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Szafron JM, Heng EE, Boyd J, Humphrey JD, Marsden AL. Hemodynamics and Wall Mechanics of Vascular Graft Failure. Arterioscler Thromb Vasc Biol 2024; 44:1065-1085. [PMID: 38572650 PMCID: PMC11043008 DOI: 10.1161/atvbaha.123.318239] [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: 09/04/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.
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Affiliation(s)
- Jason M Szafron
- Departments of Pediatrics (J.M.S., A.L.M.), Stanford University, CA
| | - Elbert E Heng
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jack Boyd
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT (J.D.H.)
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2
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Bozzetto M, Remuzzi A, Valen-Sendstad K. Flow-induced high frequency vascular wall vibrations in an arteriovenous fistula: a specific stimulus for stenosis development? Phys Eng Sci Med 2024; 47:187-197. [PMID: 38157188 DOI: 10.1007/s13246-023-01355-z] [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: 05/10/2023] [Accepted: 11/12/2023] [Indexed: 01/03/2024]
Abstract
Hemodialysis is the lifeline for nearly three million end stage renal disease patients worldwide. Native arteriovenous fistula (AVF) is the preferred vascular access, but 40% fail within 1 year. We recently demonstrated that AVFs harbour transitional flows and the goal of the present study was to investigate whether the associated high-frequency pressure fluctuations could promote vibrations within the vascular wall. We acquired MRI images and flow rates immediately after surgery in one patient and generated a 3D patient-specific model. High-fidelity fluid structure interaction simulations revealed the presence of wall vibrations in distinct frequency bands up to 200 Hz and amplitude of 200 μm. A sensitivity analysis to assess the impact of flow rates, and vascular wall stiffness and thickness, changes that typically occur during AVF maturation, confirmed the robustness of the results. Interestingly, the vibrations were always predominant at the anastomosis floor and on the inner venous side, which correlates with typical stenotic regions. As studies seeking to correlate aberrant stresses and vascular remodelling have been largely inconclusive, the focal colocalization between vibrations and stenosis may suggest an unknown mechanobiological process between high-frequency mechanical stresses within the vascular wall and adverse vascular remodelling.
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Affiliation(s)
- Michela Bozzetto
- Bioengineering Department, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Ranica, BG, Italy
| | - Andrea Remuzzi
- Department of Management Information and Production Engineering, University of Bergamo, Via G.B. Marconi 5, Dalmine, BG, Italy.
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Bartlett M, Bonfanti M, Diaz-Zuccarini V, Tsui J. Computationally Enhanced, Haemodynamic Case Study of Neointimal Hyperplasia Development in a Dialysis Access Fistula. Rev Cardiovasc Med 2024; 25:35. [PMID: 39077669 PMCID: PMC11262387 DOI: 10.31083/j.rcm2501035] [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: 12/29/2022] [Revised: 11/17/2023] [Accepted: 11/21/2023] [Indexed: 07/31/2024] Open
Abstract
Background Oscillatory wall shear stress and related metrics have been identified as potential predictors of dialysis access outcomes; however, the absence of a simple non-invasive method for measuring these haemodynamic forces has been prohibitive to their adoption into routine clinical practice. We present a computationally enhanced, single patient case study, offering a unique insight into the haemodynamic environment surrounding the development of flow limiting neointimal hyperplasia within the efferent vein of a previously functional arteriovenous fistula (AVF). Methods Computational fluid dynamics (CFD) simulations were used to create a quantitative map of oscillatory shear stress as well as enabling visualisation of streamline patterns within the AVF. CFD data was compared to ultrasound-based turbulence quantification and examined alongside structural and functional changes in the access site over time. Results This work further supports the notion that flow limiting neointimal hyperplasia development in vascular access fistulae, occurs in response to oscillatory wall shear stress, and provides proof of concept for the idea that non-invasive ultrasound turbulence quantification tools could play a role in predicting vascular access outcomes. Conclusions In addition to providing insight into the haemodynamic environment surrounding the development of flow limiting neointimal hyperplasia, we hope that this paper will promote discussion and further thinking about how our learnings from in-silico studies can be incorporated into clinical practice through novel uses of existing diagnostic tools.
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Affiliation(s)
- Matthew Bartlett
- Division of Surgery & Interventional Science, University College London, Royal Free Campus, NW3 2QG London, UK
- Department of Vascular Surgery, Royal Free London NHS Foundation Trust, NW3 2QG London, UK
| | - Mirko Bonfanti
- Department of Mechanical Engineering, University College London, WC1E 7JE London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, W1W 7TS London, UK
| | - Vanessa Diaz-Zuccarini
- Department of Mechanical Engineering, University College London, WC1E 7JE London, UK
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), Department of Medical Physics and Biomedical Engineering, University College London, W1W 7TS London, UK
| | - Janice Tsui
- Division of Surgery & Interventional Science, University College London, Royal Free Campus, NW3 2QG London, UK
- Department of Vascular Surgery, Royal Free London NHS Foundation Trust, NW3 2QG London, UK
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4
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Bozzetto M, Soliveri L, Poloni S, Brambilla P, Curtò D, Condemi GC, Cefalì P, Spina I, Villa A, Caroli A, Remuzzi A. Arteriovenous fistula creation with VasQ TM device: A feasibility study to reveal hemodynamic implications. J Vasc Access 2024; 25:60-70. [PMID: 35451351 PMCID: PMC10845834 DOI: 10.1177/11297298221087160] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/20/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Arteriovenous fistula (AVF) is the preferred vascular access (VA) for hemodialysis, but it is still affected by high non-maturation and early failure rates due to stenosis development. Increasing evidence suggests that the presence of turbulent-like flow may play a key role, therefore, to stabilize the flow in the venous segment, an external support device (VasQTM) has been designed. The aim of this study was to provide preliminary evidence of VasQTM impact on AVF hemodynamics as compared to AVFs created with conventional surgery. METHODS In this pilot single-center prospective randomized study six patients were enrolled, three in the VasQ group and three in the control group. Contrast-free magnetic resonance imaging (MRI) scans were acquired at 3 days, 3 months and 1 year after AVF surgery and were used to generate 3D patient-specific models. Computational fluid dynamic (CFD) simulations were performed using pimpleFoam, imposing patient-specific flow waveforms derived from ultrasound (US) examinations at the inlet of the proximal and distal artery, and a traction-free condition at the venous outflow. Morphologic and hemodynamic changes occurring over time were compared between VasQ and control AVFs. RESULTS Our MRI protocol provided high-quality images suitable for reliable segmentation and reconstruction of patient-specific 3D models of AVFs at all three timepoints in four out of six patients. The VasQTM device maintained the angle between the artery and the vein almost unchanged over time, with a more stable flow in the AVFs supported by the device. In contrast, one of the AVFs of the control group evolved to an extreme dilatation of the vein and highly disturbed flow, while the other developed a stenosis in the juxta-anastomotic region. CONCLUSIONS This study demonstrated the feasibility of characterizing the morphological and hemodynamic changes occurring over time in AVFs created using the VasQTM device and provided preliminary evidence of the potential hemodynamic benefits of its use.
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Affiliation(s)
- Michela Bozzetto
- Department of Engineering and Applied Sciences, University of Bergamo, Italy
| | - Luca Soliveri
- Department of Biomedical Engineering - Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Sofia Poloni
- Department of Biomedical Engineering - Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Paolo Brambilla
- Diagnostic Radiology, Papa Giovanni XXIII Hospital, University of Milano-Bicocca, Milan, Italy
| | - Diego Curtò
- Unit of Nephrology and Dialysis, ASST Ospedale Papa Giovanni XXIII, Bergamo, Italy
| | | | - Pietro Cefalì
- Unit of Vascular Surgery, ASST Ospedale Papa Giovanni XXIII, Bergamo, Italy
| | - Irene Spina
- Unit of Vascular Surgery, ASST Ospedale Papa Giovanni XXIII, Bergamo, Italy
| | - Alessandro Villa
- Department of Renal Medicine, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Anna Caroli
- Department of Biomedical Engineering - Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Andrea Remuzzi
- Department of Management, Information and Production Engineering, University of Bergamo, Italy
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5
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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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Soliveri L, Bozzetto M, Brambilla P, Caroli A, Remuzzi A. Hemodynamics in AVF over time: A protective role of vascular remodeling toward flow stabilization. Int J Artif Organs 2023; 46:547-554. [PMID: 37753863 PMCID: PMC10629258 DOI: 10.1177/03913988231191960] [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: 05/17/2023] [Accepted: 07/20/2023] [Indexed: 09/28/2023]
Abstract
The mechanisms underlying vascular stenosis formation in the arteriovenous fistula (AVF) for hemodialysis (HD) remain mostly unknown. Several computational fluid dynamics (CFD) studies have suggested a potential role for unsteady flow in inducing intimal hyperplasia and AVF stenosis, but the majority of these observations have been limited to a single time point after surgical creation. The aim of the present study was to investigate the relation between hemodynamic conditions and AVF vascular remodeling through a CFD longitudinal study. Non contrast-enhanced MR images and Doppler Ultrasound (US) examinations were acquired at 3 days, 40 days, 6 months, 1 year, and 1.5 years after surgery in a 72-year male referred for native radio-cephalic AVF. Three-dimensional AVF models were generated and high fidelity CFD simulations were performed using pimpleFoam, setting patient-specific boundary conditions derived from US. Morphological and hemodynamic changes over time were then analyzed. Analysis of vessel morphology and hemodynamics during follow-up showed that the AVF had a successful maturation process, characterized by a massive arterial and venous dilatation within the 6 months after surgery, a corresponding increase in blood flow volume and important flow instabilities. Between 6 months and 1 year, a stenosis developed in the juxta-anastomotic vein and caused AVF failure at 1.5 years. The development of stenosis was paralleled by the regularization of blood flow velocity pattern and consequent decrease in the near-wall disturbed flow metrics. These results suggest that development of intimal hyperplasia and vessel stenosis, triggered by unsteady flow, could be the result of vascular inward remodeling toward regularization of turbulent-like flow.
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Affiliation(s)
- Luca Soliveri
- Department of Biomedical Engineering, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Michela Bozzetto
- Department of Biomedical Engineering, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Paolo Brambilla
- Diagnostic Radiology, Papa Giovanni XXIII Hospital, Bergamo, Italy
- School of Medicine, University of Milano-Bicocca, Milan, Italy
| | - Anna Caroli
- Department of Biomedical Engineering, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Andrea Remuzzi
- Department of Management, Information and Production Engineering, University of Bergamo, Italy
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Idrees N, Haroon S, Zhang Y, Mangio JC, Siracuse JJ, Francis JM, Ganguli S, Daly K, Diamond M, Vilvendhan R, Cabral H, Dember LM, Farber A, Kolachalama VB, Chitalia VC. Contrast Venography Versus Intravenous Ultrasound in Hemodialysis Arteriovenous Access Dysfunction. Kidney Int Rep 2023; 8:1887-1891. [PMID: 37705907 PMCID: PMC10496077 DOI: 10.1016/j.ekir.2023.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 05/16/2023] [Accepted: 06/12/2023] [Indexed: 09/15/2023] Open
Affiliation(s)
- Najia Idrees
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Veterans Affairs Boston Healthcare System, Boston MA 02118, USA
| | - Samir Haroon
- Section of Interventional Radiology, Department of Radiology, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Yichi Zhang
- Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Joanna Crisa Mangio
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jeffrey J. Siracuse
- Division of Vascular and Endovascular Surgery, Department of Surgery, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jean M. Francis
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Suvranu Ganguli
- Section of Interventional Radiology, Department of Radiology, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Kevin Daly
- Section of Interventional Radiology, Department of Radiology, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Matthew Diamond
- Section of Interventional Radiology, Department of Radiology, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Rajendran Vilvendhan
- Department of Radiology, Interventional Radiology, Lahey Hospital and Medical Center, Beth Israel Lahey Health, Harvard Medical School, Boston, Massachusetts, USA
| | - Howard Cabral
- Department of Biostatistics, School of Public Health, Boston University, Boston, Massachusetts, USA
| | - Laura M. Dember
- Renal-Electrolyte and Hypertension Division, Department of Medicine; Center for Clinical Epidemiology and Biostatistics; and Department of Biostatistics, Epidemiology and Informatics; Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Alik Farber
- Division of Vascular and Endovascular Surgery, Department of Surgery, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Vijaya B. Kolachalama
- Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
- Department of Computer Science and Faculty of Computing & Data Sciences, Boston University, Boston, Massachusetts, USA
| | - Vipul C. Chitalia
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
- Veterans Affairs Boston Healthcare System, Boston MA 02118, USA
- Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, 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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He Y, Tran-Son-Tay R, Berceli SA. Distinct Temporal Pattern of the Prediction of Lumen Remodeling of Lower Extremity Vein Bypass Grafts by Initial Local Hemodynamics. Ann Biomed Eng 2023; 51:296-307. [PMID: 35881266 DOI: 10.1007/s10439-022-03019-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/05/2022] [Indexed: 01/25/2023]
Abstract
We predicted human lower extremity vein bypass graft remodeling by hemodynamics. Computed tomography and duplex ultrasound scans of 55 patients were performed at 1 week and 1, 6, and 12 months post-implantation to obtain wall shear stress (WSS) and oscillatory shear index (OSI) at 1-mm intervals via computational fluid dynamics simulations. Graft remodeling was quantified by computed tomography-measured lumen diameter changes in the early (1 week-1 month), intermediate (1-6 months), and late (6-12 months) periods. Linear mixed-effect models were constructed to examine the overall relationship between remodeling and initial hemodynamics using the average data of all cross sections within the same graft. A significant association of graft remodeling with WSS (p < 0.001) and time (p = 0.001) was found; however, the effect size decreased with time (every 2.7 dyne/cm2 increase of WSS was associated with a 0.39, 0.35, 0.002 mm diameter increase in the three periods, respectively). The association of remodeling with OSI was significant only in the intermediate period (every 0.1 increase of OSI was associated with a 0.25 mm lumen diameter decrease, p = 0.004). Therefore, the association of graft lumen remodeling with local hemodynamics has a distinct temporal pattern; WSS and OSI are predictive of remodeling only in certain postoperative periods.
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Affiliation(s)
- Yong He
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, University of Florida, PO Box 100128, Gainesville, FL, 32610-0286, USA. .,The Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, USA.
| | - Roger Tran-Son-Tay
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Scott A Berceli
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, University of Florida, PO Box 100128, Gainesville, FL, 32610-0286, USA.,The Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, USA
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10
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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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11
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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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12
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A longitudinal study of the arterio-venous fistula maturation of a single patient over 15 weeks. Biomech Model Mechanobiol 2022; 21:1217-1232. [PMID: 35614372 PMCID: PMC9283179 DOI: 10.1007/s10237-022-01586-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 04/12/2022] [Indexed: 11/06/2022]
Abstract
Arterio-venous fistula creation is the preferred vascular access for haemodialysis, but has a large failure rate in the maturation period. Previous research, considering the remodelling mechanisms for failure-to-mature patients, has been limited by obtaining the patient-specific boundary conditions at only a few points in the patient history. Here, a non-invasive imaging system was used to reconstruct the three-dimensional vasculature, and computational fluid dynamics was used to analyse the haemodynamics for one patient over 15 weeks. The analysis suggested evidence of a control mechanism, which adjusts the lumen diameter to keep the wall shear stress near constant in the proximal regions of the vein and artery. Additionally, the vein and artery were shown to remodel at different growth rates, and the blood flow rate also saw the largest increase within the first week. Wall shear stress at time of creation may be a useful indicator for successful AVF maturation.
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13
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He Y, Northrup H, Le H, Cheung AK, Berceli SA, Shiu YT. Medical Image-Based Computational Fluid Dynamics and Fluid-Structure Interaction Analysis in Vascular Diseases. Front Bioeng Biotechnol 2022; 10:855791. [PMID: 35573253 PMCID: PMC9091352 DOI: 10.3389/fbioe.2022.855791] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/08/2022] [Indexed: 01/17/2023] Open
Abstract
Hemodynamic factors, induced by pulsatile blood flow, play a crucial role in vascular health and diseases, such as the initiation and progression of atherosclerosis. Computational fluid dynamics, finite element analysis, and fluid-structure interaction simulations have been widely used to quantify detailed hemodynamic forces based on vascular images commonly obtained from computed tomography angiography, magnetic resonance imaging, ultrasound, and optical coherence tomography. In this review, we focus on methods for obtaining accurate hemodynamic factors that regulate the structure and function of vascular endothelial and smooth muscle cells. We describe the multiple steps and recent advances in a typical patient-specific simulation pipeline, including medical imaging, image processing, spatial discretization to generate computational mesh, setting up boundary conditions and solver parameters, visualization and extraction of hemodynamic factors, and statistical analysis. These steps have not been standardized and thus have unavoidable uncertainties that should be thoroughly evaluated. We also discuss the recent development of combining patient-specific models with machine-learning methods to obtain hemodynamic factors faster and cheaper than conventional methods. These critical advances widen the use of biomechanical simulation tools in the research and potential personalized care of vascular diseases.
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Affiliation(s)
- Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
| | - Hannah Northrup
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
| | - Ha Le
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, 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 Salt Lake City Healthcare System, Salt Lake City, UT, United States
| | - Scott A. Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, United States
- Vascular Surgery Section, Malcom Randall Veterans Affairs Medical Center, Gainesville, FL, United States
| | - Yan Tin Shiu
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, United States
- Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, UT, United States
- *Correspondence: Yan Tin Shiu,
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14
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Shembekar SN, Zodpe D, Padole P. Prediction of the anastomosis angle of arteriovenous fistula in hemodialysis to standardize the surgical technique. Biomed Mater Eng 2022; 33:423-436. [DOI: 10.3233/bme-211389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Arteriovenous fistula (AVF) is the preferred route of vascular access in hemodialysis. The primary reason of fistula failure is Intimal hyperplasia (IH), which leads to stenosis. Wall shear stress (WSS) and disturbed flow are the critical parameters in the formation of IH. OBJECTIVE: The primary goal of this study is to explore the influence of anastomosis angle on WSS and venous outflow rate, as well as to find the ideal angle of anastomosis for AVF to standardize surgical technique. METHODS: Three-dimensional idealized geometries of end-to-side type AVF for the five various angles of anastomosis are considered in this study. The WSS, blood flow rate at the venous outlet for non-Newtonian, pulsatile blood flow are calculated using a numerical simulation technique. RESULTS: The WSS is higher at 75° compared to other angles and least at 45° for pulsating arterial inflows. The WSS is moderate at 30°, 60° and 90°. On the arterial bed and outer wall of the vein, immediately after the anastomosis, the recirculation zone is observed. At an angle of 45° and 90° anastomosis, the outflow rate is greater at distal venous end. CONCLUSIONS: If one believes that high wall shear stress causes IH within the AVF, the results suggest that the AVF should be formed at a 45° angle to avoid IH. However, if one believes that low wall shear stress causes IH within the AVF, the results suggest that AVF should be formed at either 30° or 75° to avoid IH. The findings spotlight the importance of anastomosis angle in determining AVF hemodynamics.
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Affiliation(s)
| | - D.B. Zodpe
- , Visvesvaraya National Institute of Technology, , , India
| | - P.M. Padole
- , Visvesvaraya National Institute of Technology, , , India
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15
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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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16
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Effect of Subject-Specific, Spatially Reduced, and Idealized Boundary Conditions on the Predicted Hemodynamic Environment in the Murine Aorta. Ann Biomed Eng 2021; 49:3255-3266. [PMID: 34528150 DOI: 10.1007/s10439-021-02851-7] [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: 06/28/2020] [Accepted: 08/06/2021] [Indexed: 10/20/2022]
Abstract
Mouse models of atherosclerosis have become effective resources to study atherogenesis, including the relationship between hemodynamics and lesion development. Computational methods aid the prediction of the in vivo hemodynamic environment in the mouse vasculature, but careful selection of inflow and outflow boundary conditions (BCs) is warranted to promote model accuracy. Herein, we investigated the impact of animal-specific versus reduced/idealized flow boundary conditions on predicted blood flow patterns in the mouse thoracic aorta. Blood velocities were measured in the aortic root, arch branch vessel, and descending aorta in ApoE-/- mice using phase-contrast MRI. Computational geometries were derived from micro-CT imaging and combinations of high-fidelity or reduced/idealized MR-derived BCs were applied to predict the bulk flow field and hemodynamic metrics (e.g., wall shear stress, WSS; cross-flow index, CFI). Results demonstrate that pressure-free outlet BCs significantly overestimate outlet flow rates as compared to measured values. When compared to models that incorporate 3-component inlet velocity data [[Formula: see text]] and time-varying outlet mass flow splits [[Formula: see text]] (i.e., high-fidelity model), neglecting in-plane inlet velocity components (i.e., [Formula: see text])) leads to errors in WSS and CFI values ranging from 10 to 30% across the model domain whereas the application of a steady outlet mass flow splits results in negligible differences in these hemodynamics metrics. This investigation highlights that 3-component inlet velocity data and at least steady mass flow splits are required for accurate predictions of flow patterns in the mouse thoracic aorta.
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17
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Kashyap NK, Danish AF, Magatapalli K, Dantis K. Brief overview of surgical aspect of autologous arterio-venous fistula for dialysis access. Asian Cardiovasc Thorac Ann 2021; 30:2184923211029496. [PMID: 34233499 DOI: 10.1177/02184923211029496] [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: 11/15/2022]
Abstract
Patients with the end-stage renal disease require renal replacement therapy in renal transplant, peritoneal dialysis, and intermittent hemodialysis. Hemodialysis remains the primary modality for renal replacement therapy. Excellent vascular access is a mainstay for performing hemodialysis. Here we present a brief review of the various surgical aspects of AV fistula creation. Preoperative physical examination and judicious use of the imaging modalities to define the artery and venous mapping provide a good outcome of the fistula formation. Surgical creation of RC-AVF is preferred for the end-stage renal disease patient. The end-to-side anastomosis between the radial artery and cephalic vein has shown very good results.
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Affiliation(s)
- Nitin K Kashyap
- Department of Cardiovascular and Thoracic Surgery, All India Institute of Medical Sciences Raipur, Raipur, India
| | - Ahmad F Danish
- Department of Cardiovascular and Thoracic Surgery, All India Institute of Medical Sciences Raipur, Raipur, India
| | - Kishan Magatapalli
- Department of Cardiovascular and Thoracic Surgery, All India Institute of Medical Sciences Raipur, Raipur, India
| | - Klein Dantis
- Department of Cardiovascular and Thoracic Surgery, All India Institute of Medical Sciences Raipur, Raipur, India
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18
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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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19
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Taniguchi R, Ono S, Isaji T, Gorecka J, Lee SR, Matsubara Y, Yatsula B, Koizumi J, Nishibe T, Hoshina K, Dardik A. A mouse model of stenosis distal to an arteriovenous fistula recapitulates human central venous stenosis. JVS Vasc Sci 2020; 1:109-122. [PMID: 33543148 PMCID: PMC7857464 DOI: 10.1016/j.jvssci.2020.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Objective Central venous stenosis (CVS) is a major cause of arteriovenous fistula (AVF) failure. However, central veins are relatively inaccessible to study with conventional Doppler ultrasound methods. To understand mechanisms underlying AVF failure owing to CVS, an animal model was established that creates a stenosis distal to an AVF. We hypothesized that this mouse model will show comparable morphology and physiology to human CVS. Methods An aortocaval fistula was created between the distal aorta and inferior vena cava (IVC); a stenosis was then created distal to the fistula by partial IVC ligation. Sham-operated animals, AVF without venous stenosis, and venous stenosis without AVF were used as controls. Physiologic properties of the IVC, both upstream and downstream of the stenosis, or the corresponding sites in models without stenosis, were assessed with ultrasound examination on days 0 to 21. The spectral broadening index was measured to assess the degree of disturbed shear stress. The IVC was harvested at day 21 and specimens were analyzed with immunofluorescence. Results The IVC diameter of mice with an AVF and stenosis showed increased upstream (P = .013), but decreased downstream diameter (P = .001) compared with mice with an AVF but without a stenosis, at all postoperative times (days 3-21). IVC wall thickness increased in mice with an AVF, compared with IVC without an AVF (upstream of stenosis: 13.9 μm vs 11.0 μm vs 4.5 μm vs 3.9 μm; P = .020; downstream of stenosis: 6.0 μm vs 6.6 μm vs μm 4.5 μm vs 3.8 μm; P = .002; AVF with stenosis, AVF, stenosis, sham, respectively). AVF patency significantly decreased in mice with an AVF and stenosis by day 21 (50% vs 90%; P = .048). The IVC of mice with AVF and stenosis showed a venous waveform with pulsatility as well as enhanced velocity at and downstream of the stenosis; similar waveforms were observed in a human case of CVS. Downstream to the stenosis, the spectral broadening index was significantly higher compared with mice with AVF alone (1.06 vs 0.78; P = .011; day 21), and there was a trend towards less immunoreactivity of both Krüppel-like factor 2 and phosphorylated-endothelial nitric oxide synthase compared with mice with an AVF alone. Conclusions Partial IVC ligation distal to a mouse aortocaval fistula alters the fistula diameter and wall thickness, decreases patency, and increases distal disturbed flow compared with fistulae without a distal stenosis. Our mouse model of stenosis distal to an AVF may be a faithful representation of human CVS that shows similar morphology and physiology, including disturbed shear stress. A mouse model of venous stenosis distal to an arteriovenous fistula shows similar Doppler waveforms as those observed in a human case of central venous stenosis. These mice retain disturbed shear stress in the vein distal to the fistula, characterized by a sustained increase of the spectral broadening index and diminished expression of proteins upregulated by laminar shear stress. This novel mouse model will enable investigation of the physiology and downstream molecular pathways involved in central venous stenosis in humans.
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Affiliation(s)
- Ryosuke Taniguchi
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven.,Division of Vascular Surgery, The University of Tokyo, Bunkyo-ku, Tokyo
| | - Shun Ono
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven.,Department of Diagnostic Radiology, Tokai University School of Medicine, Isehara, Kanagawa
| | - Toshihiko Isaji
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven.,Division of Vascular Surgery, The University of Tokyo, Bunkyo-ku, Tokyo
| | - Jolanta Gorecka
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven
| | - Shin-Rong Lee
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven
| | - Yutaka Matsubara
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven.,Department of Surgery and Sciences, Kyushu University, Fukuoka
| | - Bogdan Yatsula
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven
| | - Jun Koizumi
- Department of Diagnostic Radiology, Tokai University School of Medicine, Isehara, Kanagawa
| | - Toshiya Nishibe
- Department of Cardiovascular Surgery, Tokyo Medical University, Shinjuku-ku, Tokyo
| | - Katsuyuki Hoshina
- Division of Vascular Surgery, The University of Tokyo, Bunkyo-ku, Tokyo
| | - Alan Dardik
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven.,Division of Vascular and Endovascular Surgery, Department of Surgery, Yale School of Medicine, New Haven.,Department of Surgery, VA Connecticut Healthcare Systems, West Haven
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20
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Yang CY, Li MC, Lan CW, Lee WJ, Lee CJ, Wu CH, Tang JM, Niu YY, Lin YP, Shiu YT, Cheung AK, Lee YHW, Lee OKS, Chien S, Tarng DC. The Anastomotic Angle of Hemodialysis Arteriovenous Fistula Is Associated With Flow Disturbance at the Venous Stenosis Location on Angiography. Front Bioeng Biotechnol 2020; 8:846. [PMID: 32793578 PMCID: PMC7390971 DOI: 10.3389/fbioe.2020.00846] [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: 04/22/2020] [Accepted: 06/30/2020] [Indexed: 12/14/2022] Open
Abstract
The juxta-anastomotic stenosis of an arteriovenous fistula (AVF) is a significant clinical problem in hemodialysis patients with no effective treatment. Previous studies of AV anastomotic angles on hemodynamics and vascular wall injury were based on computational fluid dynamics (CFD) simulations using standardized AVF geometry, not the real-world patient images. The present study is the first CFD study to use angiographic images with patient-specific outcome information, i.e., the exact location of the AVF stenotic lesion. We conducted the CFD analysis utilizing patient-specific AVF geometric models to investigate hemodynamic parameters at different locations of an AVF, and the association between hemodynamic parameters and the anastomotic angle, particularly at the stenotic location. We analyzed 27 patients who used radio-cephalic AVF for hemodialysis and received an angiographic examination for juxta-anastomotic stenosis. The three-dimensional geometrical model of each patient's AVF was built using the angiographic images, in which the shape and the anastomotic angle of the AVF were depicted. CFD simulations of AVF hemodynamics were conducted to obtain blood flow parameters at different locations of an AVF. We found that at the location of the stenotic lesion, the AV angle was significantly correlated with access flow disturbance (r = 0.739; p < 0.001) and flow velocity (r = 0.563; p = 0.002). Furthermore, the receiver operating characteristic (ROC) curve analysis revealed that the AV angle determines the lesion's flow disturbance with a high area under the curve value of 0.878. The ROC analysis also identified a cut-off value of the AV angle as 46.5°, above or below which the access flow disturbance was significantly different. By applying CFD analysis to real-world patient images, the present study provides evidence that an anastomotic angle wider than 46.5° might lead to disturbed flow generation, demonstrating a reference angle to adopt during the anastomosis surgery.
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Affiliation(s)
- Chih-Yu Yang
- Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
- Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- Stem Cell Research Center, National Yang-Ming University, Taipei, Taiwan
- Center for Intelligent Drug Systems and Smart Bio-devices (IDSB), Hsinchu, Taiwan
| | - Ming-Chia Li
- Center for Intelligent Drug Systems and Smart Bio-devices (IDSB), Hsinchu, Taiwan
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Chien-Wen Lan
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Wang-Jiun Lee
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Chen-Ju Lee
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Cheng-Hsueh Wu
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jing-Min Tang
- Department of Aerospace Engineering, Tamkang University, New Taipei City, Taiwan
| | - Yang-Yao Niu
- Department of Aerospace Engineering, Tamkang University, New Taipei City, Taiwan
| | - Yao-Ping Lin
- Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, University of Utah School of Medicine, Salt Lake City, UT, United States
- Veterans Affairs Medical Center, Salt Lake City, UT, United States
| | - Alfred K. Cheung
- Division of Nephrology and Hypertension, University of Utah School of Medicine, Salt Lake City, UT, United States
- Veterans Affairs Medical Center, Salt Lake City, UT, United States
| | - Yan-Hwa Wu Lee
- Center for Intelligent Drug Systems and Smart Bio-devices (IDSB), Hsinchu, Taiwan
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
| | - Oscar Kuang-Sheng Lee
- Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
- Stem Cell Research Center, National Yang-Ming University, Taipei, Taiwan
- Institute of Engineering in Medicine, University of California, San Diego, San Diego, CA, United States
| | - Shu Chien
- Institute of Engineering in Medicine, University of California, San Diego, San Diego, CA, United States
| | - Der-Cherng Tarng
- Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
- Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- Center for Intelligent Drug Systems and Smart Bio-devices (IDSB), Hsinchu, Taiwan
- Department of Biological Science and Technology, College of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan
- Department and Institute of Physiology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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21
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Hammes M, Cassel K, Boghosian M, Watson S, Funaki B, Coe F. A cohort study showing correspondence of low wall shear stress and cephalic arch stenosis in brachiocephalic arteriovenous fistula access. J Vasc Access 2020; 22:380-387. [PMID: 32693668 DOI: 10.1177/1129729820942048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND A brachiocephalic fistula is frequently placed for hemodialysis; unfortunately, cephalic arch stenosis commonly develops, leading to failure. We hypothesized that a contribution to brachiocephalic fistula failure is low wall shear stress resulting in neointimal hyperplasia leading to venous stenosis. The objective of this investigation is to determine correspondence of low wall shear stress and the development of cephalic arch stenosis. METHODS Forty subjects receiving hemodialysis with a primary brachiocephalic fistula access were followed from time of placement for 3 years or until cephalic arch stenosis. Venogram, Doppler, and viscosity were performed at time of fistula maturation, annually for 3 years or to time of cephalic arch stenosis. Computational hemodynamics modeling was performed to determine location and percent low wall shear stress in the arch. The relationship between wall shear stress at time of maturation and location of cephalic arch stenosis were estimated by correlating computational modeling and quadrant location of cephalic arch stenosis. RESULTS In total, 32 subjects developed cephalic arch stenosis with 26 displaying correspondence between location of low wall shear stress at time of maturation and subsequent cephalic arch stenosis, whereas 6 subjects did not (p = 0.0015). Most subjects with correspondence had low wall shear stress areas evident in greater than 20% of the arch (p = 0.0006). Low wall shear stress was associated with a higher risk of cephalic arch stenosis in the 23-to-45 age group (p = 0.0029). CONCLUSIONS The presence and magnitude of low wall shear stress in the cephalic arch is a factor associated with development of cephalic arch stenosis in patients with brachiocephalic fistula. Attenuation of low wall shear stress at time of maturation may help prevent the development of cephalic arch stenosis which is difficult to treat once it develops.
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Affiliation(s)
- Mary Hammes
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, IL, USA
| | - Kevin Cassel
- Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago, IL, USA
| | - Michael Boghosian
- Department of Mechanical, Materials and Aerospace Engineering, Illinois Institute of Technology, Chicago, IL, USA
| | | | - Brian Funaki
- Department of Radiology, University of Chicago, Chicago, IL, USA
| | - Frederic Coe
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, IL, USA
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22
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MacDonald CJ, Hellmuth R, Priba L, Murphy E, Gandy S, Matthew S, Ross R, Houston JG. Experimental Assessment of Two Non-Contrast MRI Sequences Used for Computational Fluid Dynamics: Investigation of Consistency Between Techniques. Cardiovasc Eng Technol 2020; 11:416-430. [PMID: 32613600 PMCID: PMC7385008 DOI: 10.1007/s13239-020-00473-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 06/20/2020] [Indexed: 11/05/2022]
Abstract
Purpose Recent studies have noted a degree of variance between the geometries segmented by different groups from 3D medical images that are used in computational fluid dynamics (CFD) simulations of patient-specific cardiovascular systems. The aim of this study was to determine if the applied sequence of magnetic resonance imaging (MRI) also introduced observable variance in CFD results. Methods Using a series of phantoms MR images of vessels of known diameter were assessed for the time-of-flight and multi-echo data image combination sequences. Following this, patient images of arterio-venous fistulas were acquired using the same sequences. Comparisons of geometry were made using the phantom and patient images, and of wall shear stress quantities using the CFD results from the patient images. Results Phantom images showed deviations in diameter between 0 and 15% between the sequences, depending on vessel diameter. Patient images showed different geometrical features such as narrowings that were not present on both sequences. Distributions of wall shear stress (WSS) quantities differed from simulations between the geometries obtained from the sequences. Conclusion In conclusion, choosing different MRI sequences resulted in slightly different geometries of the same anatomy, which led to compounded errors in WSS quantities from CFD simulation. Electronic supplementary material The online version of this article (10.1007/s13239-020-00473-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- C J MacDonald
- Imaging and Technology, University of Dundee, Dundee, UK
| | - R Hellmuth
- Vascular Flow Technologies LTD, Dundee, UK
| | - L Priba
- Medical Physics, NHS Tayside, Dundee, UK
| | - E Murphy
- Imaging and Technology, University of Dundee, Dundee, UK
| | - S Gandy
- Medical Physics, NHS Tayside, Dundee, UK
| | - S Matthew
- Imaging and Technology, University of Dundee, Dundee, UK
| | - R Ross
- Vascular Laboratory, NHS Tayside, Dundee, UK
| | - J G Houston
- Imaging and Technology, University of Dundee, Dundee, UK. .,Molecular and Clinical Medicine, School of Medicine, University of Dundee, Dundee, UK.
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23
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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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24
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Prouse G, Stella S, Vergara C, Quarteroni A, Engelberger S, Canevascini R, Giovannacci L. Computational Analysis of Turbulent Hemodynamics in Radiocephalic Arteriovenous Fistulas to Determine the Best Anastomotic Angles. Ann Vasc Surg 2020; 68:451-459. [PMID: 32278869 DOI: 10.1016/j.avsg.2020.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hemodynamics has been known to play a major role in the development of intimal hyperplasia leading to arteriovenous fistula failure. The goal of our study is to investigate the influence of different angles of side-to-end radiocephalic anastomosis on the hemodynamic parameters that promote intimal dysfunction and therefore intimal hyperplasia. METHODS Realistic three-dimensional meshes were reconstructed using ultrasound measurements from distal side-to-end radiocephalic fistulas. The velocity at the proximal and distal radial inflows and at specific locations along the anastomosis and cephalic vein was measured through duplex ultrasound performed by a single examiner. A computational parametric study, virtually changing the inner angle of anastomosis, was performed. For this purpose, we used advanced computational models that include suitable tools to capture the pulsatile and turbulent nature of the blood flow found in arteriovenous fistulas. The results were analyzed in terms of velocity fields, wall shear stress distribution, and oscillatory shear index. RESULTS Results show that the regions with high oscillatory shear index, which are more prone to the development of hyperplasia, are greater and progressively shift toward the anastomosis area and the proximal vein segment with the decrease of the inner angle of anastomosis. These results are specific to distal radiocephalic fistulas because they are subject to proximal and distal radial inflow. CONCLUSIONS The results of this study show that inner anastomosis angles approaching 60-70° seem to yield the best hemodynamic conditions for maturation and long-term patency of distal radiocephalic fistulas. Inner angles greater than 90°, representing the smooth loop technique, did not show a clear hemodynamic advantage.
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Affiliation(s)
- Giorgio Prouse
- Department of Surgery, Lugano Regional Hospital, Lugano, Switzerland.
| | - Simone Stella
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy
| | - Christian Vergara
- LABS, Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Milan, Italy
| | - Alfio Quarteroni
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy; Institute of Mathematics, Ecole Polytechnique, Federale de Lausanne, Lausanne, Switzerland
| | | | - Reto Canevascini
- Service of Angiology, Lugano Regional Hospital, Lugano, Switzerland
| | - Luca Giovannacci
- Department of Surgery, Lugano Regional Hospital, Lugano, Switzerland
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25
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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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26
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Tricarico R, Tran-Son-Tay R, Laquian L, Scali ST, Lee TC, Beck AW, Berceli SA, He Y. Haemodynamics of Different Configurations of a Left Subclavian Artery Stent Graft for Thoracic Endovascular Aortic Repair. Eur J Vasc Endovasc Surg 2019; 59:7-15. [PMID: 31761570 DOI: 10.1016/j.ejvs.2019.06.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/16/2019] [Accepted: 06/09/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Branched stent grafts represent a viable option for left subclavian artery (LSA) revascularisation in patients treated by thoracic endovascular aortic repair (TEVAR) for Zone 2 lesions. This study investigated the haemodynamic performance of different LSA branched stent graft configurations as potential determinants of thrombotic and stroke risks. METHODS A three dimensional aortic arch geometry extracted from post-operative computed tomography images of a TEVAR patient using a single LSA branched aortic endograft was modified in silico to obtain ten potential LSA branched stent graft configurations: five down facing (0-5 - 10 mm aortic protrusion with 10-12 mm internal diameter), four curved (30-60° with antegrade/retrograde orientation), and one LSA orifice misalignment. The 0 mm down facing stent graft was considered base configuration. Computational fluid dynamic analyses were performed to identify differences in pressure, energy, and wall shear stress (WSS) based parameters. RESULTS Total pressure drop and energy loss variations among configurations were not greater than 5 mmHg (6% of mean arterial pressure) and 5.7 mW (0.7% of cardiac power), respectively. Protrusions up to 5 mm created clinically insignificant flow disturbances. However, stent graft protrusions further into the aortic lumen created more complex haemodynamics, characterised by larger energy loss and more prominent flow recirculation. Protrusion greater than 5 mm into the lumen was associated with larger areas of elevated maximum WSS (>20 Pa) along the outer surface of the branched stent graft. CONCLUSION Arterial haemodynamic characteristics are affected by LSA branched stent graft configurations, with pressure drops and energy losses likely to be clinically insignificant. The length of the stent graft protrusion into the aortic lumen generated the largest haemodynamic variations in the aortic system. Protrusions up to 5 mm have smaller risk of potential thrombus generation. Conversely, larger protrusions into the aortic lumen showed more disturbed haemodynamics, suggesting a greater risk of potential thrombus formation, which may be clinically important over time.
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Affiliation(s)
- Rosamaria Tricarico
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Roger Tran-Son-Tay
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Liza Laquian
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA
| | - Salvatore T Scali
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA; North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - Teng-Chun Lee
- Division of Thoracic and Cardiovascular Surgery, University of Florida, Gainesville, FL, USA
| | - Adam W Beck
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA
| | - Scott A Berceli
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA; Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA; North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, FL, USA.
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27
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Stella S, Vergara C, Giovannacci L, Quarteroni A, Prouse G. Assessing the Disturbed Flow and the Transition to Turbulence in the Arteriovenous Fistula. J Biomech Eng 2019; 141:2730875. [PMID: 30968934 DOI: 10.1115/1.4043448] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Indexed: 11/08/2022]
Abstract
The arteriovenous fistula (AVF) is the main form of vascular access for hemodialysis patients, but its maintenance is very challenging. Its failure is mainly related to intimal hyperplasia (IH), leading to stenosis. The aim of this work was twofold: (i) to perform a computational study for the comparison of the disturbed blood dynamics in different configurations of AVF and (ii) to assess the amount of transition to turbulence developed by the specific geometric configuration of AVF. For this aim, we reconstructed realistic three-dimensional (3D) geometries of two patients with a side-to-end AVF, performing a parametric study by changing the angle of incidence at the anastomosis. We solved the incompressible Navier–Stokes equations modeling the blood as an incompressible and Newtonian fluid. Large eddy simulations (LES) were considered to capture the transition to turbulence developed at the anastomosis. The values of prescribed boundary conditions are obtained from clinical echo-color Doppler (ECD) measurements. To assess the disturbed flow, we considered hemodynamic quantities such as the velocity field, the pressure distribution, and wall shear stresses (WSS) derived quantities, whereas to quantify the transition to turbulence, we computed the standard deviation of the velocity field among different heartbeats and the turbulent kinetic energy.
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Affiliation(s)
- Simone Stella
- EOC-Ente Ospedaliero Cantonale, Lugano 6900, Switzerland; MOX, Dipartimento di Matematica, Politecnico di Milano, Milan 20133, Italy e-mail:
| | - Christian Vergara
- LABS, Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta,” Politecnico di Milano, Milan 20133, Italy e-mail:
| | - Luca Giovannacci
- EOC-Ente Ospedaliero Cantonale, Lugano 6900, Switzerland e-mail:
| | - Alfio Quarteroni
- MOX, Dipartimento di Matematica, Politecnico di Milano, Milan 20133, Italy e-mail:
| | - Giorgio Prouse
- EOC-Ente Ospedaliero Cantonale, Lugano 6900, Switzerland e-mail:
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28
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Tricarico R, He Y, Tran-Son-Tay R, Laquian L, Beck AW, Berceli SA. Anatomic and hemodynamic investigation of an occluded common carotid chimney stent graft for hybrid thoracic aortic aneurysm repair. JOURNAL OF VASCULAR SURGERY CASES INNOVATIONS AND TECHNIQUES 2019; 5:187-194. [PMID: 31193609 PMCID: PMC6536778 DOI: 10.1016/j.jvscit.2019.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/11/2019] [Indexed: 11/26/2022]
Abstract
We examined the possible reasons for common carotid artery chimney stent graft occlusion through computational fluid dynamics analyses of follow-up imaging of a patient-specific aortic configuration reconstructed from computed tomography aortography. Anatomic and hemodynamic parameters were extracted for the bilateral common carotid and subclavian arteries before and after endograft placement. Results suggested that postoperative reduction in lumen diameter within the chimney stent graft combined with an increased flow rate led to complex hemodynamics with high wall shear stress, probably resulting in high-shear thrombogenesis and chimney stent graft occlusion 2.6 years after the primary repair. Early postoperative duplex ultrasound imaging might help identify at-risk conditions.
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Affiliation(s)
- Rosamaria Tricarico
- Department of Biomedical Engineering, University of Florida, Gainesville, Fla
| | - Yong He
- North Florida/South Georgia Veterans Health System, Gainesville, Fla.,Department of Surgery, University of Florida, Gainesville, Fla
| | - Roger Tran-Son-Tay
- Department of Biomedical Engineering, University of Florida, Gainesville, Fla.,Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Fla
| | - Liza Laquian
- Department of Surgery, University of Florida, Gainesville, Fla
| | - Adam W Beck
- Division of Vascular Surgery and Endovascular Therapy, Department of Surgery, University of Alabama at Birmingham, Birmingham, Ala
| | - Scott A Berceli
- Department of Biomedical Engineering, University of Florida, Gainesville, Fla.,North Florida/South Georgia Veterans Health System, Gainesville, Fla.,Department of Surgery, University of Florida, Gainesville, Fla
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29
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Shiu YT, Rotmans JI, Geelhoed WJ, Pike DB, Lee T. Arteriovenous conduits for hemodialysis: how to better modulate the pathophysiological vascular response to optimize vascular access durability. Am J Physiol Renal Physiol 2019; 316:F794-F806. [PMID: 30785348 PMCID: PMC6580244 DOI: 10.1152/ajprenal.00440.2018] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 02/04/2019] [Accepted: 02/17/2019] [Indexed: 12/11/2022] Open
Abstract
Vascular access is the lifeline for patients on hemodialysis. Arteriovenous fistulas (AVFs) are the preferred vascular access, but AVF maturation failure remains a significant clinical problem. Currently, there are no effective therapies available to prevent or treat AVF maturation failure. AVF maturation failure frequently results from venous stenosis at the AVF anastomosis, which is secondary to poor outward vascular remodeling and excessive venous intimal hyperplasia that narrows the AVF lumen. Arteriovenous grafts (AVGs) are the next preferred vascular access when an AVF creation is not possible. AVG failure is primarily the result of venous stenosis at the vein-graft anastomosis, which originates from intimal hyperplasia development. Although there has been advancement in our knowledge of the pathophysiology of AVF maturation and AVG failure, this has not translated into effective therapies for these two important clinical problems. Further work will be required to dissect out the mechanisms of AVF maturation failure and AVG failure to develop more specific therapies. This review highlights the major recent advancements in AVF and AVG biology, reviews major clinical trials, and discusses new areas for future research.
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Affiliation(s)
- Yan-Ting Shiu
- Division of Nephrology, University of Utah , Salt Lake City, Utah
| | - Joris I Rotmans
- Department of Internal Medicine, Leiden University Medical Center , Leiden , The Netherlands
| | - Wouter Jan Geelhoed
- Department of Internal Medicine, Leiden University Medical Center , Leiden , The Netherlands
| | - Daniel B Pike
- Division of Nephrology, University of Utah , Salt Lake City, Utah
| | - Timmy Lee
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham , Birmingham, Alabama
- Veterans Affairs Medical Center , Birmingham, Alabama
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30
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Liu J, Tian L, Wang S, Luo Z. Study of Hepatic Vascular Dynamics Based on Symmetrical Pulsating Perfusion. Ann Transplant 2019; 24:214-222. [PMID: 31000689 PMCID: PMC6486798 DOI: 10.12659/aot.913008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Background The traditionally used perfusion method is constant flow. This study proposes a novel method called Symmetric Pulsating Flow (SPF) and verified that this method is applicable. Material/Methods The fluid dynamic behavior of perfusate in the vessel, the shear stress, and the vascular deformation were simulated based on the bi-directional fluid-structure interaction. The differences of the fluid dynamic behaviors and the mechanical characteristics of vascular wall were studied and compared between the 2 methods during the process of hepatic perfusion. The simulations and comparisons were carried out on 3 different vascular models. Results Utilizing the constant flow perfusion, a double vortex clearly appeared at the rear end of the foreign matter and reflux retention can be caused by the double vortex. The reflux retention caused lower shear stress against the vascular wall and thus brought new accumulation of foreign matter. The SPF perfusion, however, prevented the double vortex, and avoided such reflux retention during the vascular perfusion. In addition, the SPF can clean the vascular wall better with a slower speed, which causes less injury to the vessel, and the pulsating effect can reduce the accumulation of new foreign matter. Conclusions The SPF perfusion can clean the vascular wall more thoroughly with less injury.
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Affiliation(s)
- Jun Liu
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China (mainland)
| | - Lanlan Tian
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China (mainland)
| | - Songli Wang
- Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, National Demonstration Center for Experimental Mechanical and Electrical Engineering Education, Tianjin University of Technology, Tianjin, China (mainland)
| | - Zhiwei Luo
- Organization of Advanced Science and Technology, Kobe University, Kobe, Hyogo, Japan
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31
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Pike D, Shiu YT, Cho YF, Le H, Somarathna M, Isayeva T, Guo L, Symons JD, Kevil CG, Totenhagen J, Lee T. The effect of endothelial nitric oxide synthase on the hemodynamics and wall mechanics in murine arteriovenous fistulas. Sci Rep 2019; 9:4299. [PMID: 30862797 PMCID: PMC6414641 DOI: 10.1038/s41598-019-40683-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 02/19/2019] [Indexed: 11/12/2022] Open
Abstract
Creation of a hemodialysis arteriovenous fistula (AVF) causes aberrant vascular mechanics at and near the AVF anastomosis. When inadequately regulated, these aberrant mechanical factors may impede AVF lumen expansion to cause AVF maturation failure, a significant clinical problem with no effective treatments. The endothelial nitric oxide synthase (NOS3) system is crucial for vascular health and function, but its effect on AVF maturation has not been fully characterized. We hypothesize that NOS3 promotes AVF maturation by regulating local vascular mechanics following AVF creation. Here we report the first MRI-based fluid-structure interaction (FSI) study in a murine AVF model using three mouse strains: NOS3 overexpression (NOS3 OE) and knockout (NOS3−/−) on C57BL/6 background, with C57BL/6 as the wild-type control (NOS3+/+). When compared to NOS3+/+ and NOS3−/−, AVFs in the OE mice had larger lumen area. AVFs in the OE mice also had smoother blood flow streamlines, as well as lower blood shear stress at the wall, blood vorticity, inner wall circumferential stretch, and radial wall thinning at the anastomosis. Our results demonstrate that overexpression of NOS3 resulted in distinct hemodynamic and wall mechanical profiles associated with favorable AVF remodeling. Enhancing NOS3 expression may be a potential therapeutic approach for promoting AVF maturation.
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Affiliation(s)
- Daniel Pike
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.,Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Yan-Ting Shiu
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Yun-Fang Cho
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Ha Le
- Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Maheshika Somarathna
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tatyana Isayeva
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Lingling Guo
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - J David Symons
- Department of Nutrition and Integrative Physiology and Molecular Medicine Program, University of Utah, Salt Lake City, UT, USA.,Division of Endocrinology, Metabolism, and Diabetes, University of Utah, Salt Lake City, UT, USA
| | - Christopher G Kevil
- Departments of Pathology, Molecular and Cellular Physiology, and Cellular Biology and Anatomy, LSU Health Shreveport, Shreveport, LA, USA
| | - John Totenhagen
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timmy Lee
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL, USA. .,Veterans Affairs Medical Center, Birmingham, AL, USA.
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Aristokleous N, Houston JG, Browne LD, Broderick SP, Kokkalis E, Gandy SJ, Walsh MT. Morphological and hemodynamical alterations in brachial artery and cephalic vein. An image-based study for preoperative assessment for vascular access creation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e3136. [PMID: 30070048 DOI: 10.1002/cnm.3136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 06/04/2018] [Accepted: 07/15/2018] [Indexed: 06/08/2023]
Abstract
The current study aims to computationally evaluate the effect of right upper arm position on the geometric and hemodynamic characteristics of the brachial artery (BA) and cephalic vein (CV) and, furthermore, to present in detail the methodology to characterise morphological and hemodynamical healthy vessels. Ten healthy volunteers were analysed in two configurations, the supine (S) and the prone (P) position. Lumen 3D surface models were constructed from images acquired from a non-contrast MRI sequence. Then, the models were used to numerically compute the physiological range of geometric (n = 10) and hemodynamic (n = 3) parameters in the BA and CV. Geometric parameters such as curvature and tortuosity, and hemodynamic parameters based on wall shear stress (WSS) metrics were calculated with the use of computational fluid dynamics. Our results highlight that changes in arm position had a greater impact on WSS metrics of the BA by altering the mean and maximum blood flow rate of the vessel. Whereas, curvature and tortuosity were found not to be significantly different between positions. Inter-variability was associated with antegrade and retrograde flow in BA, and antegrade flow in CV. Shear stress was low and oscillatory shear forces were negligible. This data suggests that deviations from this state may contribute to the risk of accelerated intimal hyperplasia of the vein in arteriovenous fistulas. Therefore, preoperative conditions coupled with post-operative longitudinal data will aid the identification of such relationships.
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Affiliation(s)
- Nicolas Aristokleous
- Bio-Science and Bio-Engineering Research (BioSciBER), School of Engineering, Bernal Institute and the Health Research Institute, University of Limerick, Castletroy, Limerick, Ireland
| | - J Graeme Houston
- Department of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
- NHS Tayside Clinical Radiology, Ninewells Hospital, Dundee, UK
| | - Leonard D Browne
- Bio-Science and Bio-Engineering Research (BioSciBER), School of Engineering, Bernal Institute and the Health Research Institute, University of Limerick, Castletroy, Limerick, Ireland
| | - Stephen P Broderick
- Bio-Science and Bio-Engineering Research (BioSciBER), School of Engineering, Bernal Institute and the Health Research Institute, University of Limerick, Castletroy, Limerick, Ireland
| | - Efstratios Kokkalis
- Department of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | | | - Michael T Walsh
- Bio-Science and Bio-Engineering Research (BioSciBER), School of Engineering, Bernal Institute and the Health Research Institute, University of Limerick, Castletroy, Limerick, Ireland
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Boghosian ME, Hammes MS, Cassel KW, Akherat SMJ, Coe F. Restoration of wall shear stress in the cephalic vein during extreme hemodynamics. J Med Eng Technol 2018; 42:617-627. [PMID: 30942634 PMCID: PMC6714973 DOI: 10.1080/03091902.2019.1591534] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 02/13/2019] [Indexed: 02/02/2023]
Abstract
The surgical creation of an artery-vein connection via a Brachicephalic fistula (BCF) in patients with end stage renal disease (ESRD) provides a unique opportunity to study blood vessel response mechanisms to extreme hemodynamic conditions in relatively short timeframes. After BCF creation, the flow rate in the vein increases by an order of magnitude leading to separated flows and corresponding abnormally low, or negative, wall shear stress (WSS) in the curved arch segment of the cephalic vein. Locations of abnormally low WSS are shown to correlate with development of neointimal hyperplasia (NH) and subsequent stenosis. It is found that the stenosis, prior to a surgical intervention, restores the normal physiological WSS in the vein. As a result, this investigation provides evidence that the adaptation principle, known to apply in the arterial system, is also valid in the venous system. A novel graphical method is developed that combines clinical and computational data to assist in interpreting these physiological mechanisms including adaptation that lead to changes in vein geometry over time.
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Affiliation(s)
- M E Boghosian
- a Fluid Dynamic Research Center, Department of Mechanical , Materials, and Aerospace Engineering, Illinois Institute of Technology , Chicago , IL , USA
| | - M S Hammes
- b Section of Nephrology, Department of Medicine , University of Chicago , Chicago , IL , USA
| | - K W Cassel
- a Fluid Dynamic Research Center, Department of Mechanical , Materials, and Aerospace Engineering, Illinois Institute of Technology , Chicago , IL , USA
| | - S M J Akherat
- a Fluid Dynamic Research Center, Department of Mechanical , Materials, and Aerospace Engineering, Illinois Institute of Technology , Chicago , IL , USA
| | - F Coe
- b Section of Nephrology, Department of Medicine , University of Chicago , Chicago , IL , USA
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Non-contrast MRI methods as a tool for the pre-operative assessment and surveillance of the arterio-venous fistula for haemodialysis. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2018; 31:735-745. [DOI: 10.1007/s10334-018-0700-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 07/22/2018] [Accepted: 08/13/2018] [Indexed: 10/28/2022]
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Bozzetto M, Brambilla P, Rota S, Ene-Iordache B, Sironi S, Remuzzi G, Remuzzi A. Toward longitudinal studies of hemodynamically induced vessel wall remodeling. Int J Artif Organs 2018; 41:714-722. [PMID: 29998758 DOI: 10.1177/0391398818784207] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION: Autogenous arteriovenous fistula is the preferred vascular access for hemodialysis, but it has high rates of non-maturation and early failure due to vascular stenosis. Convincing evidence supports a key role of local hemodynamics in vascular remodeling, suggesting that unsteady and disturbed flow conditions may be related to stenosis formation in arteriovenous fistula. The purpose of our study was to explore the feasibility of coupling contrast-free magnetic resonance imaging and computational fluid dynamics in longitudinal studies to identify the role of local hemodynamic changes over time in inducing vessel wall remodeling in arteriovenous fistula. METHODS: We acquired contrast-free magnetic resonance imaging of arm vasculature at 1 week and 6 weeks after arteriovenous fistula creation in a 72-year-old patient. We then generated three-dimensional models and evaluated lumen cross-sectional area of arteriovenous fistula limbs. We performed high-resolution computational fluid dynamics to evaluate changes in local hemodynamics over time. RESULTS: Our contrast-free magnetic resonance imaging protocol provided good quality images in a short scan duration. We observed a homogeneous dilatation in the proximal artery, while there was a more pronounced lumen dilatation in the venous outflow as compared to a limited dilatation in the juxta-anastomotic vein. Furthermore, we observed a slight stabilization of the flow pattern over time, suggesting that vascular outward remodeling accommodates the flow to a more helicoidally phenotype. CONCLUSION: Coupling contrast-free magnetic resonance imaging and high-resolution computational fluid dynamics represents a promising approach to shed more light in the mechanisms of vascular remodeling and can be used for prospective clinical investigations aimed at identifying critical hemodynamic factors contributing to arteriovenous fistula failure.
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Affiliation(s)
- Michela Bozzetto
- 1 Department of Engineering and Applied Sciences, University of Bergamo, Dalmine, Italy
| | - Paolo Brambilla
- 2 USC Radiologia Diagnostica per Immagini 1, ASST Papa Giovanni XXIII-Universitá Milano-Bicocca, Bergamo, Italy
| | - Stefano Rota
- 3 Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Bogdan Ene-Iordache
- 4 Department of Biomedical Engineering, IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," Ranica, Italy
| | - Sandro Sironi
- 2 USC Radiologia Diagnostica per Immagini 1, ASST Papa Giovanni XXIII-Universitá Milano-Bicocca, Bergamo, Italy
| | - Giuseppe Remuzzi
- 3 Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy.,4 Department of Biomedical Engineering, IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," Ranica, Italy.,5 Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Andrea Remuzzi
- 6 Department of Management, Information and Production Engineering, University of Bergamo, Dalmine, Italy
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He Y, Shiu YT, Pike DB, Roy-Chaudhury P, Cheung AK, Berceli SA. Comparison of hemodialysis arteriovenous fistula blood flow rates measured by Doppler ultrasound and phase-contrast magnetic resonance imaging. J Vasc Surg 2018; 68:1848-1857.e2. [PMID: 29779960 DOI: 10.1016/j.jvs.2018.02.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 02/20/2018] [Indexed: 01/22/2023]
Abstract
OBJECTIVE The objective of this study was to compare blood flow rates measured by Doppler ultrasound (DUS) and phase-contrast magnetic resonance imaging (MRI) in patients having a hemodialysis arteriovenous fistula (AVF) and to identify scenarios in which there was significant discordance between these two approaches. METHODS Blood flow rates in the proximal artery (PA) and draining vein (DV) of newly created upper extremity AVFs were measured and compared using DUS and phase-contrast MRI at 1 day, 6 weeks, and 6 months postoperatively. RESULTS Blood flow rates in the PA measured by DUS (1155 ± 907 mL/min, mean ± standard deviation) and by MRI (1170 ± 657 mL/min) were not statistically different (P = .812) based on 78 data pairs from 49 patients. DV DUS flow (1277 ± 995 mL/min) and MRI flow (1130 ± 655 mL/min) were also not statistically different (P = .071) based on 64 data pairs. In both PA and DV, the two methods substantially agreed with each other (Cohen κ: PA, 0.66; DV, 0.67) when flow rates were put into four clinically relevant categories (<300, 300-599, 600-1499, and ≥1500 mL/min). The Bland-Altman analyses of DUS and MRI flow identified six and four outliers for PA and DV, respectively. Seven outliers had higher DUS than MRI flow, with all DUS scan sites having a large lumen or significant local curvature; the other three had lower DUS flow, partly due to an underestimation of lumen diameter by DUS. CONCLUSIONS DUS and MRI flow rates are generally comparable in both PA and DV. When DUS is used for flow measurements, careful attention to accurate lumen diameter measurements is needed and scan sites with marked curvature should be avoided. Our result may improve the accuracy of DUS-measured AVF blood flow rate.
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Affiliation(s)
- Yong He
- Department of Surgery, University of Florida, Gainesville, Fla; Malcom Randall VA Medical Center, Gainesville, Fla
| | - Yan-Ting Shiu
- Division of Nephrology & Hypertension, University of Utah, Salt Lake City, Utah
| | - Daniel B Pike
- Department of Bioengineering, University of Utah, Salt Lake City, Utah
| | | | - Alfred K Cheung
- Division of Nephrology & Hypertension, University of Utah, Salt Lake City, Utah; Medical Service, Veterans Affairs Salt Lake City Healthcare System, Salt Lake City, Utah; Department of Nephrology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China
| | - Scott A Berceli
- Department of Surgery, University of Florida, Gainesville, Fla; Malcom Randall VA Medical Center, Gainesville, Fla.
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Tricarico R, He Y, Laquian L, Scali ST, Tran-Son-Tay R, Beck AW, Berceli SA. Hemodynamic and Anatomic Predictors of Renovisceral Stent-Graft Occlusion Following Chimney Endovascular Repair of Juxtarenal Aortic Aneurysms. J Endovasc Ther 2017; 24:880-888. [PMID: 28914135 DOI: 10.1177/1526602817731096] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE To identify anatomic and hemodynamic changes associated with impending visceral chimney stent-graft occlusion after endovascular aneurysm repair (EVAR) with the chimney technique (chEVAR). METHODS A retrospective evaluation was performed of computed tomography scans from 41 patients who underwent juxtarenal chEVAR from 2008 to 2012 to identify stent-grafts demonstrating conformational changes following initial placement. Six subjects (mean age 74 years; 3 men) were selected for detailed reconstruction and computational hemodynamic analysis; 4 had at least 1 occluded chimney stent-graft. This subset of repairs was systematically analyzed to define the anatomic and hemodynamic impact of these changes and identify signature patterns associated with impending renovisceral stent-graft occlusion. Spatial and temporal analyses of cross-sectional area, centerline angle, intraluminal pressure, and wall shear stress (WSS) were performed within the superior mesenteric and renal artery chimney grafts used for repair. RESULTS Conformational changes in the chimney stent-grafts and associated perturbations, in both local WSS and pressure, were responsible for the 5 occlusions in the 13 stented branches. Anatomic and hemodynamic signatures leading to occlusion were identified within 1 month postoperatively, with a lumen area <14 mm2 (p=0.04), systolic pressure gradient >25 Pa/mm (p=0.03), and systolic WSS >45 Pa (p=0.03) associated with future chimney stent-graft occlusion. CONCLUSION Chimney stent-grafts at increased risk for occlusion demonstrated anatomic and hemodynamic signatures within 1 month of juxtarenal chEVAR. Analysis of these parameters in the early postoperative period may be useful for identifying and remediating these high-risk stent-grafts.
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Affiliation(s)
- Rosamaria Tricarico
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Yong He
- 2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Liza Laquian
- 3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Salvatore T Scali
- 2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Roger Tran-Son-Tay
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.,4 Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, USA
| | - Adam W Beck
- 5 University of Alabama School of Medicine, Birmingham, AL, USA
| | - Scott A Berceli
- 1 Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA.,2 North Florida/South Georgia Veterans Health System, University of Florida, Gainesville, FL, USA.,3 Department of Surgery, University of Florida, Gainesville, FL, USA
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Cunnane CV, Cunnane EM, Walsh MT. A Review of the Hemodynamic Factors Believed to Contribute to Vascular Access Dysfunction. Cardiovasc Eng Technol 2017; 8:280-294. [DOI: 10.1007/s13239-017-0307-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/09/2017] [Indexed: 11/29/2022]
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Pike D, Shiu YT, Somarathna M, Guo L, Isayeva T, Totenhagen J, Lee T. High resolution hemodynamic profiling of murine arteriovenous fistula using magnetic resonance imaging and computational fluid dynamics. Theor Biol Med Model 2017; 14:5. [PMID: 28320412 PMCID: PMC5360029 DOI: 10.1186/s12976-017-0053-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/14/2017] [Indexed: 11/21/2022] Open
Abstract
Background Arteriovenous fistula (AVF) maturation failure remains a major cause of morbidity and mortality in hemodialysis patients. The two major etiologies of AVF maturation failure are early neointimal hyperplasia development and persistent inadequate outward remodeling. Although hemodynamic changes following AVF creation may impact AVF remodeling and contribute to neointimal hyperplasia development and impaired outward remodeling, detailed AVF hemodynamics are not yet fully known. Since murine AVF models are valuable tools for investigating the pathophysiology of AVF maturation failure, there is a need for a new approach that allows the hemodynamic characterization of murine AVF at high resolutions. Methods This methods paper presents a magnetic resonance imaging (MRI)-based computational fluid dynamic (CFD) method that we developed to rigorously quantify the evolving hemodynamic environment in murine AVF. The lumen geometry of the entire murine AVF was reconstructed from high resolution, non-contrast 2D T2-weighted fast spin echo MRI sequence, and the flow rates of the AVF inflow and outflow were extracted from a gradient echo velocity mapping sequence. Using these MRI-obtained lumen geometry and inflow information, CFD modeling was performed and used to calculate blood flow velocity and hemodynamic factors at high resolutions (on the order of 0.5 μm spatially and 0.1 ms temporally) throughout the entire AVF lumen. We investigated both the wall properties (including wall shear stress (WSS), wall shear stress spatial gradient, and oscillatory shear index (OSI)) and the volumetric properties (including vorticity, helicity, and Q-criterion). Results Our results demonstrate increases in AVF flow velocity, WSS, spatial WSS gradient, and OSI within 3 weeks post-AVF creation when compared to pre-surgery. We also observed post-operative increases in flow disturbances and vortices, as indicated by increased vorticity, helicity, and Q-criterion. Conclusions This novel protocol will enable us to undertake future mechanistic studies to delineate the relationship between hemodynamics and AVF development and characterize biological mechanisms that regulate local hemodynamic factors in transgenic murine AVF models. Electronic supplementary material The online version of this article (doi:10.1186/s12976-017-0053-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel Pike
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.,Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Yan-Ting Shiu
- Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.,Division of Nephrology and Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Maheshika Somarathna
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, 1720 2nd Ave South, Birmingham, AL, 35294-0007, USA
| | - Lingling Guo
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, 1720 2nd Ave South, Birmingham, AL, 35294-0007, USA
| | - Tatyana Isayeva
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, 1720 2nd Ave South, Birmingham, AL, 35294-0007, USA
| | - John Totenhagen
- Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timmy Lee
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, 1720 2nd Ave South, Birmingham, AL, 35294-0007, USA. .,Veterans Affairs Medical Center, Birmingham, AL, USA.
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Abstract
Autologous arteriovenous fistula (AVF) is the preferred choice for providing vascular access to hemodialysis (HD) patients, but it is still affected by high incidence of non-maturation or early failure. After creation, AVF must undergo vascular remodeling, a process characterized by an increase in blood vessel diameter and wall thickness, to allow efficient and adequate HD. A growing body of evidence indicates that AVF maturation is related to the response of endothelial cells (ECs) to changes in wall shear stress (WSS), and in particular, to changes of its peak value. The reasons why important number of AVFs are affected by non-maturation or early failure still remain to be elucidated, but it has been suggested that local hemodynamic conditions with highly disturbed flow patterns may play an important role. In the present contribution, we addressed the role of WSS on AVF maturation, clarifying mechanisms that affect the clinical outcome of AVF creation. We also pointed out the need of non-invasive longitudinal studies, with repeated observations of hemodynamic parameters and structural changes during time, to obtain evidence of a cause-and-effect relationship between the presence of disturbed flow and AVF maturation failure. This understanding may be fundamental in the future to ameliorate clinical outcome of AVF creation, with a great impact on the clinical management of HD patients and their quality of life.
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GRUS T, LAMBERT L, MATĚCHA J, GRUSOVÁ G, ŠPAČEK M, MLČEK M. The Ratio of Diameters Between the Target Artery and the Bypass Modifies Hemodynamic Parameters Related to Intimal Hyperplasia in the Distal End-to-Side Anastomosis. Physiol Res 2016; 65:901-908. [DOI: 10.33549/physiolres.933297] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Hemodynamics in the distal end-to-side anastomosis is related to early development of intimal hyperplasia and bypass failure. In this study we investigated the effect of diameter ratios between the target artery and the bypass at three different angles of the connection. The pulsatile flow field was visualized using particle image velocimetry in transparent models with three different angles of the connection (25°, 45°, 60°) and the diameter ratio between the bypass and the target artery was 4.6 mm : 6 mm, 6 mm : 6 mm, and 7.5 mm : 6 mm. Six parameters including location and oscillation of the stagnation point, local energy dissipation, wall shear stress (WSS), oscillatory shear index, spatial and temporal gradient of WSS and their distribution in the target artery were calculated from the flow field. In the wider bypass, the stagnation point oscillated in a greater range and was located more proximal to the anastomosis. Energy dissipation was minimal in a wider bypass with a more acute angle. The maximum WSS values were tree times greater in a narrow bypass and concentrated in a smaller circular region at the floor of the anastomosis. The oscillatory shear index increased with wider bypass and more acute angle. The maximum of spatial gradient of WSS concentrated around the floor and toe of the anastomosis and decreased with more acute angle and wider bypass, the temporal gradient of WSS was stretched more towards the side wall. Greater bypass to target vessel ratio and more acute anastomosis angle promote hemodynamics known to reduce formation of intimal hyperplasia.
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Affiliation(s)
| | - L. LAMBERT
- Department of Radiology, First Faculty of Medicine, Charles University in Prague, Czech Republic
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Assessing radiocephalic wrist arteriovenous fistulas of obtuse anastomosis using computational fluid dynamics and clinical application. J Vasc Access 2016; 17:512-520. [PMID: 27791257 DOI: 10.5301/jva.5000607] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2016] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION A radiocephalic arteriovenous fistula (AVF) is the best choice for achieving vascular access (VA) for hemodialysis, but this AVF has high rates of early failure due to juxta-anastomotic stenosis, making it impossible to use for dialysis. Low hemodynamic shear stress contributes to the pathophysiology of VA failure due to secondary thrombosis, stenosis, and re-occlusion after percutaneous intervention. METHODS We used a computational fluid dynamics (CFDs) approach to evaluate the shear stress distribution and minimize its effects under various conditions including changes in the anastomosis angle. A three-dimensional computational domain was designed for arteriovenous end-to-side anastomosis based on anastomosis angles of 45°, 90° and including 135° angle of an obtuse anastomosis using three-dimensional design software. COMSOL Multiphysics® simulation software was used to identify the hemodynamic factors influencing wall shear stress at the anastomosis site using a low Reynolds number k-ε turbulence model that included non-Newtonian blood flow characteristics, the complete cardiac pulse cycle, and distention of blood vessels. In preliminary clinical study, all 201 patients who received a radiocephalic wrist AVF from January 2009 to February 2014 were divided into classic and obtuse angle groups. RESULTS The CFD results showed that the largest anastomosis angle (135°) resulted in lower shear stress, which would help reduce AVF failures. This obtuse angle was preferred, as it minimized the development of anastomotic stenosis and tended to favor primary and primary-assisted patency in clinical study. CONCLUSIONS An obtuse radiocephalic wrist AVF shows more favorable patency compared to a classic radiocephalic AVF. Surgeons establishing a radiocephalic wrist AVF would be better to consider an AVF with an obtuse anastomosis.
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Lee T, Misra S. New Insights into Dialysis Vascular Access: Molecular Targets in Arteriovenous Fistula and Arteriovenous Graft Failure and Their Potential to Improve Vascular Access Outcomes. Clin J Am Soc Nephrol 2016; 11:1504-1512. [PMID: 27401527 PMCID: PMC4974876 DOI: 10.2215/cjn.02030216] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Vascular access dysfunction remains a major cause of morbidity and mortality in hemodialysis patients. At present there are few effective therapies for this clinical problem. The poor understanding of the pathobiology that leads to arteriovenous fistula (AVF) and graft (AVG) dysfunction remains a critical barrier to development of novel and effective therapies. However, in recent years we have made substantial progress in our understanding of the mechanisms of vascular access dysfunction. This article presents recent advances and new insights into the pathobiology of AVF and AVG dysfunction and highlights potential therapeutic targets to improve vascular access outcomes.
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Affiliation(s)
- Timmy Lee
- Department of Medicine and Division of Nephrology, University of Alabama at Birmingham, Birmingham, Alabama
- Veterans Affairs Medical Center, Birmingham, Alabama; and
| | - Sanjay Misra
- Vascular and Interventional Radiology Translational Laboratory, Department of Radiology, Mayo Clinic, Rochester, Minnesota
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Browne LD, Bashar K, Griffin P, Kavanagh EG, Walsh SR, Walsh MT. The Role of Shear Stress in Arteriovenous Fistula Maturation and Failure: A Systematic Review. PLoS One 2015; 10:e0145795. [PMID: 26716840 PMCID: PMC4696682 DOI: 10.1371/journal.pone.0145795] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 12/08/2015] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs). Although the exact mechanisms triggering failure remain unclear, abnormal hemodynamic profiles are thought to mediate vascular remodelling and can adversely impact on fistula patency. AIM The review aims to clarify the role of shear stress on outward remodelling during maturation and evaluate the evidence supporting theories related to the localisation and development of intimal hyperplasia within AVFs. METHODS A systematic review of studies comparing remodelling data with hemodynamic data obtained from computational fluid dynamics of AVFs during and after maturation was conducted. RESULTS Outward remodelling occurred to reduce or normalise the level of shear stress over time in fistulae with a large radius of curvature (curved) whereas shear stress was found to augment over time in fistulae with a small radius of curvature (straight) coinciding with minimal to no increases in lumen area. Although this review highlighted that there is a growing body of evidence suggesting low and oscillating shear stress may stimulate the initiation and development of intimal medial thickening within AVFs. Further lines of evidence are needed to support the disturbed flow theory and outward remodelling findings before surgical configurations and treatment strategies are optimised to conform to them. This review highlighted that variation between the time of analysis, classification of IH, resolution of simulations, data processing techniques and omission of various shear stress metrics prevented forming pooling of data amongst studies. CONCLUSION Standardised measurements and data processing techniques are needed to comprehensively evaluate the relationship between shear stress and intimal medial thickening. Advances in image acquisition and flow quantifications coupled with the increasing prevalence of longitudinal studies commencing from fistula creation offer viable techniques and strategies to robustly evaluate the relationship between shear stress and remodelling during maturation and thereafter.
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Affiliation(s)
- Leonard D. Browne
- Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, The Health Research Institute, University of Limerick, Limerick, Ireland
| | - Khalid Bashar
- Department of Vascular Surgery, Limerick University Hospital, Dooradoyle, Limerick, Ireland
| | - Philip Griffin
- Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, The Health Research Institute, University of Limerick, Limerick, Ireland
| | - Eamon G. Kavanagh
- Department of Vascular Surgery, Limerick University Hospital, Dooradoyle, Limerick, Ireland
| | - Stewart R. Walsh
- Department of Vascular Surgery, Limerick University Hospital, Dooradoyle, Limerick, Ireland
- Department of Surgery, National University of Ireland, Galway, Ireland
| | - Michael T. Walsh
- Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, The Health Research Institute, University of Limerick, Limerick, Ireland
- * E-mail:
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45
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Bozzetto M, Ene-Iordache B, Remuzzi A. Transitional Flow in the Venous Side of Patient-Specific Arteriovenous Fistulae for Hemodialysis. Ann Biomed Eng 2015; 44:2388-2401. [PMID: 26698581 DOI: 10.1007/s10439-015-1525-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 11/29/2015] [Indexed: 01/28/2023]
Abstract
Arteriovenous fistula (AVF) is the first choice for providing vascular access for hemodialysis patients, but maintaining its patency is challenging. AVF failure is primarily due to development of neointimal hyperplasia (NH) and subsequent stenosis. Using idealized models of AVF we previously suggested that reciprocating hemodynamic wall shear is implicated in vessel stenosis. The aim of the present study was to investigate local hemodynamics in patient-specific side-to-end AVF. We reconstructed realistic geometrical models of four AVFs from magnetic resonance images acquired in a previous clinical study. High-resolution computational fluid dynamics simulations using patient-specific blood rheology and flow boundary conditions were performed. We then characterized the flow field and categorized disturbed flow areas by means of established hemodynamic wall parameters. In all AVF, either in upper or lower arm location, we consistently observed transitional laminar to turbulent-like flow developing in the juxta-anastomotic vein and damping towards the venous outflow, but not in the proximal artery. High-frequency fluctuations of the velocity vectors in these areas result in eddies that induce similar oscillations of wall shear stress vector. This condition may importantly impair the physiological response of endothelial cells to blood flow and be responsible for NH formation in newly created AVF.
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Affiliation(s)
- Michela Bozzetto
- Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi, 3, 24020, Ranica, BG, Italy
| | - Bogdan Ene-Iordache
- Department of Biomedical Engineering, IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Via G.B. Camozzi, 3, 24020, Ranica, BG, Italy
| | - Andrea Remuzzi
- Department of Biomedical Engineering, 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, Viale Marconi, 5, Dalmine, 24044, BG, Italy.
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46
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Broderick SP, Houston JG, Walsh MT. The influence of the instabilities in modelling arteriovenous junction haemodynamics. J Biomech 2015; 48:3591-8. [DOI: 10.1016/j.jbiomech.2015.07.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/29/2015] [Accepted: 07/30/2015] [Indexed: 10/23/2022]
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Assessment of Novel Anti-thrombotic Fusion Proteins for Inhibition of Stenosis in a Porcine Model of Arteriovenous Graft. PLoS One 2015; 10:e0137381. [PMID: 26360605 PMCID: PMC4567316 DOI: 10.1371/journal.pone.0137381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/16/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Hemodialysis arteriovenous synthetic grafts (AVG) provide high volumetric blood flow rates shortly after surgical placement. However, stenosis often develops at the vein-graft anastomosis contributing to thrombosis and early graft failure. Two novel fusion proteins, ANV-6L15 and TAP-ANV, inhibit the tissue factor/factor VIIa coagulation complex and the factor Xa/factor Va complex, respectively. Each inhibitor domain is fused to an annexin V domain that targets the inhibitor activity to sites of vascular injury to locally inhibit thrombosis. This study's objective was to determine if these antithrombotic proteins are safe and effective in inhibiting AVG stenosis. METHODS A bolus of either TAP-ANV or ANV-6L15 fusion protein was administered intravenously immediately prior to surgical placement of a synthetic graft between the external jugular vein and common carotid artery in a porcine model. At surgery, the vein and artery were irrigated with the anti-thrombotic fusion protein. Control animals received intravenous heparin. At 4 weeks, MRI was performed to evaluate graft patency, the pigs were then euthanized and grafts and attached vessels were explanted for histomorphometric assessment of neointimal hyperplasia at the vein-graft anastomosis. Blood was collected at surgery, immediately after surgery and at euthanasia for serum metabolic panels and coagulation chemistries. RESULTS No acute thrombosis occurred in the control group or in either experimental group. No abnormal serum chemistries, activated clotting times or PT, PTT values were observed after treatment in experimental or control animals. However, at the vein-graft anastomosis, there was no difference between the control and experimental groups in cross-sectional lumen areas, as measured on MRI, and no difference in hyperplasia areas as determined by histomorphometry. These results suggest that local irrigation of TAP-ANV or ANV-6L15 intra-operatively was as effective in inhibiting acute graft thrombosis as intravenous administration of heparin, but failed to inhibit hyperplasia development and stenosis in AVG.
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48
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Rehfuss J, Scali S, He Y, Schmit B, Desart K, Nelson P, Berceli S. The correlation between computed tomography and duplex evaluation of autogenous vein bypass grafts and their relationship to failure. J Vasc Surg 2015; 62:1546-54.e1. [PMID: 26365660 DOI: 10.1016/j.jvs.2015.06.220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/24/2015] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Duplex ultrasound (DUS) imaging for vein bypass graft (VBG) surveillance is confounded by technical and physiologic factors that reduce the sensitivity for detecting impending graft failure. In contrast, three-dimensional computed tomography angiography (CTA) offers high-fidelity anatomic characterization of VBGs, but its utility in detecting at risk grafts is unknown. The current study analyzed the correlation between DUS and CTA for detection of vein graft stenosis and evaluated the relationship of the observed abnormalities to VBG failure. METHODS Consecutive lower extremity VBG patients underwent surveillance with concurrent DUS imaging and CTA at 1 week and at 1, 6, and 12 months postoperatively. A standardized algorithm was used for CT reconstruction and extraction of the lumen geometries at 1-mm intervals. At each interval, CT-derived cross-sectional areas were coregistered and correlated to DUS peak systolic velocities (PSVs) within six predesignated anatomic zones and then analyzed for outcome association. Vein graft failure was defined as pathologic change within a given anatomic zone resulting in thrombosis, amputation, or reintervention within the 6-month period after the observed time point. RESULTS The study recruited 54 patients, and 10 (18%) experienced failure ≤18 months of implantation. The expected inverse relationship between cross-sectional area and PSV was only weakly correlated (Spearman rank coefficient = -0.19). Moderate elevations in the PSV ratio (PSVr; 2-3.5) were frequently transient, with 14 of 18 grafts (78%) demonstrating ratio reduction on subsequent imaging. A PSVr ≥3.5 was associated with a 67% failure rate. CT stenosis <50% was highly correlated with success (0 failures); however, high-grade (>80%) CT stenosis was more likely to succeed than to fail (25%). Significant discordance between CT and DUS was found in 18 patients. Although 14 of these patients had CT stenosis >70% with a PSVr <3.5, subsequent failure occurred in only two. Conversely, graft failure occurred in three of four patients with CT stenosis <70% but PSVr >3.5. Focused analysis of these patients using computational fluid dynamic modeling demonstrated that vein side branches, local tortuosity, regional diameter variations, and venovenostomies were the drivers of these discrepancies. CONCLUSIONS This analysis demonstrated that a PSVr ≥3.5 is strongly correlated with VBG failure, whereas the natural history of moderately elevated PSVr (2-3.5) is largely clinically benign. Although minimum stenosis on the CT scan was highly predictive of success, high-grade CT stenosis was infrequently associated with failure. The interaction of anatomic features with the local flow dynamics was identified as the primary confounder for a direct correlation between CT and DUS imaging.
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Affiliation(s)
- Jonathan Rehfuss
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Salvatore Scali
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla.
| | - Yong He
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Bradley Schmit
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Kenneth Desart
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
| | - Peter Nelson
- Division of Vascular Surgery, University of South Florida, Tampa, Fla
| | - Scott Berceli
- Division of Vascular Surgery and Endovascular Therapy, University of Florida, Gainesville, Fla
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49
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Disturbed flow in a patient-specific arteriovenous fistula for hemodialysis: Multidirectional and reciprocating near-wall flow patterns. J Biomech 2015; 48:2195-200. [DOI: 10.1016/j.jbiomech.2015.04.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 03/27/2015] [Accepted: 04/05/2015] [Indexed: 11/18/2022]
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50
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Yamamoto K, Protack CD, Kuwahara G, Tsuneki M, Hashimoto T, Hall MR, Assi R, Brownson KE, Foster TR, Bai H, Wang M, Madri JA, Dardik A. Disturbed shear stress reduces Klf2 expression in arterial-venous fistulae in vivo. Physiol Rep 2015; 3:3/3/e12348. [PMID: 25780089 PMCID: PMC4393175 DOI: 10.14814/phy2.12348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Laminar shear stress (SS) induces an antiproliferative and anti-inflammatory endothelial phenotype and increases Klf2 expression. We altered the diameter of an arteriovenous fistula (AVF) in the mouse model to determine whether increased fistula diameter produces disturbed SS in vivo and if acutely increased disturbed SS results in decreased Klf2 expression. The mouse aortocaval fistula model was performed with 22, 25, or 28 gauge needles to puncture the aorta and the inferior vena cava. Duplex ultrasound was used to examine the AVF and its arterial inflow and venous outflow, and SS was calculated. Arterial samples were examined with western blot, immunohistochemistry, and immunofluorescence analysis for proteins and qPCR for RNA. Mice with larger diameter fistulae had diminished survival but increased AVF patency. Increased SS magnitudes and range of frequencies were directly proportional to the needle diameter in the arterial limb proximal to the fistula but not in the venous limb distal to the fistula, with 22-gauge needles producing the most disturbed SS in vivo. Klf2 mRNA and protein expression was diminished in the artery proximal to the fistula in proportion to increasing SS. Increased fistula diameter produces increased SS magnitude and frequency, consistent with disturbed SS in vivo. Disturbed SS is associated with decreased mRNA and protein expression of Klf2. Disturbed SS and reduced Klf2 expression near the fistula are potential therapeutic targets to improve AVF maturation.
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Affiliation(s)
- Kota Yamamoto
- Veterans Affairs Connecticut Healthcare Systems, West Haven, Connecticut Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Clinton D Protack
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Go Kuwahara
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Masayuki Tsuneki
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Pathology, Yale University School of Medicine, New Haven, Connecticut Division of Cancer Biology, National Cancer Center Research Institute, Tokyo, Japan
| | - Takuya Hashimoto
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Michael R Hall
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Roland Assi
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Kirstyn E Brownson
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Trenton R Foster
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Hualong Bai
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Mo Wang
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
| | - Joseph A Madri
- Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Pathology, Yale University School of Medicine, New Haven, Connecticut
| | - Alan Dardik
- Veterans Affairs Connecticut Healthcare Systems, West Haven, Connecticut Vascular Biology & Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut Department of Surgery, Yale University School of Medicine, New Haven, Connecticut
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