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Battistella A, Linger M, Nguyen AT, Madukwe D, Roy-Chaudhury P, Tan W. Rebuilding vascular access: from the viewpoint of mechanics and materials. Front Bioeng Biotechnol 2024; 12:1448186. [PMID: 39295847 PMCID: PMC11409097 DOI: 10.3389/fbioe.2024.1448186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Accepted: 08/22/2024] [Indexed: 09/21/2024] Open
Abstract
This review presents a comprehensive analysis of vascular access in hemodialysis, focusing on the current modalities, their associated challenges, and recent technological advancements. It closely examines the status of three primary types of vascular access: arteriovenous fistulas, arteriovenous grafts, and central venous catheters. The review delves into the complications and pathologies associated with these access types, emphasizing the mechanobiology-related pathogenesis of arteriovenous access. Furthermore, it explores recent clinical trials, biomaterials, and device innovations, highlighting novel pharmaceutical approaches, advanced materials, device designs, and cutting-edge technologies aimed at enhancing the efficacy, safety, and longevity of vascular access in hemodialysis. This synthesis of current knowledge and emerging trends underscores the dynamic evolution of vascular access strategies and their critical role in improving patient care in hemodialysis.
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Affiliation(s)
- Aurora Battistella
- Paul M. Rady Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, United States
| | - Morgan Linger
- Paul M. Rady Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, United States
- Department of Biomedical Engineering, University of Colorado at Boulder, Boulder, CO, United States
| | - Anh Thy Nguyen
- Paul M. Rady Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, United States
| | - David Madukwe
- Paul M. Rady Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, United States
| | - Prabir Roy-Chaudhury
- Department of Medicine, University of North Carolina Kidney Center, Chapel Hill, NC, United States
- WG (Bill) Hefner VA Medical Center, Salisbury, NC, United States
| | - Wei Tan
- Paul M. Rady Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, United States
- Department of Biomedical Engineering, University of Colorado at Boulder, Boulder, CO, United States
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Donghua G, Zhen L, Xiaohe W, Guocun H, Lei S. Application of modified no-touch technique in rabbit arteriovenous fistula model and its effect on venous neointimal hyperplasia. J Vasc Access 2024:11297298241256172. [PMID: 38836593 DOI: 10.1177/11297298241256172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024] Open
Abstract
BACKGROUND To investigate the technical advantages of a modified no-touch technique (MNTT) in constructing arteriovenous fistulas (AVF) compared to the conventional technique (CT) and assess its potential to reduce neointimal hyperplasia in the outflow vein. METHODS Forty-seven New Zealand rabbits were randomly divided into three groups: control, CT, and MNTT. Rabbits in control group were observed using ultrasound and then euthanized to obtain external jugular vein (EJV) for Hematoxylin-eosin (H-E). We established common carotid artery (CCA)-EJV AVF using MNTT in the MNTT group and the CT in the CT group. AVF patency and complications were compared between the CT and MNTT groups. Rabbits with patent AVF in both groups were observed using ultrasound 2 weeks after surgery to evaluate changes in the vessel diameter and blood flow spectrum of the AVFs. H-E staining measured the intima thickness of EJV adjacent to the anastomosis and histologic characteristics of the AVF at 2 and 4 weeks after surgery. RESULTS Five rabbits died after surgery with common symptoms of sneezing, coughing, runny nose, anorexia, and diarrhea; two in the MNTT group and three in the CT group. There were significant differences in the diameter (p = 0.010) and peak systolic velocities (PSV) (p = 0.001) of EJV between the CT and MNTT groups 2 weeks after surgery. Spiral laminar flow (SLF) was observed in CCA and EJV adjacent to anastomosis in the MNTT group. Additionally, histological observations showed less venous neointimal hyperplasia in the MNTT group than in the CT group 4 weeks after surgery. CONCLUSION The rabbit model of CCA-EJV AVF established using MNTT demonstrated fewer complications, larger vein diameters, and reduced venous neointimal hyperplasia, indicating that this maybe an ideal animal model to further investigate the application of MNTT in AVF surgery.
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Affiliation(s)
- Gu Donghua
- Department of Pathology, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, China
| | - Liu Zhen
- Department of Nephrology, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, China
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Wang Xiaohe
- Department of Nephrology, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, China
| | - Hou Guocun
- Department of Nephrology, Suzhou Hospital, Affiliated Hospital of Medical School, Nanjing University, Suzhou, China
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Shen Lei
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, China
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Ng O, Thomas S, Gunasekera S, Varcoe R, Barber T. Identifying problematic arteriovenous fistula with CFD-derived resistance: An exploratory study. J Biomech 2024; 171:112203. [PMID: 38908106 DOI: 10.1016/j.jbiomech.2024.112203] [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: 08/06/2023] [Revised: 05/23/2024] [Accepted: 06/19/2024] [Indexed: 06/24/2024]
Abstract
Arteriovenous fistula (AVF) is the optimal form of vascular access for most haemodialysis dependant patients; however, it is prone to the formation of stenoses that compromise utility and longevity. Whilst there are many factors influencing the development of these stenoses, pathological flow-related phenomena may also incite the formation of intimal hyperplasia, and hence a stenosis. Repeated CFD-derived resistance was calculated for six patient who had a radiocephalic AVF, treated with an interwoven nitinol stent around the juxta-anastomotic region to address access dysfunction. A three-dimensional freehand ultrasound system was used to obtain patient-specific flow profiles and geometries, before performing CFD simulations to replicate the flow phenomena in the AVF, which enabled the calculation of CFD-derived resistance. We presented six patient cases who were examined before and after treatment and our results showed a 77% decrease in resistance, recorded after a surgical intervention to address access dysfunction. Problematic AVFs were found to have high resistance, particularly in the venous segment. AVFs with no reported clinical problems, and clinical patency, had low resistance in the venous segment. There did not appear to be any relationship with clinical problems/patency and resistance values in the arterial segment. Identifying changes in resistance along the circuit allowed stenoses to be identified, independent to that determined using standard sonographic criteria. Our exploratory study reveals thatCFD-derived resistance is a promising metric that allows for non-invasive identification of diseased AVFs. The pipeline analysis enabled regular surveillance of AVF to be studied to aid with surgical planning and outcome, further exhibiting its clinical utility.
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Affiliation(s)
- Olivia Ng
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney NSW 2052, Australia.
| | - Shannon Thomas
- School of Medicine, University of New South Wales, Sydney NSW 2052, Australia; Prince of Wales Hospital, Sydney NSW 2031, Australia
| | - Sanjiv Gunasekera
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney NSW 2052, Australia
| | - Ramon Varcoe
- School of Medicine, University of New South Wales, Sydney NSW 2052, Australia; Prince of Wales Hospital, Sydney NSW 2031, Australia
| | - Tracie Barber
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney NSW 2052, Australia
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Jiang Y, Huang X, Shan Y, Chen L, Huang H, Jiang L, Liang W. The difference in diameter between radial artery and cephalic vein correlates with primary patency of radio-cephalic arteriovenous fistula. J Vasc Access 2024; 25:914-921. [PMID: 36517946 DOI: 10.1177/11297298221142387] [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] [Indexed: 02/17/2024] Open
Abstract
INTRODUCTION Autogenous radio-cephalic arteriovenous fistula (RCAVF) is preferred for chronic hemodialysis access. However, RCAVF still suffers from disappointing survival due to fistula dysfunction, with intimal hyperplasia (IH) as an underlying cause of this condition. The inconsistency of radial artery diameter (DRA) and cephalic vein diameter (DCV) is one of the factors affecting the shear disturbance, which is believed to trigger the onset of IH. However, there are no reports correlating the difference in DRA and DCV with RCAVF outcomes. METHODS This was a retrospective cohort study. Consecutive patients (n = 233) with a new RCAVF created were included if they underwent duplex ultrasound examination to evaluate preoperatively the radial artery diameter (DRA) and cephalic venous diameter (DCV). We then calculated radial artery-cephalic vein diameter difference (DCV minus DRA, termed DCV-DRA hereafter) and evaluated the association of the preoperative DCV-DRA with primary patency of RCAVF at 12 months. Subgroup analysis was also performed to explore effect modification by age, gender, radial artery diameter, and cephalic vein diameter with DCV-DRA. RESULTS After adjusting for age, gender, weight, and mean arterial pressure, the preoperative DCV-DRA was associated with primary patency of RCAVF at 12 months (adjusted Odds ratio [aOR], 1.524 per 1-mm increase; 95% confidence interval [95% CI], 1.048-2.218). The primary patency of RCAVF at 12 months was achieved in 69.4%, 71.8%,and 87.3% of patients with a preoperative DCV-DRA of ⩽-0.6 mm, (-0.5)-0.5 mm, and ⩾0.6 mm, respectively. P for trend was 0.029. Patients with DCV-DRA of ⩾0.6 mm had a much higher chance of 12-month patency than patients with DCV-DRA of ⩽-0.6 mm (aOR, 3.574; 95% CI, 1.276-10.010). Age, gender, radial artery diameter, and cephalic vein diameter did not modify the association of DCV-DRA with primary patency of RCAVF at 12 months. CONCLUSIONS Preoperative DCV-DRA may be an under-recognized predictor of RCAVF patency.
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Affiliation(s)
- Ying Jiang
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
- Department of Nephrology, Huazhong University of Science and Technology, Union Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Xiaoyan Huang
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
- Clinical Research Academy, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
| | - Ying Shan
- Clinical Research Academy, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
| | - Li Chen
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
| | - Huie Huang
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
| | - Lei Jiang
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
| | - Wei Liang
- Department of Nephrology, Peking University Shenzhen Hospital, Peking University, Shenzhen, Guangdong, China
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Baltazar S, Northrup H, Chang J, Somarathna M, Isayeva Waldrop T, Lee T, Shiu YT. Effects of endothelial nitric oxide synthase on mouse arteriovenous fistula hemodynamics. Sci Rep 2023; 13:22786. [PMID: 38123618 PMCID: PMC10733286 DOI: 10.1038/s41598-023-49573-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023] Open
Abstract
Newly created arteriovenous fistulas (AVFs) often fail to mature for dialysis use due to disturbed blood flow at and near the AVF anastomosis. The disturbed flow inhibits the endothelial nitric oxide synthase (NOS3) pathway, thus decreasing the production of nitric oxide, a vasodilator. Previously, our group reported that NOS3 expression levels affect AVF lumen size in a mouse model. In this study, we performed MRI-based computational fluid dynamics simulations to investigate the hemodynamical parameters (velocity, wall shear stress (WSS), and vorticity) in a mouse AVF model at day 7 and day 21 post-AVF creation using three NOS3 strains: overexpression (OE), knockout (KO), and wild-type (WT) control. This study is the first to reveal hemodynamics over time in mouse AVFs, consider spatial heterogeneity along the vein, and reveal the effect of NOS3 on the natural history of mouse AVF hemodynamics. From day 7 to day 21, OE has smoother streamlines and had significantly lower vorticity and WSS than WT and KO, suggesting that WSS was attempting to return to pre-surgery baseline, respectively. Our results conclude that the overexpression of NOS3 leads to desired optimal hemodynamics during AVF remodeling. Future studies can investigate enhancing the NOS3 pathway to improve AVF development.
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Affiliation(s)
- Shelly Baltazar
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, 30 N Mario Capecchi Drive, 3rd Floor South, Salt Lake City, UT, 84112, USA
| | - Hannah Northrup
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, 30 N Mario Capecchi Drive, 3rd Floor South, Salt Lake City, UT, 84112, USA
| | - Joshua Chang
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, 30 N Mario Capecchi Drive, 3rd Floor South, Salt Lake City, UT, 84112, USA
| | - Maheshika Somarathna
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tatyana Isayeva Waldrop
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timmy Lee
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Veterans Affairs Medical Center, Birmingham, AL, USA
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, 30 N Mario Capecchi Drive, 3rd Floor South, Salt Lake City, UT, 84112, USA.
- Veterans Affairs Medical Center, Salt Lake City, UT, USA.
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Rangel JF, de Almeida Santos WB, de Carvalho Costa TH, de Bessa KL, Melo JDD. Pressure Analysis in Rigid and Flexible Real Arteriovenous Fistula with Thickness Variation In Vitro. J Funct Biomater 2023; 14:310. [PMID: 37367274 DOI: 10.3390/jfb14060310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/28/2022] [Accepted: 01/05/2023] [Indexed: 06/28/2023] Open
Abstract
An arteriovenous fistula (AVF) is the access most recommended by several authors. However, its manufacture and use can cause several problems in the short, medium and long term. The study of fluid dynamics related to the structure of the AVF can provide information necessary for the reduction of these problems and a better quality of life for patients. The present study analyzed pressure variation in a rigid and flexible (thickness variation) model of AVFs manufactured based on patient data. A computed tomography was performed from which the geometry of the AVF was removed. This was treated and adapted to the pulsatile flow bench. Bench tests with simulation of systolic-diastolic pulse showed higher pressure peaks in the rigid AVF followed by the flexible model with 1 mm thickness. The inflection of the pressure values of the flexible AVF in relation to the rigid one was observed, being more expressive in the flexible AVF of 1 mm. The 1 mm flexible AVF presented an average pressure close to the physiological one and a smaller pressure drop, showing that this AVF model presents the best condition among the three to serve as a basis for the development of an AVF substitute.
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Affiliation(s)
- Jonhattan Ferreira Rangel
- Materials Science and Engineering Post-Graduation, Department of Materials Science and Engineering, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, Brazil
| | - Willyam Brito de Almeida Santos
- Mechanical Post-Graduation, Department of Mechanical Engineering, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, Brazil
| | - Thércio Henrique de Carvalho Costa
- Mechanical Post-Graduation, Department of Mechanical Engineering, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, Brazil
| | - Kleiber Lima de Bessa
- Mechanical Post-Graduation, Department of Mechanical Engineering, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, Brazil
| | - José Daniel Diniz Melo
- Materials Science and Engineering Post-Graduation, Department of Materials Science and Engineering, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, Brazil
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Cunnane CV, Houston JG, Moran DT, Broderick SP, Ross RA, Walsh MT. Spiral Laminar Flow is Associated with a Reduction in Disturbed Shear in Patient-Specific Models of an Arteriovenous Fistula. Cardiovasc Eng Technol 2023; 14:152-165. [PMID: 36151366 DOI: 10.1007/s13239-022-00644-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/03/2022] [Indexed: 11/02/2022]
Abstract
PURPOSE Areas of disturbed shear that arise following arteriovenous fistula (AVF) creation are believed to contribute to the development of intimal hyperplasia (IH). The presence of helical flow can suppress areas of disturbed shear, which may protect the vasculature from IH. Therefore, the aim of this study is to determine if helical flow, specifically spiral laminar flow (SLF), is present in patient-specific AVF models and is associated with a reduction in exposure to disturbed shear. METHODS Four AVF were imaged using MRI within the first two weeks following fistula creation. Patient-specific boundary conditions were obtained using phase-contrast MRI and applied at the inlet and outlets of each model. Computational fluid dynamics was used to analyse the hemodynamics in each model and compare the helical content of the flow to the distribution of disturbed shear. RESULTS BC-1 and RC-2 are characterised by the presence of SLF, which coincides with the lowest distribution of disturbed shear. Contrastingly, SLF is absent from BC-2 and RC-1 and experience the largest amount of disturbed shear. Interestingly, BC-2 and RC-1 developed an anastomosis stenosis, while BC-1 and RC-2 remained stenosis free. CONCLUSION These findings are in agreement with previous clinical studies and further highlight the clinical potential of SLF as a prognostic marker for a healthy AVF, as its presence correlates with an overall reduction in exposure to disturbed shear and a decrease in the incidence of AVF dysfunction, albeit in a small sample size.
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Affiliation(s)
- Connor V Cunnane
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - J Graeme Houston
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Daniel T Moran
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - Stephen P Broderick
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - Rose A Ross
- NHS Tayside Vascular Department, Ninewells Hospital, Dundee, UK
| | - Michael T Walsh
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland.
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
- Health Research Institute, University of Limerick, Limerick, Ireland.
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He Y, Shiu YT, Imrey PB, Radeva MK, Beck GJ, Gassman JJ, Northrup HM, Roy-Chaudhury P, Berceli SA, Cheung AK. Association of Shear Stress with Subsequent Lumen Remodeling in Hemodialysis Arteriovenous Fistulas. Clin J Am Soc Nephrol 2023; 18:72-83. [PMID: 36446600 PMCID: PMC10101625 DOI: 10.2215/cjn.04630422] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 10/27/2022] [Accepted: 11/03/2022] [Indexed: 12/02/2022]
Abstract
BACKGROUND Blood flow-induced wall shear stress is a strong local regulator of vascular remodeling, but its effects on arteriovenous fistula (AVF) remodeling are unclear. METHODS In this prospective cohort study, we used computational fluid dynamics simulations and statistical mixed-effects modeling to investigate the associations between wall shear stress and AVF remodeling in 120 participants undergoing AVF creation surgery. Postoperative magnetic resonance imaging data at 1 day, 6 weeks, and 6 months were used to derive current wall shear stress by computational fluid dynamic simulations and to quantify subsequent changes in AVF lumen cross-sectional area at 1-mm intervals along the proximal artery and AVF vein. RESULTS Combining artery and vein data, prior mean wall shear stress was significantly associated with lumen area expansion. Mean wall shear stress at day 1 was significantly associated with change in lumen area from day 1 to week 6 (11% larger area per interquartile range [IQR] higher mean wall shear stress, 95% confidence interval [95% CI], 5% to 18%; n =101), and mean wall shear stress at 6 weeks was significantly associated with change in lumen area from 6 weeks to month 6 (14% larger area per IQR higher, 95% CI, 3% to 28%; n =52). The association of mean wall shear stress at day 1 with lumen area expansion from day 1 to week 6 differed significantly by diabetes ( P =0.009): 27% (95% CI, 17% to 37%) larger area per IQR higher mean wall shear stress without diabetes and 9% (95% CI, -1% to 19%) with diabetes. Oscillatory shear index at day 1 was significantly associated with change in lumen area from day 1 to week 6 (5% smaller area per IQR higher oscillatory shear index, 95% CI, 3% to 7%), and oscillatory shear index at 6 weeks was significantly associated with change in lumen from 6 weeks to month 6 (7% smaller area per IQR higher oscillatory shear index, 95% CI, 2% to 11%). Wall shear stress spatial gradient was not significantly associated with subsequent remodeling. In a joint model, wall shear stress and oscillatory shear index statistically significantly interacted in their associations with lumen area expansion in a complex nonlinear fashion. CONCLUSIONS Higher wall shear stress and lower oscillatory shear index were associated with greater lumen expansion after AVF creation surgery.
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Affiliation(s)
- Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Florida
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah
- Renal Section, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Peter B. Imrey
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio
- Department of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Milena K. Radeva
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio
| | - Gerald J. Beck
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio
- Department of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Jennifer J. Gassman
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio
- Department of Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Hannah M. Northrup
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah
| | - Prabir Roy-Chaudhury
- Division of Nephrology and Hypertension, University of North Carolina, Chapel Hill, North Carolina
- Department of Medicine, W.G. (Bill) Hefner Veterans Affairs Medical Center, Salisbury, North Carolina
| | - Scott A. Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Florida
- Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, Florida
| | - Alfred K. Cheung
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah
- Renal Section, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah
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9
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Pan W, Gong L, Xiao G, Zhang L, Xiao Y, Xu C. Regular Tennis Exercise May Improve the Vascular Endothelial Function in Postmenopausal Women: The Influence of Hemodynamics. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:15749. [PMID: 36497824 PMCID: PMC9741065 DOI: 10.3390/ijerph192315749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/18/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Physical inactivity plays a role in the incidence of cardiovascular disease (CVD). Although the current guidelines for physical activity, such as the prescription of exercise, seek to combat CVD, attaining the recommended targets remains challenging. Tennis exercise has been proven to have a unique advantage in reducing the mortality of CVD, but little is known about the influence of playing tennis on impaired vascular endothelial function (VEF), which initiates CVD. Thus, this study aimed to investigate whether regular tennis participation could protect the VEF better than merely meeting the physical activity recommended by the current guidelines. A cross-sectional design was performed based on a sample of 38 healthy postmenopausal women who were matched for physical activity, of which 17 subjects had long-term tennis experience and 21 age-matched subjects regularly exercised but did not play tennis. The cardiovascular function and the body composition of all subjects were measured. We used cluster analysis to assess the overall health status. The modeling results showed that the tennis players performed better in terms of VEF than the nonplayers (10.55 ± 0.58 vs. 8.69 ± 0.52, p < 0.01, R2ad = 0.367), while the wall shear stress positively correlated with VEF (r = 0.505, p < 0.05), after controlling for age and physical activity levels. Regular tennis exercise may be a protective factor for VEF, and further study should be performed to research the role of hemodynamics in tennis exercise.
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Affiliation(s)
- Weifeng Pan
- Key Laboratory of Exercise and Physical Fitness, Ministry of Education, Beijing 100084, China
- China Institute of Sport and Health Science, Beijing Sport University, Beijing 100084, China
| | - Lijing Gong
- Key Laboratory of Exercise and Physical Fitness, Ministry of Education, Beijing 100084, China
- China Institute of Sport and Health Science, Beijing Sport University, Beijing 100084, China
| | - Guoan Xiao
- Beijing No.10 Middle School, Beijing 100039, China
| | - Lantian Zhang
- Sport Science College, Beijing Sport University, Beijing 100084, China
| | - Yiran Xiao
- Sport Science College, Beijing Sport University, Beijing 100084, China
| | - Chunyan Xu
- Sport Science College, Beijing Sport University, Beijing 100084, China
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10
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Northrup H, He Y, Le H, Berceli SA, Cheung AK, Shiu YT. Differential hemodynamics between arteriovenous fistulas with or without intervention before successful use. Front Cardiovasc Med 2022; 9:1001267. [PMID: 36407418 PMCID: PMC9669082 DOI: 10.3389/fcvm.2022.1001267] [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: 07/23/2022] [Accepted: 10/17/2022] [Indexed: 08/22/2023] Open
Abstract
A significant number of arteriovenous fistulas (AVFs) fail to maturate for dialysis. Although interventions promote maturation, functional primary patency loss is higher for AVFs with interventions (assisted maturation) than AVFs without interventions (un-assisted maturation). Although blood flow-associated hemodynamics have long been proposed to affect AVF remodeling, the optimal hemodynamic parameters for un-assisted maturation are unclear. Additionally, AVF maturation progress is generally not investigated until 6 weeks after AVF creation, and the examination is focused on the AVF's venous limb. In this exploratory study, patients (n = 6) underwent magnetic resonance imaging (MRI) at 1 day, 6 weeks, and 6 months after AVF creation surgery. Before successful use for hemodialysis, three AVFs required intervention and three did not. MRI of the AVFs were used to calculate lumen cross-sectional area (CSA) and perform computational fluid dynamics (CFD) to analyze hemodynamics, including velocity, wall shear stress (WSS), and vorticity. For the venous limb, the no-intervention group and intervention group had similar pre-surgery vein diameter and 1-day post-surgery venous CSA. However, the no-intervention group had statistically larger 1-day venous velocity (0.97 ± 0.67 m/s; mean ± SD), WSS (333 ± 336 dyne/cm2) and vorticity (1709 ± 1290 1/s) than the intervention group (velocity = 0.23 ± 0.10 m/s; WSS = 49 ± 40 dyne/cm2; vorticity = 493.1 ± 227 1/s) (P < 0.05). At 6 months, the no-intervention group had statistically larger venous CSA (43.5 ± 27.4 mm2) than the intervention group (15.1 ± 6.2 mm2) (P < 0.05). Regarding the arterial limb, no-intervention AVF arteries also had statistically larger 1-day velocity (1.17 ± 1.0 m/s), WSS (340 ± 423 dyne/cm2), vorticity (1787 ± 1694 1/s), and 6-month CSA (22.6 ± 22.7 mm2) than the intervention group (velocity = 0.64 ± 0.36 m/s; WSS = 104 ± 116 dyne/cm2, P < 0.05; vorticity = 867 ± 4551/s; CSA = 10.7 ± 6.0 mm2, P < 0.05). Larger venous velocity, WSS, and vorticity immediately after AVF creation surgery may be important for later lumen enlargement and AVF maturation, with the potential to be used as a tool to help diagnose poor AVF maturation earlier. However, future studies using a larger cohort are needed to validate this finding and determine cut off values, if any.
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Affiliation(s)
- Hannah Northrup
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
| | - Ha Le
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Scott A. Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
- Malcolm Randall Veterans Affairs Medical Center, Gainesville, FL, United States
| | - Alfred K. Cheung
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
- Veterans Affairs Medical Center, Salt Lake City, UT, United States
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
- Veterans Affairs Medical Center, Salt Lake City, UT, United States
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11
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A realistic arteriovenous dialysis graft model for hemodynamic simulations. PLoS One 2022; 17:e0269825. [PMID: 35862379 PMCID: PMC9302782 DOI: 10.1371/journal.pone.0269825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 05/30/2022] [Indexed: 11/19/2022] Open
Abstract
Objective The hemodynamic benefit of novel arteriovenous graft (AVG) designs is typically assessed using computational models that assume highly idealized graft configurations and/or simplified boundary conditions representing the peripheral vasculature. The objective of this study is to evaluate whether idealized AVG models are suitable for hemodynamic evaluation of new graft designs, or whether more realistic models are required. Methods An idealized and a realistic, clinical imaging based, parametrized AVG geometry were created. Furthermore, two physiological boundary condition models were developed to represent the peripheral vasculature. We assessed how graft geometry (idealized or realistic) and applied boundary condition models of the peripheral vasculature (physiological or distal zero-flow) impacted hemodynamic metrics related to AVG dysfunction. Results Anastomotic regions exposed to high WSS (>7, ≤40 Pa), very high WSS (>40 Pa) and highly oscillatory WSS were larger in the simulations using the realistic AVG geometry. The magnitude of velocity perturbations in the venous segment was up to 1.7 times larger in the realistic AVG geometry compared to the idealized one. When applying a (non-physiological zero-flow) boundary condition that neglected blood flow to and from the peripheral vasculature, we observed large regions exposed to highly oscillatory WSS. These regions could not be observed when using either of the newly developed distal boundary condition models. Conclusion Hemodynamic metrics related to AVG dysfunction are highly dependent on the geometry and the distal boundary condition model used. Consequently, the hemodynamic benefit of a novel graft design can be misrepresented when using idealized AVG modelling setups.
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12
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Hou Q, Tao K, Du T, Wei H, Zhang H, Chen S, Pan Y, Qiao A. A computational analysis of potential aortic dilation induced by the hemodynamic effects of bicuspid aortic valve phenotypes. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 220:106811. [PMID: 35447428 DOI: 10.1016/j.cmpb.2022.106811] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 03/01/2022] [Accepted: 04/10/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND AND OBJECTIVES The bicuspid aortic valve (BAV) is a major risk factor for the progression of aortic dilation (AD) because of the induced abnormal blood flow environment in aorta. The differences in the development of AD induced by BAV phenotypes remains unclear. Therefore, the objective of this study was to assess the potential locations of AD induced by different phenotypes of BAV. The different effects of opening orifice area and leaflet orientation on ascending aortic hemodynamics in Type-1 BAV was investigated by means of numerical simulation. METHODS Finite element dynamic analysis was performed on tricuspid aortic valve (TAV) and BAV models to simulate the motion of the leaflets and obtain the geometrical characteristics of AV at peak systole as a reference, which were used for aortic models. Then, four sets of aortic fluid models were designed according to the leaflet fusion types [TAV; BAV (left-right-coronary cusp fusion, LR; right-non-coronary cusp fusion, RN; left-non-coronary cusp fusion, LN)], and the computational fluid dynamics method was applied to compare the hemodynamic differences within the aorta at peak systole. RESULTS The maximum opening area of BAV was significantly reduced, resulting in alterations in aortic hemodynamics compared with TAV. The velocity streamlines were essentially parallel to the aortic wall in TAV. The average pressure and wall shear stress in aorta tend to be stable. In contrary, the eccentricity of BAV orifice jet resulted in high-velocity flow directed toward the ascending aorta (AA) wall and aortic arch for LR and LN; RN features an asymmetrical velocity distribution toward the outer bend of the middle AA, and eccentric flow tends to impact the distal AA. As the flow angle is associated with distinct flow impingement locations, different degrees of WSS and pressure concentration occur along the aortic wall from the AA to the aortic arch in three BAV types. CONCLUSIONS The BAV morphotype affects the aortic hemodynamics, and the abnormal blood flow associated with BAV may play a role in AD. The different BAV phenotypes determine the direction of blood flow jet and change the expression of dilation. LR is likely to cause dilation of the tubular AA; RN results in dilation of the middle AA to proximal aortic arch; and LN causes an increased incidence of the tubular AA and the proximal aortic arch.
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Affiliation(s)
- Qianwen Hou
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Keyi Tao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Tianming Du
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
| | - Hongge Wei
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Honghui Zhang
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Shiliang Chen
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Youlian Pan
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China
| | - Aike Qiao
- Faculty of Environment and Life, Beijing University of Technology, Beijing, China; Intelligent Physiological Measurement and Clinical Translation, Beijing International Base for Scientific and Technological Cooperation, Beijing, China.
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Northrup H, Somarathna M, Corless S, Falzon I, Totenhagen J, Lee T, Shiu YT. Analysis of Geometric and Hemodynamic Profiles in Rat Arteriovenous Fistula Following PDE5A Inhibition. Front Bioeng Biotechnol 2021; 9:779043. [PMID: 34926425 PMCID: PMC8675087 DOI: 10.3389/fbioe.2021.779043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/09/2021] [Indexed: 11/13/2022] Open
Abstract
Arteriovenous fistula (AVF) is essential for chronic kidney disease (CKD) patients on hemodialysis, but treatment for AVF maturation failure remains an unmet clinical need. Successful AVF remodeling occurs through sufficient lumen expansion to increase AVF blood flow and lumen area. Aberrant blood flow is thought to impair AVF remodeling, but previous literature has largely focused on hemodynamics averaged over the entire AVF or at a single location. We hypothesized that hemodynamics is heterogeneous, and thus any treatment's effect size is heterogeneous in the AVF. To test our hypothesis, we used the PDE5A inhibitor sildenafil to treat AVFs in a rat model and performed magnetic resonance imaging (MRI) based computational fluid dynamics (CFD) to generate a detailed spatial profile of hemodynamics in AVFs. 90 mg/kg of sildenafil was administered to rats in their drinking water for 14 days. On day 14 femoral AVFs were created in rats and sildenafil treatment continued for another 21 days. 21 days post-AVF creation, rats underwent non-contrast MRI for CFD and geometrical analysis. Lumen cross-sectional area (CSA) and flow rate were used to quantify AVF remodeling. Parameters used to describe aberrant blood flow include velocity magnitude, wall shear stress (WSS), oscillatory shear index (OSI), and vorticity. Geometrical parameters include arterial-venous (A-V) distance, anastomosis angle, tortuosity, and nonplanarity angle magnitude. When averaged across the entire AVF, sildenafil treated rats had significantly higher CSA, flow rate, velocity, WSS, OSI, and vorticity than control rats. To analyze heterogeneity, the vein was separated into zones: 0-5, 5-10, 10-15, and 15-20 mm from the anastomosis. In both groups: 1) CSA increased from the 0-5 to 15-20 zone; 2) velocity, WSS, and vorticity were highest in the 0-5 zone and dropped significantly thereafter; and 3) OSI increased at the 5-10 zone and then decreased gradually. Thus, the effect size of sildenafil on AVF remodeling and the relationship between hemodynamics and AVF remodeling depend on location. There was no significant difference between control and sildenafil groups for the other geometric parameters. Rats tolerated sildenafil treatment well, and our results suggest that sildenafil may be a safe and effective therapy for AVF maturation.
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Affiliation(s)
- Hannah Northrup
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Division of Nephrology and Hypertension, University of Utah Department of Internal Medicine, Salt Lake City, UT, United States
| | - Maheshika Somarathna
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Savanna Corless
- Division of Nephrology and Hypertension, University of Utah Department of Internal Medicine, Salt Lake City, UT, United States
| | - Isabelle Falzon
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Division of Nephrology and Hypertension, University of Utah Department of Internal Medicine, Salt Lake City, UT, United States
| | - John Totenhagen
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Timmy Lee
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Veterans Affairs Medical Center, Birmingham, AL, United States
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, University of Utah Department of Internal Medicine, Salt Lake City, UT, United States
- Veterans Affairs Medical Center, Salt Lake City, UT, United States
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Kingsmore D, Jackson A, Stevenson K. A critical review of surgical strategies to minimise venous stenosis in arteriovenous grafts. J Vasc Access 2021; 24:11297298211060944. [PMID: 34847754 DOI: 10.1177/11297298211060944] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
It is inevitable that complications arising from surgical procedures are ascribed to surgical technique, and this applies to venous stenosis (VS) in arteriovenous grafts. However, despite a wide range of cellular studies, computer modelling, observational series and clinical trials, there remains uncertainty on whether surgical technique contributes to VS. This article reviews evidence from basic science, fluid dynamics and clinical data to try and rationalise the main surgical options to modify the occurrence of venous stenosis. There is sufficient data from diverse sources to make recommendations on clinical practice (size of target vein, shape of anastomosis, angle of approach, distance from venous needling, trauma to the target vein) whilst at the same time this emphasises the need to carefully report the practical aspects of surgical technique in future clinical trials.
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Affiliation(s)
- David Kingsmore
- Department of Vascular Surgery, Queen Elizabeth University Hospital Trust, Glasgow, UK
- Department of Renal Transplantation, Queen Elizabeth University Hospital Trust, Glasgow, UK
| | - Andrew Jackson
- Department of Renal Transplantation, Queen Elizabeth University Hospital Trust, Glasgow, UK
| | - Karen Stevenson
- Department of Renal Transplantation, Queen Elizabeth University Hospital Trust, Glasgow, UK
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15
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Ventre J, Abou Taam S, Fullana JM, Lagrée PY. Distribution of Flow in an Arteriovenous Fistula Using Reduced-Order Models. J Biomech Eng 2021; 143:101010. [PMID: 34041533 DOI: 10.1115/1.4051282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Indexed: 11/08/2022]
Abstract
The creation of a communication between an artery and a vein (arteriovenous fistula or AVF), to speed up the blood purification during hemodialysis of patients with renal insufficiency, induces significant rheological and mechanical modifications of the vascular network. In this study, we investigated the impact of the creation of an AVF with a zero-dimensional network model of the vascular system of an upper limb and a one-dimensional model around the anastomosis. We compared the simulated distribution of flow rate in this vascular system with Doppler ultrasound measurements. We studied three configurations: before the creation of the AVF, after the creation of the AVF, and after a focal reduction due to a hyper flow rate. The zero-dimensional model predicted the bounds of the diameter of the superficial vein that respects the flow constraints, assuming a high capillary resistance. We indeed highlighted the importance of knowing the capillary resistance as it is a decisive parameter in the models. We also found that the model reproduced the Doppler measurements of flow rate in every configuration and predicted the distribution of flow in cases where the Doppler was not available. The one-dimensional model allowed studying the impact of a venous constriction on the flow distribution, and the capillary resistance was still a crucial parameter.
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Affiliation(s)
- Jeanne Ventre
- Department of Mechanical Engineering, Institut Jean Le Rond d'Alembert, UMR 7190, Sorbonne Université, CNRS, Paris 75005, France
| | - Salam Abou Taam
- Department of Thoracic and Vascular Surgery, Hopital Privé Claude Galien, Quincy-sous-Sénart 91480, France
| | - José Maria Fullana
- Department of Mechanical Engineering, Institut Jean Le Rond d'Alembert, UMR 7190, Sorbonne Université, CNRS, Paris 75005, France
| | - Pierre-Yves Lagrée
- Department of Mechanical Engineering, Institut Jean Le Rond d'Alembert, UMR 7190, Sorbonne Université, CNRS, Paris 75005, France
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16
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Chen L, Zhang W, Tan J, Hu M, Shi W, Zhang M, Wang Y, Yu B, Chen J. Morphological Lesion Types Are Associated with Primary and Secondary Patency Rates after High-Pressure Balloon Angioplasty for Dysfunctional Arteriovenous Fistulas. Blood Purif 2021; 51:425-434. [PMID: 34320498 DOI: 10.1159/000516883] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 04/07/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Neointimal hyperplasia (NIH) is believed to be the main reason for arteriovenous fistula (AVF) dysfunction, but other mechanisms are also recognized to be involved in the pathophysiological process. This study investigated whether different morphological types of AVF lesions are associated with the patency rate after percutaneous transluminal angioplasty (PTA). METHODS This retrospective study included 120 patients who underwent PTA for autogenous AVF dysfunction. All the cases were evaluated under Doppler ultrasound (DU) before intervention and divided into 3 types: Type I (NIH type), Type II (non-NIH type), and Type III (mixed type). Prognostic and clinical data were analyzed by Kaplan-Meier analysis and the Cox proportional hazards model. RESULTS There was no statistical difference in baseline variables among groups, except for lumen diameter. The primary patency rates in Type I, Type II, and Type III groups were 78.4, 93.2, and 83.2% at 6 months and 59.5, 84.7, and 75.5% at 1 year, respectively. The secondary patency rates in Type I, Type II, and Type III groups were 94.4, 97.1, and 100% at 6 months and 90.5, 97.1, and 94.7% at 1 year, respectively. The Kaplan-Meier curve showed that the primary and secondary patency rates of Type I group were lower than those of Type II group. Multivariable Cox regression analysis demonstrated that postoperative primary patency was correlated with end-to-end anastomosis (hazard ratio [HR] = 2.997, p = 0.008, 95% confidence interval [CI]: 1.328-6.764) and Type I lesion (HR = 5.395, p = 0.004, 95% CI: 1.730-16.824). CONCLUSIONS NIH-dominant lesions of AVF evaluated by DU preoperatively were a risk factor for poor primary and secondary patency rate after PTA in hemodialysis patients.
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Affiliation(s)
- Li Chen
- Department of Ultrasound, Huashan Hospital, Fudan University, Shanghai, China
| | - Weichen Zhang
- Department of Nephrology, Huashan Hospital, Fudan University, Shanghai, China,
| | - Jinyun Tan
- Department of Vascular Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Min Hu
- Department of Vascular Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Weihao Shi
- Department of Vascular Surgery, Pudong Hospital, Fudan University, Shanghai, China
| | - Minmin Zhang
- Department of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
| | - Yong Wang
- Department of Ultrasound, Huashan Hospital, Fudan University, Shanghai, China
| | - Bo Yu
- Department of Vascular Surgery, Huashan Hospital, Fudan University, Shanghai, China.,Department of Vascular Surgery, Pudong Hospital, Fudan University, Shanghai, China
| | - Jing Chen
- Department of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
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17
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Boire TC, Himmel LE, Yu F, Guth CM, Dollinger BR, Werfel TA, Balikov DA, Duvall CL. Effect of pore size and spacing on neovascularization of a biodegradble shape memory polymer perivascular wrap. J Biomed Mater Res A 2021; 109:272-288. [PMID: 32490564 PMCID: PMC8270373 DOI: 10.1002/jbm.a.37021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/11/2020] [Accepted: 04/19/2020] [Indexed: 12/13/2022]
Abstract
Neointimal hyperplasia (NH) is a main source of failures in arteriovenous fistulas and vascular grafts. Several studies have demonstrated the promise of perivascular wraps to reduce NH via promotion of adventitial neovascularization and providing mechanical support. Limited clinical success thus far may be due to inappropriate material selection (e.g., nondegradable, too stiff) and geometric design (e.g., pore size and spacing, diameter). The influence of pore size and spacing on implant neovascularization is investigated here for a new biodegradable, thermoresponsive shape memory polymer (SMP) perivascular wrap. Following an initial pilot, 21 mice were each implanted with six scaffolds: four candidate SMP macroporous designs (a-d), a nonporous SMP control (e), and microporous GORETEX (f). Mice were sacrificed after 4 (N = 5), 14 (N = 8), and 28 (N = 8) days. There was a statistically significant increase in neovascularization score between all macroporous groups compared to nonporous SMP (p < .023) and microporous GORETEX (p < .007) controls at Day 28. Wider-spaced, smaller-sized pore designs (223 μm-spaced, 640 μm-diameter Design c) induced the most robust angiogenic response, with greater microvessel number (p < .0114) and area (p < .0055) than nonporous SMPs and GORETEX at Day 28. This design also produced significantly greater microvessel density than nonporous SMPs (p = 0.0028) and a smaller-spaced, larger-sized pore (155 μm-spaced, 1,180 μm-sized Design b) design (p = .0013). Strong neovascularization is expected to reduce NH, motivating further investigation of this SMP wrap with controlled pore spacing and size in more advanced arteriovenous models.
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Affiliation(s)
- Timothy C Boire
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Lauren E Himmel
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Fang Yu
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Christy M Guth
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bryan R Dollinger
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Thomas A Werfel
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Biomedical Engineering Program, University of Mississippi, Oxford, Mississippi, USA
| | - Daniel A Balikov
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Craig L Duvall
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
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Hosseini V, Mallone A, Nasrollahi F, Ostrovidov S, Nasiri R, Mahmoodi M, Haghniaz R, Baidya A, Salek MM, Darabi MA, Orive G, Shamloo A, Dokmeci MR, Ahadian S, Khademhosseini A. Healthy and diseased in vitro models of vascular systems. LAB ON A CHIP 2021; 21:641-659. [PMID: 33507199 DOI: 10.1039/d0lc00464b] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Irregular hemodynamics affects the progression of various vascular diseases, such atherosclerosis or aneurysms. Despite the extensive hemodynamics studies on animal models, the inter-species differences between humans and animals hamper the translation of such findings. Recent advances in vascular tissue engineering and the suitability of in vitro models for interim analysis have increased the use of in vitro human vascular tissue models. Although the effect of flow on endothelial cell (EC) pathophysiology and EC-flow interactions have been vastly studied in two-dimensional systems, they cannot be used to understand the effect of other micro- and macro-environmental parameters associated with vessel wall diseases. To generate an ideal in vitro model of the vascular system, essential criteria should be included: 1) the presence of smooth muscle cells or perivascular cells underneath an EC monolayer, 2) an elastic mechanical response of tissue to pulsatile flow pressure, 3) flow conditions that accurately mimic the hemodynamics of diseases, and 4) geometrical features required for pathophysiological flow. In this paper, we review currently available in vitro models that include flow dynamics and discuss studies that have tried to address the criteria mentioned above. Finally, we critically review in vitro fluidic models of atherosclerosis, aneurysm, and thrombosis.
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Affiliation(s)
- Vahid Hosseini
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Anna Mallone
- Institute of Regenerative Medicine, University of Zurich, Zurich CH-8952, Switzerland
| | - Fatemeh Nasrollahi
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Serge Ostrovidov
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and Department of Radiological Sciences, University of California-Los Angeles, CA 90095, USA
| | - Rohollah Nasiri
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Department of Mechanical Engineering, Sharif University of Technology, Tehran 1136511155, Iran
| | - Mahboobeh Mahmoodi
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Department of Biomedical Engineering, Yazd Branch, Islamic Azad University, Yazd 8915813135, Iran
| | - Reihaneh Haghniaz
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Avijit Baidya
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA
| | - M Mehdi Salek
- School of Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Mohammad Ali Darabi
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Gorka Orive
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country UPV/EHU, Paseo de la Universidad 7, Vitoria-Gasteiz 01006, Spain and Biomedical Research Networking Centre in Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz 01007, Spain
| | - Amir Shamloo
- Department of Mechanical Engineering, Sharif University of Technology, Tehran 1136511155, Iran
| | - Mehmet R Dokmeci
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Samad Ahadian
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
| | - Ali Khademhosseini
- Center for Minimally Invasive Therapeutics (C-MIT), University of California-Los Angeles, CA 90095, USA and California NanoSystems Institute and Department of Bioengineering, University of California-Los Angeles, CA 90095, USA and Terasaki Institute for Biomedical Innovation, Los Angeles, CA 90024, USA.
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Wu Y, Wang F, Wang T, Zheng Y, You L, Xue J. Association of Retinol-Binding Protein 4 with Arteriovenous Fistula Dysfunction in Hemodialysis Patients. Blood Purif 2021; 50:906-913. [PMID: 33556944 DOI: 10.1159/000513418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/27/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Arteriovenous fistula (AVF) is the most common vascular access for patients undergoing hemodialysis (HD). Neointimal hyperplasia (NIH) might be a potential mechanism of AVF dysfunction. Retinol-binding protein 4 (RBP4) may play an important role in the pathogenesis of NIH. The aim of this study was to investigate whether AVF dysfunction is associated with serum concentrations of RBP4 in HD subjects. METHODS A cohort of 65 Chinese patients undergoing maintenance HD was recruited between November 2017 and June 2019. The serum concentrations of RBP4 of each patient were measured with the ELISA method. Multivariate logistic regression was used to analyze data on demographics, biochemical parameters, and serum RBP4 level to predict AVF dysfunction events. The cutoff for serum RBP4 level was derived from the highest score obtained on the Youden index. Survival data were analyzed with the Cox proportional hazards regression analysis and Kaplan-Meier method. RESULTS Higher serum RBP4 level was observed in patients with AVF dysfunction compared to those without AVF dysfunction events (174.3 vs. 168.4 mg/L, p = 0.001). The prevalence of AVF dysfunction events was greatly higher among the high RBP4 group (37.5 vs. 4.88%, p = 0.001). In univariate analysis, serum RBP4 level was statistically significantly associated with the risk of AVF dysfunction (OR = 1.015, 95% CI 1.002-1.030, p = 0.030). In multivariate analysis, each 1.0 mg/L increase in RBP4 level was associated with a 1.023-fold-increased risk of AVF dysfunction (95% CI for OR: 1.002-1.045; p = 0.032). The Kaplan-Meier survival analysis indicated that the incidence of AVF dysfunction events in the high RBP4 group was significantly higher than that in the low-RBP4 group (p = 0.0007). Multivariate Cox regressions demonstrated that RBP4 was an independent risk factor for AVF dysfunction events in HD patients (HR = 1.015, 95% CI 1.001-1.028, p = 0.033). CONCLUSIONS HD patients with higher serum RBP4 concentrations had a relevant higher incidence of arteriovenous dysfunction events. Serum RBP4 level was an independent risk factor for AVF dysfunction events in HD patients.
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Affiliation(s)
- Yuanhao Wu
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China.,Department of Nephrology, Huashan Hospital Affiliated to Fudan University, Shanghai, China
| | - Fan Wang
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China
| | - Tingting Wang
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China.,Department of Nephrology, Huashan Hospital Affiliated to Fudan University, Shanghai, China
| | - Yin Zheng
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China.,Department of Nephrology, Huashan Hospital Affiliated to Fudan University, Shanghai, China
| | - Li You
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China, .,Department of Nephrology, Huashan Hospital Affiliated to Fudan University, Shanghai, China,
| | - Jun Xue
- Department of Nephrology, North Huashan Hospital Affiliated to Fudan University, Shanghai, China.,Department of Nephrology, Huashan Hospital Affiliated to Fudan University, Shanghai, China
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20
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Sun CY, Zhou LF, Song L, Lan LJ, Han XW, Zhang GR, Mo YW, Zheng SQ, Chen YG, Fu X. How to Reduce the Risk of Arteriovenous Fistula Dysfunction by Observing Prepump Arterial Pressure during Hemodialysis: A Multicenter Retrospective Study. Blood Purif 2021; 50:800-807. [PMID: 33530090 DOI: 10.1159/000512352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 10/14/2020] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Prepump arterial (Pa) pressure indicates the ease or difficulty with which the blood pump can draw blood from the vascular access (VA) during hemodialysis. Some studies have suggested that the absolute value of the Pa pressure to the extracorporeal blood pump flow (Qb) ratio set on the machine (|Pa/Qb|) can reflect the dysfunction of VA. This study was conducted to explore the impact of arteriovenous fistula (AVF) dysfunction and to explore the clinical reference value of |Pa/Qb|. METHODS We retrospectively identified adults who underwent hemodialysis at 3 hospitals. Data were acquired from electronic health records. We evaluated the pattern of the association between |Pa/Qb| and AVF dysfunction during 1 year using a Cox proportional hazards regression model with restricted cubic splines. Then, the patients were grouped based on the results, and hazard ratios were compared for different intervals of |Pa/Qb|. RESULTS A total of 490 patients were analyzed, with an average age of 55 (44, 66) years. There were a total of 85 cases of AVF dysfunction, of which 50 cases were stenosis and 35 cases were thrombosis. There was a U-shaped association between |Pa/Qb| and the risk of AVF dysfunction (p for nonlinearity <0.001). |Pa/Qb| values <0.30 and >0.52 increased the risk of AVF dysfunction. Compared with the group with a |Pa/Qb| value between 0.30 and 0.52, the groups with |Pa/Qb| <0.30 and |Pa/Qb| >0.52 had a 4.04-fold (p = 0.002) and 3.41-fold (p < 0.001) greater risk of AVF dysfunction, respectively. CONCLUSIONS The appropriate range of |Pa/Qb| is between 0.30 and 0.52. When |Pa/Qb| is <0.30 or >0.52, the patient's AVF function or Qb setting should be reevaluated to prevent subsequent failure.
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Affiliation(s)
- Chun-Yan Sun
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.,School of Nursing, Southern Medical University, Guangzhou, China
| | - Li-Fang Zhou
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Li Song
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Li-Juan Lan
- Blood Purification Center, Shenzhen People's Hospital, Shenzhen, China
| | - Xiao-Wei Han
- Division of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Guan-Rong Zhang
- Information and Statistical Center, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Ya-Wen Mo
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Shu-Qian Zheng
- Division of Nephrology, Guangzhou Nansha Central Hospital, Guangzhou, China
| | - Ying-Gui Chen
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Xia Fu
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China, .,School of Nursing, Southern Medical University, Guangzhou, China,
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Quicken S, Delhaas T, Mees BME, Huberts W. Haemodynamic optimisation of a dialysis graft design using a global optimisation approach. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3423. [PMID: 33249781 PMCID: PMC7900962 DOI: 10.1002/cnm.3423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 10/14/2020] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
Disturbed flow and the resulting non-physiological wall shear stress (WSS) at the graft-vein anastomosis play an important role in arteriovenous graft (AVG) patency loss. Modifying graft geometry with helical features is a popular approach to minimise the occurrence of detrimental haemodynamics and to potentially increase graft longevity. Haemodynamic optimisation of AVGs typically requires many computationally expensive computational fluid dynamics (CFD) simulations to evaluate haemodynamic performance of different graft designs. In this study, we aimed to develop a haemodynamically optimised AVG by using an efficient meta-modelling approach. A training dataset containing CFD evaluations of 103 graft designs with helical features was used to develop computationally low-cost meta-models for haemodynamic metrics related to graft dysfunction. During optimisation, the meta-models replaced CFD simulations that were otherwise needed to evaluate the haemodynamic performance of possible graft designs. After optimisation, haemodynamic performance of the optimised graft design was verified using a CFD simulation. The obtained optimised graft design contained both a helical graft centreline and helical ridge. Using the optimised design, the magnitude of flow disturbances and the size of the anastomotic areas exposed to non-physiological WSS was successfully reduced compared to a regular straight graft. Our meta-modelling approach allowed to reduce the total number of CFD model evaluations required for our design optimisation by approximately a factor 2000. The applied efficient meta-modelling technique was successful in identifying an optimal, helical graft design at relatively low computational costs. Future studies should evaluate the in vivo benefits of the developed graft design.
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Affiliation(s)
- Sjeng Quicken
- Department of Biomedical EngineeringCARIM School for Cardiovascular Diseases, Maastricht UniversityMaastrichtThe Netherlands
- Eindhoven University of TechnologyDepartment of Biomedical EngineeringEindhovenNetherlands
| | - Tammo Delhaas
- Department of Biomedical EngineeringCARIM School for Cardiovascular Diseases, Maastricht UniversityMaastrichtThe Netherlands
| | - Barend M. E. Mees
- Department of Vascular SurgeryMaastricht University Medical CentreMaastrichtthe Netherlands
| | - Wouter Huberts
- Department of Biomedical EngineeringCARIM School for Cardiovascular Diseases, Maastricht UniversityMaastrichtThe Netherlands
- Eindhoven University of TechnologyDepartment of Biomedical EngineeringEindhovenNetherlands
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22
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Model Verification and Error Sensitivity of Turbulence-Related Tensor Characteristics in Pulsatile Blood Flow Simulations. FLUIDS 2020. [DOI: 10.3390/fluids6010011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Model verification, validation, and uncertainty quantification are essential procedures to estimate errors within cardiovascular flow modeling, where acceptable confidence levels are needed for clinical reliability. While more turbulent-like studies are frequently observed within the biofluid community, practical modeling guidelines are scarce. Verification procedures determine the agreement between the conceptual model and its numerical solution by comparing for example, discretization and phase-averaging-related errors of specific output parameters. This computational fluid dynamics (CFD) study presents a comprehensive and practical verification approach for pulsatile turbulent-like blood flow predictions by considering the amplitude and shape of the turbulence-related tensor field using anisotropic invariant mapping. These procedures were demonstrated by investigating the Reynolds stress tensor characteristics in a patient-specific aortic coarctation model, focusing on modeling-related errors associated with the spatiotemporal resolution and phase-averaging sampling size. Findings in this work suggest that attention should also be put on reducing phase-averaging related errors, as these could easily outweigh the errors associated with the spatiotemporal resolution when including too few cardiac cycles. Also, substantially more cycles are likely needed than typically reported for these flow regimes to sufficiently converge the phase-instant tensor characteristics. Here, higher degrees of active fluctuating directions, especially of lower amplitudes, appeared to be the most sensitive turbulence characteristics.
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23
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Characterization of anisotropic turbulence behavior in pulsatile blood flow. Biomech Model Mechanobiol 2020; 20:491-506. [PMID: 33090334 PMCID: PMC7979666 DOI: 10.1007/s10237-020-01396-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 10/07/2020] [Indexed: 11/10/2022]
Abstract
Turbulent-like hemodynamics with prominent cycle-to-cycle flow variations have received increased attention as a potential stimulus for cardiovascular diseases. These turbulent conditions are typically evaluated in a statistical sense from single scalars extracted from ensemble-averaged tensors (such as the Reynolds stress tensor), limiting the amount of information that can be used for physical interpretations and quality assessments of numerical models. In this study, barycentric anisotropy invariant mapping was used to demonstrate an efficient and comprehensive approach to characterize turbulence-related tensor fields in patient-specific cardiovascular flows, obtained from scale-resolving large eddy simulations. These techniques were also used to analyze some common modeling compromises as well as MRI turbulence measurements through an idealized constriction. The proposed method found explicit sites of elevated turbulence anisotropy, including a broad but time-varying spectrum of characteristics over the flow deceleration phase, which was different for both the steady inflow and Reynolds-averaged Navier–Stokes modeling assumptions. Qualitatively, the MRI results showed overall expected post-stenotic turbulence characteristics, however, also with apparent regions of unrealizable or conceivably physically unrealistic conditions, including the highest turbulence intensity ranges. These findings suggest that more detailed studies of MRI-measured turbulence fields are needed, which hopefully can be assisted by more comprehensive evaluation tools such as the once described herein.
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24
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He Y, Northrup H, Roy-Chaudhury P, Cheung AK, Berceli SA, Shiu YT. Analyses of hemodialysis arteriovenous fistula geometric configuration and its associations with maturation and reintervention. J Vasc Surg 2020; 73:1778-1786.e1. [PMID: 33091518 DOI: 10.1016/j.jvs.2020.09.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/22/2020] [Indexed: 02/04/2023]
Abstract
OBJECTIVE An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis; however, the rates of AVF maturation failure and reintervention remain high. We investigated the AVF geometric parameters and their associations with AVF physiologic maturation and reintervention in a prospective multicenter study. METHODS From 2011 to 2016, patients undergoing vein end-to-artery side upper extremity AVF creation surgery were recruited. Contrast-free dark blood and phase-contrast magnetic resonance imaging (MRI) scans were performed using 3.0T scanners to obtain the AVF lumen geometry and flow rates, respectively, at postoperative day 1, week 6, and month 6. The arteriovenous anastomosis angle, nonplanarity, and tortuosity of the fistula were calculated according to the lumen centerlines. AVFs were considered physiologically matured if, using the week 6 MRI data, the flow rate was ≥500 mL/min and the minimum vein lumen diameter was ≥5 mm. The associations of these geometric parameters with AVF maturation and reintervention due to perianastomotic and mid-vein stenosis within 1 year were assessed. RESULTS A total of 111 patients had a usable day 1 MRI scan, with most having upper arm AVFs (n = 73). Compared with the forearm AVFs, upper arm AVFs had greater anastomosis angles (P < .001), larger deviations from a plane (nonplanarity; P = .002), and more prominent tortuosity (P = .038) at day 1. These parameters significantly increased between day 1 and week 6 in upper arm AVFs. In contrast, significant changes in these parameters in forearm AVFs were not observed. The rate of maturation was 54% and 86% for forearm and upper arm AVFs, respectively. None of the geometric parameters at day 1 were associated with AVF maturation in either location. The rate of reintervention was 24% and 30% for forearm and upper arm AVFs, respectively, with a larger nonplanarity angle at day 1 associated with less reintervention (30° ± 15° vs 21° ± 10°; P = .034) in upper arm AVFs only. This relationship was unchanged after adjusting for age, sex, race, dialysis status, or diabetes. CONCLUSIONS In our study, upper arm fistulas had a larger anastomosis angle, were more nonplanar, and had more tortuous veins than forearm fistulas. For upper arm fistulas, a larger nonplanarity angle is associated with a lower rate of reintervention within 1 year. Once confirmed, vascular surgeons could consider increasing the nonplanarity angle by incorporating a tension-free gentle curvature in the proximal segment of the mobilized vein to reduce reinterventions when creating an upper arm fistula.
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Affiliation(s)
- Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Hannah Northrup
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah
| | - Prabir Roy-Chaudhury
- Division of Nephrology and Hypertension, University of North Carolina, Chapel Hill, NC; Department of Medicine, W. G. (Bill) Hefner Veterans Affairs Medical Center, Salisbury, NC
| | - Alfred K Cheung
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah; Renal Section, Medical Service, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Scott A Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla; Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, Fla
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, University of Utah, Salt Lake City, Utah; Renal Section, Medical Service, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah.
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25
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Colley E, Simmons A, Varcoe R, Thomas S, Barber T. Arteriovenous fistula maturation and the influence of fluid dynamics. Proc Inst Mech Eng H 2020; 234:1197-1208. [DOI: 10.1177/0954411920926077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Arteriovenous fistula creation is the preferred vascular access for haemodialysis therapy, but has a large failure rate in the maturation period. This period generally lasts 6 to 8 weeks after surgical creation, in which the vein and artery undergo extensive vascular remodelling. In this review, we outline proposed mechanisms for both arteriovenous fistula maturation and arteriovenous fistula failure. Clinical, animal and computational studies have not yet shown a definitive link between any metric and disease development, although a number of theories based on wall shear stress metrics have been suggested. Recent work allowing patient-based longitudinal studies may hold the key to understanding arteriovenous fistula maturation processes.
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Affiliation(s)
- Eamonn Colley
- School of Mechanical Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Anne Simmons
- School of Mechanical Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Ramon Varcoe
- Prince of Wales Hospital, Sydney, NSW, Australia
| | | | - Tracie Barber
- School of Mechanical Engineering, University of New South Wales, Sydney, NSW, Australia
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26
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The Hemodynamic Effect of Enhanced External Counterpulsation Treatment on Atherosclerotic Plaque in the Carotid Artery: A Framework of Patient-Specific Computational Fluid Dynamics Analysis. Cardiol Res Pract 2020; 2020:5903790. [PMID: 32411447 PMCID: PMC7210552 DOI: 10.1155/2020/5903790] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/18/2019] [Accepted: 01/21/2020] [Indexed: 01/28/2023] Open
Abstract
Long-term enhanced external counterpulsation (EECP) therapy has been recommended for antiatherogenesis in recent clinical observations and trials. However, the precise mechanism underlying the benefits has not been fully clarified. To quantify the effect of EECP intervention on arterial hemodynamic environment, a framework of numerical assessment was introduced using a parallel computing algorithm. A 3D endothelial surface of the carotid artery with mild atherosclerotic plaque was constructed from images of magnetic resonance angiography (MRA). Physiologic boundary conditions were derived from images of the ultrasound flow velocity spectrum measured at the common carotid artery and before and during EECP intervention. Hemodynamic factors relating to wall shear stress (WSS) and its spatial and temporal fluctuations were calculated and analyzed, which included AWSS, OSI, and AWSSG. Measuring and computational results showed that diastole blood pressure, perfusion, and WSS level in carotid bifurcation were significantly increased during EECP intervention. Mean AWSS level throughout the model increased by 16.9%, while OSI level did not show a significant change during EECP. We thus suggested that long-term EECP treatment might inhibit the initiation and development of atherosclerotic plaque via improving the hemodynamic environment in the carotid artery. Meanwhile, EECP performance induced a 19.6% increase in AWSSG level, and whether it would influence the endothelial functions may need a further study. Moreover, the numerical method proposed in this study was expected to be useful for the instant assessment of clinical application of EECP .
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27
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Sun CY, Mo YW, Lan LJ, Han XW, Song L, Zhang GR, Zhou LF, Zheng SQ, Chen YG, Liu SX, Liang XL, Fu X. It is time to implement prepump arterial pressure monitoring during hemodialysis: A retrospective multicenter study. J Vasc Access 2020; 21:938-944. [PMID: 32345102 DOI: 10.1177/1129729820917266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
INTRODUCTION Prepump arterial pressure (Pa) indicates the ease or difficulty with which the blood pump can draw blood from vascular access (inflow) during hemodialysis. The absolute prepump arterial pressure to blood pump speed (Qb) ratio (|Pa/Qb|) may reflect the dysfunction of other vascular accesses. There is no consensus on the impact of |Pa/Qb| on arteriovenous fistula dysfunction. This study aimed to demonstrate the impact of |Pa/Qb| on arteriovenous fistula dysfunction. METHODS In this retrospective analysis, 490 hemodialysis patients with arteriovenous fistula from three hospitals were enrolled. Data were extracted from the I-Diapro database and hospital case systems. The absolute values for |Pa/Qb| and other data collected in the first month of enrollment were used to predict arteriovenous fistula dysfunction and determine the |Pa/Qb| cutoff value. Based on this value, patients were grouped, and 1-year arteriovenous fistula function was analyzed. Patients were followed until arteriovenous fistula dysfunction, until access type replacement, or for 12 months. RESULTS The area under the receiver operating characteristic curve for fistula dysfunction over 1 year was 0.65, with an optimal |Pa/Qb| value, sensitivity, and specificity of 0.499, 60.7%, and 72.6%, respectively. |Pa/Qb| > 0.499 was associated with earlier intervention (317.37 ± 7.68 vs 345.96 ± 3.64 days), lower survival (p < 0.001), and a 3.26-fold greater risk of arteriovenous fistula dysfunction (p < 0.001) than |Pa/Qb| ⩽ 0.499. CONCLUSIONS |Pa/Qb| was an independent risk factor for arteriovenous fistula dysfunction. Nurses should emphasize |Pa/Qb| monitoring and properly set blood pump speed according to this ratio to protect arteriovenous fistula function. |Pa/Qb| > 0.499 might be a predictive measure of arteriovenous fistula dysfunction.
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Affiliation(s)
- Chun-Yan Sun
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Ya-Wen Mo
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Li-Juan Lan
- Blood Purification Center, Shenzhen People's Hospital, Shenzhen, China
| | - Xiao-Wei Han
- Division of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Li Song
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Guan-Rong Zhang
- Information and Statistical Center, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Li-Fang Zhou
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Shu-Qian Zheng
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangzhou Nansha Central Hospital, Guangzhou, China
| | - Ying-Gui Chen
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Shuang-Xin Liu
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Xin-Ling Liang
- Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Xia Fu
- School of Nursing, Southern Medical University, Guangzhou, China.,Division of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
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Carroll JE, Colley ES, Thomas SD, Varcoe RL, Simmons A, Barber TJ. Tracking geometric and hemodynamic alterations of an arteriovenous fistula through patient-specific modelling. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 186:105203. [PMID: 31765935 DOI: 10.1016/j.cmpb.2019.105203] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/10/2019] [Accepted: 11/11/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND OBJECTIVE The use of patient-specific CFD modelling for arteriovenous fistulae (AVF) has shown great clinical potential for improving surveillance, yet the use of imaging modes such as MRI and CT for the 3D geometry acquisition presents high costs and exposure risks, preventing regular use. We have developed an ultrasound based procedure to bypass these limitations. METHODS A scanning procedure and processing pipeline was developed specifically for CFD modelling of AVFs, using a freehand ultrasound setup combining B-mode scanning with 3D probe motion tracking. The scanning procedure involves sweeping along the vasculature to create a high density stack of B-mode frames containing the lumen geometry. This stack is converted into a continuous volume and transient flow waveforms are recorded at the boundaries, synchronised with ECG and automatically digitised, forming realistic boundary conditions for the CFD models. This is demonstrated on a diseased patient-specific AVF. RESULTS The three scans obtained using this procedure varied in geometry and flow behaviour, with regions of disease located in the first two scans. The outcome of the second procedure seen in the third scan indicated successful restoration with no sites of disease and higher flow. The models gave insight into the lumenal changes in diameter for both the artery and vein segments, as well as characterising hemodynamic behaviours in both the diseased and restored states. Vascular segment resistances obtained from the CFD models indicate a significant reduction once disease was removed, resulting in much higher flows enabling the patient to resume dialysis. CONCLUSION The methodology described in this study allowed for a multifaceted analysis and high level tracking in terms of both geometry and flow behaviours for a patient case, demonstrating significant clinical utility and practicality, as well as enabling further research into vascular disease progression in AVFs through longitudinal analysis.
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Affiliation(s)
- John E Carroll
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, 2052, NSW, Australia
| | - Eamonn S Colley
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, 2052, NSW, Australia
| | - Shannon D Thomas
- Prince of Wales Hospital, Sydney, 2031, NSW, Australia; School of Medicine, University of New South Wales, Sydney, 2052, NSW, Australia
| | - Ramon L Varcoe
- Prince of Wales Hospital, Sydney, 2031, NSW, Australia; School of Medicine, University of New South Wales, Sydney, 2052, NSW, Australia
| | - Anne Simmons
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, 2052, NSW, Australia
| | - Tracie J Barber
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, 2052, NSW, Australia.
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29
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Cheng Y, Qiao A, Yang Y, Fan X. Numerical Simulation of Hemodynamics in Two Models for Total Anomalous Pulmonary Venous Connection Surgery. Front Physiol 2020; 11:206. [PMID: 32210842 PMCID: PMC7076188 DOI: 10.3389/fphys.2020.00206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 02/21/2020] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE To numerically compare the prospective hemodynamic outcomes between a new window surgery and a traditional surgery in the treatment of supracardiac total anomalous pulmonary venous connection (S-TAPVC). METHODS A 3D geometry model, composed of pulmonary vein (PV) and left atrium (LA), was reconstructed based on summarized data with S-TAPVC. Two surgery models were established based on this model. One is the traditional surgery model, where an elliptical anastomosis was created by incising and stitching the LA and the common vein (CV) along the axis of the CV. The other is the new window surgery model, where the CV was incised with an H-shaped orifice, and LA was incised with a transposed H-shaped orifice, and then the orifice edges were stitched like a window. Two models with a relative cross sectional area (RCSA) of 300 mm2/m2 and 500 mm2/m2 were established, which correspond to traditional surgery and window surgery. Numerical simulation of hemodynamics was carried out. The velocity, left atrium and pulmonary vein pressure, the pressure difference of anastomosis and the energy conversion efficiency were analyzed to evaluate the prospective hemodynamic outcomes of these two operations. RESULTS Window surgery presented a lower blood flow velocity, pressure difference, and the WSS at the anastomosis, compared to traditional surgery. In terms of energy loss, the power conversion efficiency of window surgery was significantly higher than that of traditional surgery, with 66.8% and 53.5%, respectively. CONCLUSION The new window surgery demonstrates a lower pressure difference of anastomosis and higher energy conversion efficiency, which may be a better choice compared with the traditional surgery for S-TAPVC patient.
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Affiliation(s)
- Yeyang Cheng
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Aike Qiao
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Yao Yang
- Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Xiangming Fan
- Beijing Anzhen Hospital, Capital Medical University, Beijing, China
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30
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De Nisco G, Gallo D, Siciliano K, Tasso P, Lodi Rizzini M, Mazzi V, Calò K, Antonucci M, Morbiducci U. Hemodialysis arterio-venous graft design reducing the hemodynamic risk of vascular access dysfunction. J Biomech 2020; 100:109591. [PMID: 31902610 DOI: 10.1016/j.jbiomech.2019.109591] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/04/2019] [Accepted: 12/18/2019] [Indexed: 11/18/2022]
Abstract
Although arterio-venous grafts (AVGs) represent the second choice as permanent vascular access for hemodialysis, this solution is still affected by a relevant failure rate due to graft thrombosis, and development of neointimal hyperplasia (IH) at the distal vein. As a key role in these processes has been attributed to the abnormal hemodynamics establishing in the distal vein, the optimization of AVGs design aimed at minimizing flow disturbances would reduce AVG hemodynamic-related risks. In this study we used computational fluid dynamics to investigate the impact of alternative AVG designs on the reduction of IH and thrombosis risk at the distal venous anastomosis. The performance of the newly designed AVGs was compared to that of commercially available devices. In detail, a total of eight AVG models in closed-loop configuration were constructed: two models resemble the commercially available straight conventional and helical-shaped AVGs; six models are characterized by the insertion of a flow divider (FD), straight or helical shaped, differently positioned inside the graft. Unfavorable hemodynamic conditions were analyzed by assessing the exposure to disturbed shear at the distal vein. Bulk flow was investigated in terms of helical blood flow features, potential thrombosis risk, and pressure drop over the graft. Findings from this study clearly show that using a helically-shaped FD located at the venous side of the graft could induce beneficial helical flow patterns that, minimizing flow disturbances, reduce the IH-related risk of failure at the distal vein, with a clinically irrelevant increase in thrombosis risk and pressure drop over the graft.
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Affiliation(s)
- Giuseppe De Nisco
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Diego Gallo
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Katia Siciliano
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Paola Tasso
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Maurizio Lodi Rizzini
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Valentina Mazzi
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Karol Calò
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | | | - Umberto Morbiducci
- Polito(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
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31
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Quicken S, Huberts W, Tordoir J, van Loon M, Delhaas T, Mees B. Computational Modelling Based Recommendation on Optimal Dialysis Needle Positioning and Dialysis Flow in Patients With Arteriovenous Grafts. Eur J Vasc Endovasc Surg 2020; 59:288-294. [DOI: 10.1016/j.ejvs.2019.08.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/12/2019] [Accepted: 08/12/2019] [Indexed: 01/06/2023]
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32
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史 宇. Progress in the Computer Simulation Study of the Hemodynamics in Direct Aspiration Thrombectomy for the Treatment of Acute Ischemic Stroke. Biophysics (Nagoya-shi) 2020. [DOI: 10.12677/biphy.2020.84005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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33
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Cunnane CV, Cunnane EM, Moran DT, Walsh MT. The presence of helical flow can suppress areas of disturbed shear in parameterised models of an arteriovenous fistula. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3259. [PMID: 31483945 DOI: 10.1002/cnm.3259] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 07/17/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
Areas of disturbed shear that develop following arteriovenous fistula (AVF) creation are believed to trigger the onset of intimal hyperplasia (IH), leading to AVF dysfunction. The presence of helical flow can suppress the flow disturbances that lead to disturbed shear in other areas of the vasculature. However, the relationship between helical flow and disturbed shear remains unevaluated in AVF. In this study, computational fluid dynamics (CFD) is used to evaluate the relationship between geometry, helical flow, and disturbed shear in parameterised models of an AVF characterised by four different anastomosis angles. The AVF models with a small anastomosis angle demonstrate the lowest distribution of low/oscillating shear and are characterised by a high helical intensity coupled with a strong balance between helical structures. Contrastingly, the models with a large anastomosis angle experience the least amount of high shear, multidirectional shear, as well as spatial and temporal gradients of shear. Furthermore, the intensity of helical flow correlates strongly with curvature (r = 0.73, P < .001), whereas it is strongly and inversely associated with taper (r = -0.87, P < .001). In summary, a flow field dominated by a high helical intensity coupled with a strong balance between helical structures can suppress exposure to low/oscillating shear but is ineffective when it comes to other types of shear. This highlights the clinical potential of helical flow as a diagnostic marker of exposure to low/oscillating shear, as helical flow can be identified in vivo with the use of ultrasound imaging.
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Affiliation(s)
- Connor V Cunnane
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Eoghan M Cunnane
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Daniel T Moran
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Michael T Walsh
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
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34
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Quicken S, de Bruin Y, Mees B, Tordoir J, Delhaas T, Huberts W. Computational study on the haemodynamic and mechanical performance of electrospun polyurethane dialysis grafts. Biomech Model Mechanobiol 2019; 19:713-722. [PMID: 31679093 PMCID: PMC7105427 DOI: 10.1007/s10237-019-01242-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 10/18/2019] [Indexed: 11/29/2022]
Abstract
Compliance mismatch between an arteriovenous dialysis graft (AVG) and the connected vein is believed to result in disturbed haemodynamics around the graft–vein anastomosis and increased mechanical loading of the vein. Both phenomena are associated with neointimal hyperplasia development, which is the main reason for AVG patency loss. In this study, we use a patient-specific fluid structure interaction AVG model to assess whether AVG haemodynamics and mechanical loading can be optimised by using novel electrospun polyurethane (ePU) grafts, since their compliance can be better tuned to match that of the native veins, compared to gold standard, expanded polytetrafluoroethylene (ePTFE) grafts. It was observed that the magnitude of flow disturbances in the vein and the size of anastomotic areas exposed to highly oscillatory shear (\documentclass[12pt]{minimal}
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\begin{document}$$\hbox {OSI} >0.25$$\end{document}OSI>0.25) and very high wall shear stress (\documentclass[12pt]{minimal}
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\begin{document}$$>40 \hbox { Pa}$$\end{document}>40Pa) were largest for the ePTFE graft. Median strain and von Mises stress in the vein were similar for both graft types, whereas highest stress and strain were observed in the anastomosis of the ePU graft. Since haemodynamics were most favourable for the ePU graft simulation, AVG longevity might be improved by the use of ePU grafts.
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Affiliation(s)
- Sjeng Quicken
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands
| | - Yeshi de Bruin
- Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Barend Mees
- Department of Vascular Surgery, Maastricht University Medical Centre, PO Box 5800, 6229 HX, Maastricht, The Netherlands
| | - Jan Tordoir
- Department of Vascular Surgery, Maastricht University Medical Centre, PO Box 5800, 6229 HX, Maastricht, The Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands
| | - Wouter Huberts
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, 6223ER, Maastricht, The Netherlands.
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35
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Franzoni M, O'Connor DT, Marcar L, Power D, Moloney MA, Kavanagh EG, Leask RL, Nolan J, Kiely PA, Walsh MT. The Presence of a High Peak Feature Within Low-Average Shear Stimuli Induces Quiescence in Venous Endothelial Cells. Ann Biomed Eng 2019; 48:582-594. [PMID: 31555984 DOI: 10.1007/s10439-019-02371-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 09/18/2019] [Indexed: 11/24/2022]
Abstract
Wall shear stress (WSS) is an important stimulus in vascular remodelling and vascular lesion development. The current methods to assess and predict the risk associated with specific unsteady WSS consider the WSS mean values or the presence of reverse phases described by the oscillatory shear index. Recent evidence has shown that the accuracy of these methods is limited, especially with respect to the venous environment. Unsteady WSS are characterised by several features that may individually affect endothelial cells. Consequently, we assessed the effects of averaged WSS (TAWSS), temporal WSS gradient (TWSSG), maximum WSS (WSS peak) and reverse phase (OSI) by applying different WSS profiles to venous EC in-vitro, using a real-time controlled cone-and-plate cell-shearing device for 24 h. We found that TWSSG and WSS peak affect cell elongation and alignment respectively. We also found that the WSS waveforms with a peak of 1.5 Pa or higher significantly correlate with the induction of a protective phenotype. Cell phenotype induced by these high peak waveforms does not correlate to what is predicted by the hemodynamic indices currently used. The definition of reliable hemodynamic indices can be used to inform the computational models aimed at estimating the hemodynamic effects on vascular remodelling.
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Affiliation(s)
- M Franzoni
- School of Engineering, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland.,Health Research Institute, University of Limerick, Limerick, Ireland
| | - D T O'Connor
- School of Engineering, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland.,Health Research Institute, University of Limerick, Limerick, Ireland
| | - L Marcar
- School of Engineering, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland
| | - D Power
- Health Research Institute, University of Limerick, Limerick, Ireland.,Department of Vascular Surgery, University Hospital Limerick, Limerick, Ireland
| | - M A Moloney
- Health Research Institute, University of Limerick, Limerick, Ireland.,Department of Vascular Surgery, University Hospital Limerick, Limerick, Ireland
| | - E G Kavanagh
- Health Research Institute, University of Limerick, Limerick, Ireland.,Department of Vascular Surgery, University Hospital Limerick, Limerick, Ireland
| | - R L Leask
- Department of Chemical Engineering, McGill University, Montreal, Canada
| | - J Nolan
- Health Research Institute, University of Limerick, Limerick, Ireland.,Graduate Entry Medical School, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland
| | - P A Kiely
- Health Research Institute, University of Limerick, Limerick, Ireland.,Graduate Entry Medical School, Faculty of Education and Health Sciences, University of Limerick, Limerick, Ireland
| | - M T Walsh
- School of Engineering, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland. .,Health Research Institute, University of Limerick, Limerick, Ireland.
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36
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Walsh MT, Moore JE. Editorial: Special Issue on Vascular Access : Towards Improving Vascular Access. Cardiovasc Eng Technol 2018; 8:237-239. [PMID: 28795379 DOI: 10.1007/s13239-017-0326-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Michael T Walsh
- Health Research Institute, Bernal Institute, School of Engineering, University of Limerick, Limerick, Ireland.
| | - James E Moore
- Department of Bioengineering, Imperial College London, London, SW7 2AZ, UK
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37
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Tzchori I, Falah M, Shteynberg D, Levin Ashkenazi D, Loberman Z, Perry L, Flugelman MY. Improved Patency of ePTFE Grafts as a Hemodialysis Access Site by Seeding Autologous Endothelial Cells Expressing Fibulin-5 and VEGF. Mol Ther 2018; 26:1660-1668. [PMID: 29703700 DOI: 10.1016/j.ymthe.2018.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 04/01/2018] [Accepted: 04/01/2018] [Indexed: 11/28/2022] Open
Abstract
Small caliber synthetic vascular grafts used for dialysis access sites have high failure rates due to neointima formation and thrombosis. Seeding synthetic grafts with endothelial cells (ECs) provides a biocompatible surface that may prevent graft failure. We tested the use of ePTFE grafts seeded with autologous ECs expressing fibulin-5 and vascular endothelial growth factor (VEGF), as a dialysis access site in a porcine model. We connected the carotid arteries and jugular veins of 12 miniature pigs using 7-mm ePTFE grafts; five grafts were seeded with autologous venous ECs modified to express fibulin-5 and VEGF, and seven unseeded grafts were implanted at the same location and served as controls. At 6 months, after completion of angiography, the carotid arteries and jugular veins with the connecting grafts were excised and fixed. Autologous EC isolation and transduction and graft seeding were successful in all animals. At 3 months, 4 of 5 seeded grafts and 3 of 7 control grafts were patent. At 6 months, 4 of 5 (80%) seeded grafts and only 2 of 7 (29%) control grafts were patent. Seeding ePTFE vascular grafts with genetically modified ECs improved long term small caliber graft patency. The biosynthetic grafts offer a novel therapeutic modality for vascular access in hemodialysis.
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Affiliation(s)
- Itai Tzchori
- Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; VESSL Therapeutics Ltd., Haifa, Israel
| | - Mizied Falah
- Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; VESSL Therapeutics Ltd., Haifa, Israel
| | - Denis Shteynberg
- Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; VESSL Therapeutics Ltd., Haifa, Israel
| | | | - Zeev Loberman
- Rappaport Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Luba Perry
- Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel
| | - Moshe Y Flugelman
- Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, Haifa, Israel; VESSL Therapeutics Ltd., Haifa, Israel; Rappaport Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel.
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38
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A validated patient-specific FSI model for vascular access in haemodialysis. Biomech Model Mechanobiol 2017; 17:479-497. [DOI: 10.1007/s10237-017-0973-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 10/26/2017] [Indexed: 11/26/2022]
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39
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Uțu D, Pantea S, Duicu OM, Muntean DM, Sturza A. Contribution of monoamine oxidases to vascular oxidative stress in patients with end-stage renal disease requiring hemodialysis. Can J Physiol Pharmacol 2017; 95:1383-1388. [PMID: 28753408 DOI: 10.1139/cjpp-2017-0067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Arteriovenous fistula (AVF) is the "lifeline" for patients with end-stage renal disease (ESRD) undergoing hemodialysis. AVF maturation failure is a poorly understood process, one of the contributors being endothelial dysfunction due to oxidative stress. Monoamine oxidases (MAOs) A and B were recently identified as novel sources of vascular oxidative stress. The aim of the present study was to assess the contribution of MAOs to the endothelial dysfunction in patients with ESDR with indication of hemodialysis. Fragments of brachial artery collaterals were harvested from ESRD patients during the surgical procedure aimed at creating the vascular access in the cubital fossa. The effect of increasing concentrations (10, 30, 100 μmol/L) of the irreversible MAO-A inhibitor, clorgyline, and MAO-B inhibitor, selegiline, on endothelial-dependent relaxation (EDR) in response to cumulative doses of acetylcholine was studied in isolated phenylephrine-preconstricted vascular rings. Hydrogen peroxide (H2O2) production was assessed using ferrous oxidation xylenol orange assay. We showed that incubation of brachial rings with MAO inhibitors significantly improved EDR and attenuated H2O2 generation in patients with ESRD. MAO-related oxidative stress might contribute to the primary dysfunction/non-maturation of the AVF and MAO inhibitors could improve maturation and long-term patency of the vascular access in dialysis patients.
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Affiliation(s)
- Diana Uțu
- a Department of Pathophysiology, "Victor Babeş" University of Medicine and Pharmacy, Timişoara 300041, Romania
| | - Stelian Pantea
- b Department of Surgery II, "Victor Babeş" University of Medicine and Pharmacy, Timişoara, Romania
| | - Oana M Duicu
- a Department of Pathophysiology, "Victor Babeş" University of Medicine and Pharmacy, Timişoara 300041, Romania.,c Center for Translational Research and Systems Medicine, "Victor Babeş" University of Medicine and Pharmacy, Timişoara, Romania
| | - Danina M Muntean
- a Department of Pathophysiology, "Victor Babeş" University of Medicine and Pharmacy, Timişoara 300041, Romania.,c Center for Translational Research and Systems Medicine, "Victor Babeş" University of Medicine and Pharmacy, Timişoara, Romania
| | - Adrian Sturza
- a Department of Pathophysiology, "Victor Babeş" University of Medicine and Pharmacy, Timişoara 300041, Romania.,c Center for Translational Research and Systems Medicine, "Victor Babeş" University of Medicine and Pharmacy, Timişoara, Romania
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40
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Wish JB, Moe SM. Moving Beyond the Assumed: Improving Fistula Success Rates. J Am Soc Nephrol 2017; 28:2827-2829. [PMID: 28733368 DOI: 10.1681/asn.2017060663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Jay B Wish
- Division of Nephrology, Department of Medicine, Indiana University, and
| | - Sharon M Moe
- Division of Nephrology, Department of Medicine, Indiana University, and .,Roudebush Veterans Administration Medical Center, Indianapolis, Indiana
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41
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Ene-Iordache B, Remuzzi A. Blood Flow in Idealized Vascular Access for Hemodialysis: A Review of Computational Studies. Cardiovasc Eng Technol 2017; 8:295-312. [PMID: 28664239 DOI: 10.1007/s13239-017-0318-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 06/26/2017] [Indexed: 10/19/2022]
Abstract
Although our understanding of the failure mechanism of vascular access for hemodialysis has increased substantially, this knowledge has not translated into successful therapies. Despite advances in technology, it is recognized that vascular access is difficult to maintain, due to complications such as intimal hyperplasia. Computational studies have been used to estimate hemodynamic changes induced by vascular access creation. Due to the heterogeneity of patient-specific geometries, and difficulties with obtaining reliable models of access vessels, idealized models were often employed. In this review we analyze the knowledge gained with the use of computational such simplified models. A review of the literature was conducted, considering studies employing a computational fluid dynamics approach to gain insights into the flow field phenotype that develops in idealized models of vascular access. Several important discoveries have originated from idealized model studies, including the detrimental role of disturbed flow and turbulent flow, and the beneficial role of spiral flow in intimal hyperplasia. The general flow phenotype was consistent among studies, but findings were not treated homogeneously since they paralleled achievements in cardiovascular biomechanics which spanned over the last two decades. Computational studies in idealized models are important for studying local blood flow features and evaluating new concepts that may improve the patency of vascular access for hemodialysis. For future studies we strongly recommend numerical modelling targeted at accurately characterizing turbulent flows and multidirectional wall shear disturbances.
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Affiliation(s)
- Bogdan Ene-Iordache
- Laboratory of Biomedical Technologies, Clinical Research Center for Rare Diseases Aldo e Cele Daccò, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi 3, 24020, Ranica, BG, Italy.
| | - Andrea Remuzzi
- Laboratory of Biomedical Technologies, Clinical Research Center for Rare Diseases Aldo e Cele Daccò, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi 3, 24020, Ranica, BG, Italy.,Department of Management, Information and Production and Engineering, University of Bergamo, Dalmine, BG, Italy
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42
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Aneurysms in Vascular Access: State of the Art and Future Developments. J Vasc Access 2017; 18:464-472. [DOI: 10.5301/jva.5000828] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2017] [Indexed: 11/20/2022] Open
Abstract
A master class was held at the Vascular Access at Charing Cross (VA@CX2017) conference in April 2017 with invited experts and active audience participation to discuss arteriovenous (AV) vascular access aneurysms, a serious and common complication of vascular access (VA). The natural history of aneurysms in VA is poorly defined, and although classifications exist they are not uniformly applied in studies or clinical practice. True and pseudo aneurysms of AV access occur. Whilst an AV fistula by definition is an abnormal dilatation of a blood vessel, an agreed definition of 18 mm, or 3 times accepted maturation diameter, is proposed. The mechanism of aneurysmal dilatation is unknown but appears to be a combination of excessive external remodeling, wall changes due to injury, and obstruction of outflow. Diagnosis of AV aneurysms is based on physical examination and ultrasound. Venography and cross-sectional imaging may assist and be required for the investigation of outflow stenosis. Treatment of pseudo aneurysms and true aneurysms of VA (AVA) is not evidence-based, but relies on clinical experience and available facilities. In many AVA, a conservative approach with surveillance is suitable, although intervals and modalities are unclear. Avoidance of rupture is imperative and preemptive treatment should aim for access preservation, ideally with avoidance of prosthetic materials. Different techniques of aneurysmorrhaphy are described with good results in published series. Although endovascular approaches and stenting are described with good short-term results, issues with cannulation of stented areas occur and, while possible, this is not recommended, and long-term access revision is recommended.
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