P, Ribeiro J, Castanheira EMS, Lima R, Minas G. Properties and Applications of PDMS for Biomedical Engineering: A Review. J Funct Biomater 2021; 13:2. [PMID: 35076525 PMCID: PMC8788510 DOI: 10.3390/jfb13010002] [Citation(s) in RCA: 135] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/13/2021] [Accepted: 12/16/2021] [Indexed: 12/14/2022] Open
Abstract
Polydimethylsiloxane (PDMS) is an elastomer with excellent optical, electrical and mechanical properties, which makes it well-suited for several engineering applications. Due to its biocompatibility, PDMS is widely used for biomedical purposes. This widespread use has also led to the massification of the soft-lithography technique, introduced for facilitating the rapid prototyping of micro and nanostructures using elastomeric materials, most notably PDMS. This technique has allowed advances in microfluidic, electronic and biomedical fields. In this review, an overview of the properties of PDMS and some of its commonly used treatments, aiming at the suitability to those fields' needs, are presented. Applications such as microchips in the biomedical field, replication of cardiovascular flow and medical implants are also reviewed.
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Affiliation(s)
- Inês Miranda
- Center for MicroElectromechanical Systems (CMEMS-UMinho), Campus de Azurém, University of Minho, 4800-058 Guimaraes, Portugal; (I.M.); (P.S.); (G.M.)
| | - Andrews Souza
- MEtRICs, Mechanical Engineering Department, Campus de Azurém, University of Minho, 4800-058 Guimaraes, Portugal;
| | - Paulo Sousa
- Center for MicroElectromechanical Systems (CMEMS-UMinho), Campus de Azurém, University of Minho, 4800-058 Guimaraes, Portugal; (I.M.); (P.S.); (G.M.)
| | - João Ribeiro
- Centro de Investigação de Montanha (CIMO), Campus de Santa Apolónia, Instituto Politécnico de Bragança, 5300-253 Braganca, Portugal;
| | - Elisabete M. S. Castanheira
- Centre of Physics of Minho and Porto Universities (CF-UM-UP), Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal;
| | - Rui Lima
- MEtRICs, Mechanical Engineering Department, Campus de Azurém, University of Minho, 4800-058 Guimaraes, Portugal;
- CEFT, Faculdade de Engenharia da Universidade do Porto (FEUP), Rua Roberto Frias, 4200-465 Porto, Portugal
| | - Graça Minas
- Center for MicroElectromechanical Systems (CMEMS-UMinho), Campus de Azurém, University of Minho, 4800-058 Guimaraes, Portugal; (I.M.); (P.S.); (G.M.)
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Computational Fluid Dynamic Technique for Assessment of How Changing Character of Blood Flow and Different Value of Hct Influence Blood Hemodynamic in Dissected Aorta. Diagnostics (Basel) 2021; 11:diagnostics11101866. [PMID: 34679564 PMCID: PMC8534802 DOI: 10.3390/diagnostics11101866] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 11/17/2022] Open
Abstract
Using computer tomography angiography (CTA) and computational structural analysis, we present a non-invasive method of mass flow rate/velocity and wall stress analysis in type B aortic dissection. Three-dimensional (3D) computer models of the aorta were calculated using pre-operative (baseline) and post-operative CT data from 12 male patients (aged from 51 to 64 years) who were treated for acute type B dissection. A computational fluid dynamics (CFD) technique was used to quantify the displacement forces acting on the aortic wall in the areas of endografts placement. The mass flow rate and wall stress were measured and quantified using the CFD technique. The CFD model indicated the places with a lower value of blood velocity and shear rate, which corelated with higher blood viscosity and a probability of thrombus appearance. Moreover, with the increase in Hct, blood viscosity also increased, while the intensity of blood flow provoked changing viscosity values in these areas. Furthermore, the velocity gradient near the tear surface caused high wall WSS; this could lead to a decreased resistance in the aorta’s wall with further implications to a patient.
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Carvalho V, Rodrigues RO, Lima RA, Teixeira S. Computational Simulations in Advanced Microfluidic Devices: A Review. MICROMACHINES 2021; 12:mi12101149. [PMID: 34683199 PMCID: PMC8539624 DOI: 10.3390/mi12101149] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/14/2021] [Accepted: 09/21/2021] [Indexed: 12/11/2022]
Abstract
Numerical simulations have revolutionized research in several engineering areas by contributing to the understanding and improvement of several processes, being biomedical engineering one of them. Due to their potential, computational tools have gained visibility and have been increasingly used by several research groups as a supporting tool for the development of preclinical platforms as they allow studying, in a more detailed and faster way, phenomena that are difficult to study experimentally due to the complexity of biological processes present in these models—namely, heat transfer, shear stresses, diffusion processes, velocity fields, etc. There are several contributions already in the literature, and significant advances have been made in this field of research. This review provides the most recent progress in numerical studies on advanced microfluidic devices, such as organ-on-a-chip (OoC) devices, and how these studies can be helpful in enhancing our insight into the physical processes involved and in developing more effective OoC platforms. In general, it has been noticed that in some cases, the numerical studies performed have limitations that need to be improved, and in the majority of the studies, it is extremely difficult to replicate the data due to the lack of detail around the simulations carried out.
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Affiliation(s)
- Violeta Carvalho
- MEtRICs, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal;
- ALGORITMI, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal;
- Correspondence:
| | - Raquel O. Rodrigues
- Center for MicroElectromechanical Systems (CMEMS-UMinho), Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal;
| | - Rui A. Lima
- MEtRICs, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal;
- CEFT, R. Dr. Roberto Frias, Faculty of Engineering of the University of Porto (FEUP), 4200-465 Porto, Portugal
| | - Senhorinha Teixeira
- ALGORITMI, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal;
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Numerical Study of the Unsteady Flow in Simplified and Realistic Iliac Bifurcation Models. FLUIDS 2021. [DOI: 10.3390/fluids6080284] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cardiovascular diseases are a major cause of death and disability worldwide and they are commonly associated with the occurrence of atherosclerotic plaque deposition in the vessel walls, a process denoted as atherosclerosis. This is a chronic and progressive inflammatory disease of large-/medium-sized blood vessels that affects blood flow profiles, with the abdominal aorta and its branches being one of the locations prone to the development of this pathology, due to their curvatures and bifurcations. In this regard, the effect of flow patterns was studied and compared for both a simplified three-dimensional model of aorta bifurcation on the iliac arteries and a realistic model of iliac bifurcation, which was constructed from a computational tomography medical image. The flow patterns were analyzed in terms of velocity and wall shear stress distribution, but a special focus was given to the size and location of the recirculation zone. The simulations were performed using the Computational Fluid Dynamics software, FLUENT, taking into account the cardiac cycle profile at the infrarenal aorta. The shear stress and the velocity distribution observed for both models indicated that higher shear stress occurred along the flow divider wall (inner wall) and low shear stress occurred along the outer walls. In addition, the results demonstrated that the wall shear stress profiles were deeply affected by the transient profile of the cardiac cycle, with the deceleration phase being the most critical phase to the occurrence of backflow.
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Abstract
Atherosclerosis is one of the main causes of cardiovascular events, namely, myocardium infarction and cerebral stroke, responsible for a great number of deaths every year worldwide. This pathology is caused by the progressive accumulation of low-density lipoproteins, cholesterol, and other substances on the arterial wall, narrowing its lumen. To date, many hemodynamic studies have been conducted experimentally and/or numerically; however, this disease is not yet fully understood. For this reason, the research of this pathology is still ongoing, mainly, resorting to computational methods. These have been increasingly used in biomedical research of atherosclerosis because of their high-performance hardware and software. Taking into account the attempts that have been made in computational techniques to simulate realistic conditions of blood flow in both diseased and healthy arteries, the present review aims to give an overview of the most recent numerical studies focused on coronary arteries, by addressing the blood viscosity models, and applied physiological flow conditions. In general, regardless of the boundary conditions, numerical studies have been contributed to a better understanding of the development of this disease, its diagnosis, and its treatment.
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Carvalho V, Maia I, Souza A, Ribeiro J, Costa P, Puga H, Teixeira S, Lima RA. In vitro
Biomodels in Stenotic Arteries to Perform Blood Analogues Flow Visualizations and Measurements: A Review. Open Biomed Eng J 2020. [DOI: 10.2174/1874120702014010087] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cardiovascular diseases are one of the leading causes of death globally and the most common pathological process is atherosclerosis. Over the years, these cardiovascular complications have been extensively studied by applying in vivo, in vitro and numerical methods (in silico). In vivo studies represent more accurately the physiological conditions and provide the most realistic data. Nevertheless, these approaches are expensive, and it is complex to control several physiological variables. Hence, the continuous effort to find reliable alternative methods has been growing. In the last decades, numerical simulations have been widely used to assess the blood flow behavior in stenotic arteries and, consequently, providing insights into the cardiovascular disease condition, its progression and therapeutic optimization. However, it is necessary to ensure its accuracy and reliability by comparing the numerical simulations with clinical and experimental data. For this reason, with the progress of the in vitro flow measurement techniques and rapid prototyping, experimental investigation of hemodynamics has gained widespread attention. The present work reviews state-of-the-art in vitro macro-scale arterial stenotic biomodels for flow measurements, summarizing the different fabrication methods, blood analogues and highlighting advantages and limitations of the most used techniques.
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Tajeddini F, Nikmaneshi MR, Firoozabadi B, Pakravan HA, Ahmadi Tafti SH, Afshin H. High precision invasive FFR, low-cost invasive iFR, or non-invasive CFR?: optimum assessment of coronary artery stenosis based on the patient-specific computational models. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3382. [PMID: 32621661 DOI: 10.1002/cnm.3382] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 05/15/2020] [Accepted: 06/28/2020] [Indexed: 06/11/2023]
Abstract
The objective of this paper is to apply computational fluid dynamic (CFD) as a complementary tool for clinical tests to not only predict the present and future status of left coronary artery stenosis but also to evaluate some clinical hypotheses. In order to assess the present status of the coronary artery stenosis severity, and thereby selecting the most appropriate type of treatment for each patient, fractional flow reserve (FFR), instantaneous wave free-ratio (iFR), and coronary flow reserve (CFR) are calculated. To examine FFR, iFR, and CFR results, the effect of geometric features of stenoses, including diameter reduction (%), lesion length (LL), and minimum lumen diameter (MLD), is studied on them. It is observed that FFR is a more conservative index than iFR and CFR to assess the severity of coronary stenosis. In addition, it is seen that FFR, iFR, and CFR decrease by increasing LL and decreasing MLD. Therefore, the morphological indices, LL/MLD and LL/MLD̂4, with the calculated conservative cut-off values equal to 5.5 and 3.6, are considered. Next, some controversial clinical hypotheses about the assessment of the severity of coronary stenosis are evaluated numerically. These include the examination of FFR, iFR, and CFR accuracies, investigating the effect of coronary hyperemia on iFR, as well as the reliability of the hybrid iFR-FFR decision-making strategy. The presented numerical model can also be used as a predictive tool to identify the atherosuseptible sites of arteries by calculating the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT).
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Affiliation(s)
- Farshad Tajeddini
- Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Mohammad Reza Nikmaneshi
- Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
- Department of Radiation Oncology, Harvard Medical School, Boston, Massachusetts, USA
| | - Bahar Firoozabadi
- Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | | | | | - Hossein Afshin
- Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
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15
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Freidoonimehr N, Arjomandi M, Sedaghatizadeh N, Chin R, Zander A. Transitional turbulent flow in a stenosed coronary artery with a physiological pulsatile flow. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3347. [PMID: 32362019 DOI: 10.1002/cnm.3347] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
The turbulence in the blood flow, caused by plaque deposition on the arterial wall, increases by the combined effect of the complex plaque geometries and the pulsatile blood flow. The correlation between the plaque geometry, the pulsatile inlet flow and the induced turbulence in a constricted artery is investigated in this study. Pressure drop, flow velocity and wall shear stress are determined for stenosed coronary artery models with three different degrees of asymmetric stenosis and for different heart working conditions. A Computational Fluid Dynamics model, validated against experimental data published in the literature, was developed to simulate the blood pulsatile flow inside a stenosed coronary artery model. The transitional flow behaviour was quantified by investigation of the changes in the turbulence kinetic energy. It was shown that the separation starts from the side of the asymmetric stenosis and spreads to its opposite side further downstream. The results suggest that there is a high risk of the formation of a secondary stenosis at a downstream distance equal to 10 times of the artery diameter at the side and bottom regions of the first stenosis due to the existence of the recirculation zones and low shear stresses. Finally, a stenosed patient-specific coronary artery model was employed to illustrate the applicability of the obtained results for real geometry models. The results of this study provide a good prediction of pressure drop and blood flow rate, which can be applied in the investigation of the heart muscle workout and the required heart power.
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Affiliation(s)
- Navid Freidoonimehr
- School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Maziar Arjomandi
- School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Nima Sedaghatizadeh
- School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Rey Chin
- School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Anthony Zander
- School of Mechanical Engineering, University of Adelaide, Adelaide, South Australia, Australia
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16
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3D Printed Biomodels for Flow Visualization in Stenotic Vessels: An Experimental and Numerical Study. MICROMACHINES 2020; 11:mi11060549. [PMID: 32485816 PMCID: PMC7344925 DOI: 10.3390/mi11060549] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/17/2020] [Accepted: 05/25/2020] [Indexed: 12/13/2022]
Abstract
Atherosclerosis is one of the most serious and common forms of cardiovascular disease and a major cause of death and disability worldwide. It is a multifactorial and complex disease that promoted several hemodynamic studies. Although in vivo studies more accurately represent the physiological conditions, in vitro experiments more reliably control several physiological variables and most adequately validate numerical flow studies. Here, a hemodynamic study in idealized stenotic and healthy coronary arteries is presented by applying both numerical and in vitro approaches through computational fluid dynamics simulations and a high-speed video microscopy technique, respectively. By means of stereolithography 3D printing technology, biomodels with three different resolutions were used to perform experimental flow studies. The results showed that the biomodel printed with a resolution of 50 μm was able to most accurately visualize flow due to its lowest roughness values (Ra = 1.8 μm). The flow experimental results showed a qualitatively good agreement with the blood flow numerical data, providing a clear observation of recirculation regions when the diameter reduction reached 60%.
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17
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Arzani A. Coronary artery plaque growth: A two-way coupled shear stress-driven model. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2020; 36:e3293. [PMID: 31820589 DOI: 10.1002/cnm.3293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/30/2019] [Accepted: 11/24/2019] [Indexed: 06/10/2023]
Abstract
Atherosclerosis in coronary arteries can lead to plaque growth, stenosis formation, and blockage of the blood flow supplying the heart tissue. Several studies have shown that hemodynamics play an important role in the growth of coronary artery plaques. Specifically, low wall shear stress (WSS) appears to be the leading hemodynamic parameter promoting atherosclerotic plaque growth, which in turn influences the blood flow and WSS distribution. Therefore, a two-way coupled interaction exists between WSS and atherosclerosis growth. In this work, a computational framework was developed to study the coupling between WSS and plaque growth in coronary arteries. Computational fluid dynamics (CFD) was used to quantify WSS distribution. Surface mesh nodes were moved in the inward normal direction according to a growth model based on WSS. After each growth stage, the geometry was updated and the CFD simulation repeated to find updated WSS values for the next growth stage. One hundred twenty growth stages were simulated in an idealized tube and an image-based left anterior descending artery. An automated framework was developed using open-source software to couple CFD simulations with growth. Changes in plaque morphology and hemodynamic patterns during different growth stages are presented. The results show larger plaque growth towards the downstream segment of the plaque, agreeing with the reported clinical observations. The developed framework could be used to establish hemodynamic-driven growth models and study the interaction between these processes.
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Affiliation(s)
- Amirhossein Arzani
- Department of Mechanical Engineering, Northern Arizona University, Flagstaff, Arizona
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