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Wang F, Wang B, Guo J, Zhang T, Mu W, Liu C. Computational model-based hemodynamic comparisons of traditional and modified idealized models of autologous radiocephalic fistula. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2024:e3856. [PMID: 39075745 DOI: 10.1002/cnm.3856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 06/30/2024] [Accepted: 07/12/2024] [Indexed: 07/31/2024]
Abstract
Autologous arteriovenous fistula (AVF) is a commonly used vascular access (VA) for hemodialysis, and hemodynamic changes are one of the main factors for its failure. To explore the effect of geometry on the hemodynamics in the AVF, a modified model is built with a gradual and smooth turn at the anastomosis and is compared with the traditional model, which has an abrupt sharp turn at the anastomisis. Transient computational fluid dynamics (CFD) simulations were performed for the comparison and analysis of the hemodynamic fields of the two models at different stages of the pulse cycle. The results showed that the low shear stress region and high oscillatory shear stress region in the modified AVF model coincided with regions of intimal hyperplasia that have been identified by previous studies. A comparison with the blood flow velocities measured in vivo was performed, and the error between the simulation results and the medical data was reduced by 22% in the modified model, which verifies the rationality and utility of the modified model.
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Affiliation(s)
- Fan Wang
- School of Quality and Technical Supervision, Hebei University, Baoding, Hebei, China
| | - Baohui Wang
- School of Quality and Technical Supervision, Hebei University, Baoding, Hebei, China
| | - Jinfeng Guo
- School of Quality and Technical Supervision, Hebei University, Baoding, Hebei, China
| | - Tian Zhang
- School of Quality and Technical Supervision, Hebei University, Baoding, Hebei, China
| | - Weina Mu
- School of Quality and Technical Supervision, Hebei University, Baoding, Hebei, China
- Ultrasonography Department, Baoding No.1 Central Hospital, Baoding, Hebei, China
| | - Chunhui Liu
- Affiliated Hospital of Hebei University/School of Clinical Medicine, Hebei University, Baoding, Hebei, China
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Marcinnò F, Vergara C, Giovannacci L, Quarteroni A, Prouse G. Computational fluid-structure interaction analysis of the end-to-side radio-cephalic arteriovenous fistula. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 249:108146. [PMID: 38593514 DOI: 10.1016/j.cmpb.2024.108146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 01/15/2024] [Accepted: 03/24/2024] [Indexed: 04/11/2024]
Abstract
BACKGROUND AND OBJECTIVE In the current work, we present a descriptive fluid-structure interaction computational study of the end-to-side radio-cephalic arteriovenous fistula. This allows us to account for the different thicknesses and elastic properties of the radial artery and cephalic vein. METHODS The core of the work consists in simulating different arteriovenous fistula configurations obtained by virtually varying the anastomosis angle, i.e. the angle between the end of the cephalic vein and the side of the radial artery. Since the aim of the work is to understand the blood dynamics in the very first days after the surgical intervention, the radial artery is considered stiffer and thicker than the cephalic vein. RESULTS Our results demonstrate that both the diameter of the cephalic vein and the anastomosis angle play a crucial role to obtain a blood dynamics without re-circulation regions that could prevent fistula failure. CONCLUSIONS When an anastomosis angle close to the perpendicular direction with respect to the radial artery is combined with a large diameter of the cephalic vein, the recirculation regions and the low Wall Shear Stress (WSS) zones are reduced. Conversely, from a structural point of view, a low anastomosis angle with a large diameter of the cephalic vein reduces the mechanical stress acting on the vessel walls.
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Affiliation(s)
- Fabio Marcinnò
- Institute of Mathematics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Christian Vergara
- LaBS, Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Milan, Italy.
| | - Luca Giovannacci
- Centro Vascolare Ticino, EOC-Ente Ospedaliero Cantonale, Ticino, Switzerland.
| | - Alfio Quarteroni
- Institute of Mathematics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; MOX, Dipartimento di Matematica, Politecnico di Milano, Milan, Italy.
| | - Giorgio Prouse
- Centro Vascolare Ticino, EOC-Ente Ospedaliero Cantonale, Ticino, Switzerland.
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La Marca MA, Dinoto E, Rodriquenz E, Pecoraro F, Turchino D, Mirabella D. Brachial artery aneurysm after hemodialysis fistula ligation: Case reports and review of literature. Int J Surg Case Rep 2024; 115:109306. [PMID: 38280341 PMCID: PMC10839962 DOI: 10.1016/j.ijscr.2024.109306] [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: 10/05/2023] [Revised: 01/20/2024] [Accepted: 01/23/2024] [Indexed: 01/29/2024] Open
Abstract
INTRODUCTION Brachial artery aneurysm (BAA) following long-standing arteriovenous fistula (AVF) ligation after renal transplantation is odd. CASE PRESENTATION Two cases of brachial artery aneurysm treated with bypass (a saphenous vein graft and a PTFE graft). In the first patient no complications were recorded whereas an infection was diagnosed after 6 months from the procedure in the second treatment. CLINICAL DISCUSSION Multiple factors activated by stress on the vessel wall followed by fistula ligation are the cause of vascular remodeling of the three layers making up the wall with possible evolution in aneurysmatic lesions. In literature the gold standard for this lesion is the surgical approach, only one endovascular procedure is reported. The traditional surgical approach uses the autologous vein or prosthetic PTFE grafts. CONCLUSION Brachial artery aneurysm is a complication that affects patients undergoing renal transplantation who have already undergone AVF ligation. In our experience autologous vein graft represented the best solution.
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Affiliation(s)
- M A La Marca
- Vascular Surgery Unit - AOUP Policlinico 'P. Giaccone', Palermo, Italy
| | - E Dinoto
- Vascular Surgery Unit - AOUP Policlinico 'P. Giaccone', Palermo, Italy.
| | - E Rodriquenz
- Vascular Surgery Unit - AOUP Policlinico 'P. Giaccone', Palermo, Italy
| | - F Pecoraro
- Vascular Surgery Unit - AOUP Policlinico 'P. Giaccone', Palermo, Italy; Department of Surgical, Oncological and Oral Sciences - University of Palermo, Italy
| | - D Turchino
- Department of Public Health, Vascular Surgery Unit, University Federico II of Naples, Italy
| | - D Mirabella
- Vascular Surgery Unit - AOUP Policlinico 'P. Giaccone', Palermo, Italy
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Cunnane CV, Houston JG, Moran DT, Broderick SP, Ross RA, Walsh MT. Spiral Laminar Flow is Associated with a Reduction in Disturbed Shear in Patient-Specific Models of an Arteriovenous Fistula. Cardiovasc Eng Technol 2023; 14:152-165. [PMID: 36151366 DOI: 10.1007/s13239-022-00644-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/03/2022] [Indexed: 11/02/2022]
Abstract
PURPOSE Areas of disturbed shear that arise following arteriovenous fistula (AVF) creation are believed to contribute to the development of intimal hyperplasia (IH). The presence of helical flow can suppress areas of disturbed shear, which may protect the vasculature from IH. Therefore, the aim of this study is to determine if helical flow, specifically spiral laminar flow (SLF), is present in patient-specific AVF models and is associated with a reduction in exposure to disturbed shear. METHODS Four AVF were imaged using MRI within the first two weeks following fistula creation. Patient-specific boundary conditions were obtained using phase-contrast MRI and applied at the inlet and outlets of each model. Computational fluid dynamics was used to analyse the hemodynamics in each model and compare the helical content of the flow to the distribution of disturbed shear. RESULTS BC-1 and RC-2 are characterised by the presence of SLF, which coincides with the lowest distribution of disturbed shear. Contrastingly, SLF is absent from BC-2 and RC-1 and experience the largest amount of disturbed shear. Interestingly, BC-2 and RC-1 developed an anastomosis stenosis, while BC-1 and RC-2 remained stenosis free. CONCLUSION These findings are in agreement with previous clinical studies and further highlight the clinical potential of SLF as a prognostic marker for a healthy AVF, as its presence correlates with an overall reduction in exposure to disturbed shear and a decrease in the incidence of AVF dysfunction, albeit in a small sample size.
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Affiliation(s)
- Connor V Cunnane
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - J Graeme Houston
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Daniel T Moran
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - Stephen P Broderick
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland
| | - Rose A Ross
- NHS Tayside Vascular Department, Ninewells Hospital, Dundee, UK
| | - Michael T Walsh
- Biomaterials Cluster, Bernal Institute, University of Limerick, Limerick, Ireland.
- School of Engineering, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
- Health Research Institute, University of Limerick, Limerick, Ireland.
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5
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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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Szabo B, Gasz B, Fazekas LA, Varga A, Kiss-Papai L, Matolay O, Rezsabek Z, Al-Smadi MW, Nemeth N. Heterogeneous Maturation of Arterio-Venous Fistulas and Loop-Shaped Venous Interposition Grafts: A Histological and 3D Flow Simulation Comparison. Biomedicines 2022; 10:biomedicines10071508. [PMID: 35884813 PMCID: PMC9313372 DOI: 10.3390/biomedicines10071508] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/13/2022] [Accepted: 06/24/2022] [Indexed: 11/29/2022] Open
Abstract
Vascular graft maturation is associated with blood flow characteristics, such as velocity, pressure, vorticity, and wall shear stress (WSS). Many studies examined these factors separately. We aimed to examine the remodeling of arterio-venous fistulas (AVFs) and loop-shaped venous interposition grafts, together with 3D flow simulation. Thirty male Wistar rats were randomly and equally divided into sham-operated, AVF, and loop-shaped venous graft (Loop) groups, using the femoral and superficial inferior epigastric vessels for anastomoses. Five weeks after surgery, the vessels were removed for histological evaluation, or plastic castings were made and scanned for 3D flow simulation. Remodeling of AVF and looped grafts was complete in 5 weeks. Histology showed heterogeneous morphology depending on the distribution of intraluminal pressure and WSS. In the Loop group, an asymmetrical WSS distribution coincided with the intima hyperplasia spots. The tunica media was enlarged only when both pressure and WSS were high. The 3D flow simulation correlated with the histological findings, identifying “hotspots” for intimal hyperplasia formation, suggesting a predictive value. These observations can be useful for microvascular research and for quality control in microsurgical training.
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Affiliation(s)
- Balazs Szabo
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
| | - Balazs Gasz
- Department of Surgical Research and Techniques, Faculty of Medicine, University of Pecs, Szigeti u. 12, H-7624 Pecs, Hungary; (B.G.); (L.K.-P.)
| | - Laszlo Adam Fazekas
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
| | - Adam Varga
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
| | - Levente Kiss-Papai
- Department of Surgical Research and Techniques, Faculty of Medicine, University of Pecs, Szigeti u. 12, H-7624 Pecs, Hungary; (B.G.); (L.K.-P.)
| | - Orsolya Matolay
- Department of Pathology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary;
| | - Zsofia Rezsabek
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
| | - Mohammad W. Al-Smadi
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
| | - Norbert Nemeth
- Department of Operative Techniques and Surgical Research, Faculty of Medicine, University of Debrecen, Moricz Zsigmond u. 22, H-4032 Debrecen, Hungary; (B.S.); (L.A.F.); (A.V.); (Z.R.); (M.W.A.-S.)
- Correspondence: ; Tel./Fax: +36-52-416-915
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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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Barac S, Rata AL, Popescu AI, Onofrei RR, Chiriac SD. True Brachial Artery Aneurysm in Patients with Previous Arterio-Venous Fistula Ligation and Immunosuppressant Therapy for Renal Transplantation: Case Report and Literature Review. Healthcare (Basel) 2022; 10:470. [PMID: 35326948 PMCID: PMC8956084 DOI: 10.3390/healthcare10030470] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/21/2022] [Accepted: 03/01/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND/OBJECTIVE Brachial artery aneurysm (BAA) is a serious complication in patients with previous arterio-venous fistula (AVF), renal transplantation (RT), and immunosuppressive regimens. Until now, there has been no standard of care for these patients, especially for patients undergoing chronic dialysis and immunosuppressive treatment. The aim of this study was to investigate data from the literature regarding these patients and to suggest recommendations for the best approach to their treatment. METHODS A review of the literature was performed by searching the PubMed database in the English language. The review was accompanied by two case reports. A total of 24 articles with different variables-demographics, renal transplantation, aneurysm size, and type of surgery-were subjected to the review. In addition, two cases are reported. CONCLUSION This review suggests that the best treatment for these patients is open surgery, with aneurysmectomy and graft interposition. RESULTS All patients had RT. The age of patients ranged from 26-77 yo, with a male predominance. The majority had an AVF ligated after RT. The main clinical symptoms were pain, swelling, and pulsatile mass (66%). All patients, except one, were treated through open surgery. The first option for treatment was reversed saphenous vein graft interposition (36%), followed by ePTFE graft (16%).
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Affiliation(s)
- Sorin Barac
- Department of Vascular Surgery, Research Centre for Vascular and Endovascular Surgery, “Victor Babes” University of Medicine and Pharmacy Timisoara, 300041 Timisoara, Romania;
| | - Andreea Luciana Rata
- Department of Vascular Surgery, Research Centre for Vascular and Endovascular Surgery, “Victor Babes” University of Medicine and Pharmacy Timisoara, 300041 Timisoara, Romania;
| | - Alexandra Ioana Popescu
- Hospital Centre “Saint Nicolas”, “Victor Babes” University of Medicine and Pharmacy Timisoara, 57400 Sarrebourg, France;
| | - Roxana Ramona Onofrei
- Department of Rehabilitation, Physical Medicine and Rheumatology, “Victor Babes” University of Medicine and Pharmacy Timisoara, Research Center for Assessment of Human Motion, Functionality and Disability, 300041 Timisoara, Romania;
| | - Sorin Dan Chiriac
- 3rd Surgery Department, “Victor Babes” University of Medicine and Pharmacy Timisoara, 300041 Timisoara, Romania;
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Guo N, Pan ZJ, Tian J. Comparison of arteriovenous fistulas constructed with main or internal branch of the cephalic vein: a retrospective analysis of 32 cases. J Int Med Res 2021; 49:3000605211053725. [PMID: 34670421 PMCID: PMC8543713 DOI: 10.1177/03000605211053725] [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] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE To evaluate the effect on the maturation of arteriovenous fistulas (AVFs) when using the internal branch of the cephalic vein compared with the main branch of the cephalic vein. METHODS The study enrolled patients with end-stage renal disease and divided them into an internal branch group (AVF constructed using the internal branch of the cephalic vein) or a main branch group (AVF constructed using the main branch of the cephalic vein). The surgical outcomes including complications were observed in these patients after 12 weeks. RESULTS Thirty-two patients with end-stage renal disease were included in the study. There were 16 patients in each group. The demographic and clinical characteristics were not significantly different between the two groups. The diameter of the arteries and veins were not significantly different between the two groups before the operation. In the internal branch group, significantly more (n = 7) patients failed to mature or required surgical intervention compared with the main branch group (n = 1). CONCLUSION For veins of the same diameter, these findings suggest that constructing AVFs using the main branch of the cephalic vein instead of the internal branch was more suitable for patients with end-stage renal disease requiring haemodialysis.
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Affiliation(s)
- Ning Guo
- Department of Blood Purification, Qilu Hospital, Medical School of Shandong University, Jinan, Shandong Province, China
| | - Zhong-Jian Pan
- Department of Blood Purification, Qilu Hospital, Medical School of Shandong University, Jinan, Shandong Province, China
| | - Jun Tian
- Department of Blood Purification, Qilu Hospital, Medical School of Shandong University, Jinan, Shandong Province, China
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Zha D, Yang X, Yang Y, Zhang H, Jin Y, Li N, Zhou Y. The Impact of Multidisciplinary Collaborative Nursing Intervention on Arteriovenous Fistula in Patients Undergoing Hemodialysis. Clin Nurs Res 2021; 31:1158-1163. [PMID: 34384273 DOI: 10.1177/10547738211037132] [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: 10/20/2022]
Abstract
This study was conducted to evaluate the effect of multidisciplinary collaborative nursing intervention on AVF in patients with chronic kidney disease (CKD) undergoing hemodialysis. Patients (n = 84) with CKD who underwent the first autologous AVF were randomly divided into control group and multidisciplinary collaborative nursing intervention (MCNI) group and they received routine nursing procedure and multidisciplinary collaborative nursing intervention procedure, respectively. The natural blood flow and vessel diameter in MCNI group were higher than that in control group at the fourth week after surgery (p < .05). The vessel diameter in MCNI group at 2 and 4 weeks after operation was significantly larger than that in control group (p < .05).In conclusions, the implementation of multidisciplinary collaborative nursing intervention procedure can significantly promote the maturation of AVF, effectively increase the blood flow of AVF and promote the growth of vessel diameter.
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Affiliation(s)
- Danfeng Zha
- Department of Nephrology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xionghao Yang
- Department of Nephrology, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yan Yang
- Shanghai Jiao Tong University, School of Nursing, Shanghai, China
| | - Haifen Zhang
- Department of Nephrology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Jin
- Department of Nephrology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Na Li
- Department of Nephrology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yin Zhou
- Department of Nephrology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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11
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van Haaften EE, Quicken S, Huberts W, Bouten CVC, Kurniawan NA. Computationally guided in-vitro vascular growth model reveals causal link between flow oscillations and disorganized neotissue. Commun Biol 2021; 4:546. [PMID: 33972658 PMCID: PMC8110791 DOI: 10.1038/s42003-021-02065-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 03/31/2021] [Indexed: 02/03/2023] Open
Abstract
Disturbed shear stress is thought to be the driving factor of neointimal hyperplasia in blood vessels and grafts, for example in hemodialysis conduits. Despite the common occurrence of neointimal hyperplasia, however, the mechanistic role of shear stress is unclear. This is especially problematic in the context of in situ scaffold-guided vascular regeneration, a process strongly driven by the scaffold mechanical environment. To address this issue, we herein introduce an integrated numerical-experimental approach to reconstruct the graft-host response and interrogate the mechanoregulation in dialysis grafts. Starting from patient data, we numerically analyze the biomechanics at the vein-graft anastomosis of a hemodialysis conduit. Using this biomechanical data, we show in an in vitro vascular growth model that oscillatory shear stress, in the presence of cyclic strain, favors neotissue development by reducing the secretion of remodeling markers by vascular cells and promoting the formation of a dense and disorganized collagen network. These findings identify scaffold-based shielding of cells from oscillatory shear stress as a potential handle to inhibit neointimal hyperplasia in grafts.
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Affiliation(s)
- Eline E van Haaften
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sjeng Quicken
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Wouter Huberts
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Carlijn V C Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, The Netherlands.
| | - Nicholas A Kurniawan
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, The Netherlands
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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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13
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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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14
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Longitudinal computational fluid dynamics study of stenosis and aneurysmal degeneration of an aortorenal bypass. Biomech Model Mechanobiol 2020; 19:1965-1975. [PMID: 32200478 DOI: 10.1007/s10237-020-01320-9] [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: 10/16/2019] [Accepted: 03/12/2020] [Indexed: 02/05/2023]
Abstract
Saphenous vein graft (SVG) bypass placement is regarded as the optimal option for renal artery stenosis, which usually causes secondary hypertension and poor renal perfusion. Using computational fluid dynamics, this study aimed to investigate the underlying hemodynamic mechanism of the vein aneurysm and stenosis after aortorenal bypass surgery. Three-dimensional models were reconstructed based on computed tomographic angiography images of a 20-year-old female patient who suffered from uncontrollable hypertension using the image processing package Mimics (Materialise). The morphology and hemodynamic parameters in the healthy state, at initial presentation and at post-operative 9-month and 2-year follow-ups after surgery were analysed. The hemodynamic parameters became normal in the left and right renal arteries after bypass surgery. However, flow separation and stagnation occurred at the post-operative 9-month aorta-vein anastomosis, which caused asymmetrical flow and extremely high wall shear stress (WSS) and WSS gradients at the outflow vein tract, where the stenosis occurred 2 years later. In addition, the graft bending produced an asymmetrical flow pattern downstream. This research revealed that the abnormal hemodynamics, including flow separation and extremely high WSS values and gradients, caused by the retrograde flow of aortorenal bypass may be responsible for the SVG degeneration. In addition, flow asymmetry due to vessel bending is a potential risk factor for SVG aneurysm dilation.
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15
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Cunnane CV, Cunnane EM, Moran DT, Walsh MT. The presence of helical flow can suppress areas of disturbed shear in parameterised models of an arteriovenous fistula. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3259. [PMID: 31483945 DOI: 10.1002/cnm.3259] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 07/17/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
Areas of disturbed shear that develop following arteriovenous fistula (AVF) creation are believed to trigger the onset of intimal hyperplasia (IH), leading to AVF dysfunction. The presence of helical flow can suppress the flow disturbances that lead to disturbed shear in other areas of the vasculature. However, the relationship between helical flow and disturbed shear remains unevaluated in AVF. In this study, computational fluid dynamics (CFD) is used to evaluate the relationship between geometry, helical flow, and disturbed shear in parameterised models of an AVF characterised by four different anastomosis angles. The AVF models with a small anastomosis angle demonstrate the lowest distribution of low/oscillating shear and are characterised by a high helical intensity coupled with a strong balance between helical structures. Contrastingly, the models with a large anastomosis angle experience the least amount of high shear, multidirectional shear, as well as spatial and temporal gradients of shear. Furthermore, the intensity of helical flow correlates strongly with curvature (r = 0.73, P < .001), whereas it is strongly and inversely associated with taper (r = -0.87, P < .001). In summary, a flow field dominated by a high helical intensity coupled with a strong balance between helical structures can suppress exposure to low/oscillating shear but is ineffective when it comes to other types of shear. This highlights the clinical potential of helical flow as a diagnostic marker of exposure to low/oscillating shear, as helical flow can be identified in vivo with the use of ultrasound imaging.
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Affiliation(s)
- Connor V Cunnane
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Eoghan M Cunnane
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Daniel T Moran
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
| | - Michael T Walsh
- Bio Materials Research Centre, Bernal Institute, School of Engineering, Health Research Institute (HRI), University of Limerick, Limerick, Ireland
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16
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Giordano G, Giannikouris IE, Viganò S, Bacchini G. Vascular access donor artery dilatation: Considerations about the formation mechanism in immunosuppressed patient. J Vasc Access 2018. [PMID: 29529931 DOI: 10.1177/1129729817747542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Giovanni Giordano
- 1 Department of Cardio-Thoracic and Respiratory Science, University of Campania "Luigi Vanvitelli", Naples, Italy
| | | | - Sara Viganò
- 3 Department of Nephrology and Dialysis, A. Manzoni Hospital, Lecco, Italy
| | - Giuseppe Bacchini
- 3 Department of Nephrology and Dialysis, A. Manzoni Hospital, Lecco, Italy
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17
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Marticorena RM, Dacouris N, Donnelly SM. Randomized pilot study to compare metal needles versus plastic cannulae in the development of complications in hemodialysis access. J Vasc Access 2018; 19:272-282. [PMID: 29772982 PMCID: PMC6161775 DOI: 10.1177/1129729817747535] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Hemodialysis requires needle insertions every treatment. Needle injury (mechanical or hemodynamic) may cause complications (aneurysms/stenosis) that compromise dialysis delivery requiring interventions. Metal needles have a sharp slanted "V"-shaped cutting tip; plastic cannulae have a dull round tip and four side holes. Preliminary observations demonstrated a difference in intradialytic blood flow images and mean Doppler velocities at cannulation sites between the two devices. Complications from mechanical and hemodynamic trauma requiring interventions were compared in each group. MATERIALS AND METHODS In all, 33 patients (13 females and 17 new accesses) were randomized to metal group (n = 17) and plastic group (n = 16). Mechanical trauma was minimized by having five nurses performing ultrasound-guided cannulations. Complications were identified by the clinician and addressed by the interventionalists, both blinded to study participation. Patients were followed for up to 12 months. RESULTS Baseline characteristics were not significant. Procedures to treat complications along cannulation segments increased from 0.41 to 1.29 per patient (metal group) and decreased from 1.25 to 0.69 per patient (plastic group; p = 0.004). The relative risks of having an intervention (relative risk = 1.5, 95% confidence interval = 0.88-2.67) and having an infiltration during hemodialysis (relative risk = 2.26, 95% confidence interval = 1.03-4.97) were higher for metal needles. Time to first intervention trended in favor of plastic cannula (p = 0.069). Cost of supplies for these interventions was approximately CAD$20,000 lower for the plastic group. CONCLUSION Decreased burden of illness related to cannulation (less infiltrations during hemodialysis) and Qb were associated with plastic cannulae. Decreased procedure costs were suggested during the study period in the plastic group.
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Affiliation(s)
- Rosa M Marticorena
- 1 Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,2 St. Michael's Hospital, Toronto, ON, Canada.,3 William Osler Health System, Brampton, ON, Canada
| | | | - Sandra M Donnelly
- 3 William Osler Health System, Brampton, ON, Canada.,4 University of Toronto, Toronto, ON, Canada.,5 Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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18
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Wilmink T, Powers S, Hollingworth L, Stevenson T. Effect of first cannulation time and dialysis machine blood flows on survival of arteriovenous fistulas. Nephrol Dial Transplant 2017; 33:841-846. [DOI: 10.1093/ndt/gfx278] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 08/13/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Teun Wilmink
- Department of Vascular Surgery, Birmingham Heartlands Hospital, Birmingham, UK
| | - Sarah Powers
- Renal Medicine, Heart of England NHS Foundation Trust, Birmingham, UK
| | - Lee Hollingworth
- Renal Medicine, Heart of England NHS Foundation Trust, Birmingham, UK
| | - Tamasin Stevenson
- Renal Medicine, Heart of England NHS Foundation Trust, Birmingham, UK
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19
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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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20
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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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21
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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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22
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Browne LD, Walsh MT, Griffin P. Experimental and Numerical Analysis of the Bulk Flow Parameters Within an Arteriovenous Fistula. Cardiovasc Eng Technol 2015; 6:450-62. [PMID: 26577478 DOI: 10.1007/s13239-015-0246-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 09/16/2015] [Indexed: 11/25/2022]
Abstract
The creation of an arteriovenous fistula for hemodialysis has been reported to generate unstable to turbulent flow behaviour. On the other hand, the vast majority of computational fluid dynamic studies of an arteriovenous fistula use low spatial and temporal resolutions resolution in conjunction with laminar assumptions to investigate bulk flow and near wall parameters. The objective of the present study is to investigate if adequately resolved CFD can capture instabilities within an arteriovenous fistula. An experimental model of a representative fistula was created and the pressure distribution within the model was analysed for steady inlet conditions. Temporal CFD simulations with steady inflow conditions were computed for comparison. Following this verification a pulsatile simulation was employed to assess the role of pulsatility on bulk flow parameters. High frequency fluctuations beyond 100 Hz were found to occupy the venous segment of the arteriovenous fistula under pulsatile conditions and the flow within the venous segment exhibited unstable behaviour under both steady and pulsatile inlet conditions. The presence of high frequency fluctuations may be overlooked unless adequate spatial and temporal resolutions are employed. These fluctuations may impact endothelial cell function and contribute to the cascade of events leading to aggressive intimal hyperplasia and the loss of functionality of the vascular access.
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Affiliation(s)
- Leonard D Browne
- Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, Centre for Applied Biomedical Engineering Research (CABER), University of Limerick, Limerick, Ireland
| | - Michael T Walsh
- Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, Centre for Applied Biomedical Engineering Research (CABER), University of Limerick, Limerick, Ireland
| | - Philip Griffin
- Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, Centre for Applied Biomedical Engineering Research (CABER), University of Limerick, Limerick, Ireland.
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23
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Shi Y, Zhu M, Cheng J, Zhang J, Ni Z. Venous stenosis in chronic dialysis patients with a well-functioning arteriovenous fistula. Vascular 2015; 24:25-30. [PMID: 25725216 DOI: 10.1177/1708538115575649] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Purpose It is not clear whether patient who is dialyzing with a well-functioning vascular access may appear venous stenosis. The aim is to see the prevalence of central or other vein stenoses/occlusions in patients with asymptomatic, normal functioning fistulas. Methods A total of 54 patients met the inclusion criteria. We performed angiography examinations for these patients and reviewed venography of the superficial and deep venous systems. Results Among these patients, 21 (39%) were detected positive cases by the angiography, the remainder was negative cases. Thirteen of 54 (24%) had mild central venous stenosis (stenosis <50% diameter with or without collateral branch), 7/54 (13%) had upper arm vein system occlusion or stenosis, another one had anastomotic stenosis. There were no differences in fistula flow dynamics between those with venous abnormalities and those without such as blood flow rate, venous pressures, brachial arterial velocity, and brachial arterial flow rate. We also observed no significant differences in other variables between these two groups (including BMI, hemoglobin, albumin, gender, primary disease, URR, spKt/V P > 0.05). Conclusion The frequency of venous lesion is not low in hemodialysis patients with a well-functioning AVF. To value the impact of these abnormalities on access, prognosis needs longer time follow-up.
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Affiliation(s)
- Yaxue Shi
- Vascular Surgery Department, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Mingli Zhu
- Renal Department, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Jiejun Cheng
- Radiology Department, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Jiwei Zhang
- Vascular Surgery Department, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Zhaohui Ni
- Renal Department, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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24
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Boghosian M, Cassel K, Hammes M, Funaki B, Kim S, Qian X, Wang X, Dhar P, Hines J. Hemodynamics in the cephalic arch of a brachiocephalic fistula. Med Eng Phys 2014; 36:822-30. [PMID: 24695337 DOI: 10.1016/j.medengphy.2014.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 01/22/2014] [Accepted: 03/08/2014] [Indexed: 12/01/2022]
Abstract
The care and outcome of patients with end stage renal disease (ESRD) on chronic hemodialysis is directly dependent on their hemodialysis access. A brachiocephalic fistula (BCF) is commonly placed in the elderly and in patients with a failed lower-arm, or radiocephalic, fistula. However, there are numerous complications such that the BCF has an average patency of only 3.6 years. A leading cause of BCF dysfunction and failure is stenosis in the arch of the cephalic vein near its junction with the axillary vein, which is called cephalic arch stenosis (CAS). Using a combined clinical and computational investigation, we seek to improve our understanding of the cause of CAS, and to develop a means of predicting CAS risk in patients with a planned BCF access. This paper details the methodology used to determine the hemodynamic consequences of the post-fistula environment and illustrates detailed results for a representative sample of patient-specific anatomies, including a single, bifurcated, and trifurcated arch. It is found that the high flows present due to fistula creation lead to secondary flows in the arch owing to its curvature with corresponding low wall shear stresses. The abnormally low wall shear stress locations correlate with the development of stenosis in the singular case that is tracked in time for a period of one year.
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Affiliation(s)
- M Boghosian
- Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, United States.
| | - K Cassel
- Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, United States
| | - M Hammes
- Nephrology, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - B Funaki
- Vascular and Interventional Radiology, Department of Medicine, University of Chicago Medical Center, Chicago, IL, United States
| | - S Kim
- Vascular and Interventional Radiology, Department of Medicine, University of Chicago Medical Center, Chicago, IL, United States
| | - X Qian
- Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, United States
| | - X Wang
- Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, United States
| | - P Dhar
- Biomedical Engineering Department, Illinois Institute of Technology, Chicago, IL, United States
| | - J Hines
- Nephrology, Department of Medicine, University of Chicago, Chicago, IL, United States
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McGah PM, Leotta DF, Beach KW, Eugene Zierler R, Aliseda A. Incomplete restoration of homeostatic shear stress within arteriovenous fistulae. J Biomech Eng 2014; 135:011005. [PMID: 23363216 DOI: 10.1115/1.4023133] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Arteriovenous fistulae are surgically created to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is, in part, a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. We present computational hemodynamic simulations in four patient-specific models of mature arteriovenous fistulae reconstructed from 3D ultrasound scans. Our results suggest that these mature fistulae have remodeled to return to ''normal'' shear stresses away from the anastomoses: about 1.0 Pa in the outflow veins and about 2.5 Pa in the inflow arteries. Large parts of the anastomoses were found to be under very high shear stresses >15 Pa, over most of the cardiac cycle. These results suggest that the remodeling process works toward restoring mechanical homeostasis in the fistulae, but that the process is limited or incomplete, even in mature fistulae, as evidenced by the elevated shear at or near the anastomoses. Based on the long term clinical viability of these dialysis accesses, we hypothesize that the elevated nonhomeostatic shear stresses in some portions of the vessels were not detrimental to fistula patency.
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Affiliation(s)
- Patrick M McGah
- Department of Mechanical Engineering, University of Washington, Stevens Way, Box 352600, Seattle, WA 98195, USA.
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26
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Remuzzi A, Ene-Iordache B. Novel paradigms for dialysis vascular access: upstream hemodynamics and vascular remodeling in dialysis access stenosis. Clin J Am Soc Nephrol 2013; 8:2186-93. [PMID: 23990161 PMCID: PMC3848396 DOI: 10.2215/cjn.03450413] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Failure of hemodialysis access is caused mostly by venous intimal hyperplasia, a fibro-muscular thickening of the vessel wall. The pathogenesis of venous neointimal hyperplasia in primary arteriovenous fistulae consists of processes that have been identified as upstream and downstream events. Upstream events are the initial events producing injury of the endothelial layer (surgical trauma, hemodynamic shear stress, vessel wall injury due to needle punctures, etc.). Downstream events are the responses of the vascular wall at the endothelial injury that consist of a cascade of processes including leukocyte adhesion, migration of smooth muscle cells from the media to the intimal layer, and proliferation. In arteriovenous fistulae, the stenoses occur in specific sites, consistently related to the local hemodynamics determined by the vessel geometry and blood flow pattern. Recent findings that the localization of these sites matches areas of disturbed flow may add new insights into the pathogenesis of neointimal hyperplasia in the venous side of vascular access after the creation of the anastomosis. The detailed study of fluid flow motion acting on the vascular wall in anastomosed vessels and in the arm vasculature at the patient-specific level may help to elucidate the role of hemodynamics in vascular remodeling and neointimal hyperplasia formation. These computational approaches may also help in surgical planning for the amelioration of clinical outcome. This review aims to discuss the role of the disturbed flow condition in acting as upstream event in the pathogenesis of venous intimal hyperplasia and in producing subsequent local vascular remodeling in autogenous arteriovenous fistulae used for hemodialysis access. The potential use of blood flow analysis in the management of vascular access is also discussed.
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Affiliation(s)
- Andrea Remuzzi
- Biomedical Engineering Department, IRCCS - Istituto di Ricerche Farmacologiche “Mario Negri,” Bergamo, Italy; and
- Engineering Department, University of Bergamo, Bergamo, Italy
| | - Bogdan Ene-Iordache
- Biomedical Engineering Department, IRCCS - Istituto di Ricerche Farmacologiche “Mario Negri,” Bergamo, Italy; and
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27
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Rajabi-Jagahrgh E, Roy-Chaudhury P, Wang Y, Al-Rjoub M, Campos-Naciff B, Choe A, Dumoulin C, Banerjee RK. New techniques for determining the longitudinal effects of local hemodynamics on the intima-media thickness in arteriovenous fistulae in an animal model. Semin Dial 2013; 27:424-35. [PMID: 24261988 DOI: 10.1111/sdi.12162] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Remodeling in the arteriovenous fistulas (AVFs) is believed to be a hemodynamic-driven process, which results in extreme changes in the diameter and intima-media thickening (IMT) of vessels over time. This study aims to describe the successful development of techniques that enabled correlation of changes in local and longitudinal wall shear stress (WSS) with the temporal variations of the diameter and IMT in the venous segment of AVFs. An AVF was created between the femoral artery and vein of a 50-kg pig. We have previously shown the successful use of CT-scan and ultrasound techniques for anatomical and flow measurements in AVFs, respectively. In this study, we developed new techniques involving markers (both in vivo and ex vivo), casting (ex vivo), and micro-MRI (ex vivo; 7 Tesla). A radiopaque marker (ROM) was sutured to the AVF at the day of surgery, which was visible in the CT-scan images, micro-MRI, and histology sections. Therefore, ROM served as a fixed local reference for both in vivo and ex vivo states of AVFs. Immediately after sacrificing the pig, a procedure was developed to create a cast from the AVF and thus, maintaining the in vivo state of the AVF during the histology process. Then, micro-MRI and histology techniques were conducted on the AVF to measure IMT in the vein. Along the ROM, the local changes in WSS levels for two cross-sections were tracked at 2D (D: days) and 28D post surgery. WSS levels reduced from 2D to 28D for both cross-sections. Also, the recirculation zones, which formed at 2D for both sections, became smaller in size at 28D. These hemodynamic changes were then mapped onto the corresponding IMT measurements from histology and micro-MRI. It was observed that the recirculation zones at 2D and 28D corresponded to the largest IMT in the two sections. In summary, the new methodologies allowed us to define a fixed local reference at all time points in the AVF, which enabled accurate tracking of local changes in hemodynamics (WSS), configuration (diameter), and structure (IMT) of the venous segment over time. This also empowered study of the interactions between these parameters, which could improve our understanding about the hemodynamic-driven remodeling in AVFs. From a clinical point of view, this information could be translated into local and early therapeutic interventions for dialysis patients.
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Affiliation(s)
- Ehsan Rajabi-Jagahrgh
- Mechanical Engineering Program, School of Dynamic Systems, University of Cincinnati, Cincinnati, Ohio
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McGah PM, Leotta DF, Beach KW, Aliseda A. Effects of wall distensibility in hemodynamic simulations of an arteriovenous fistula. Biomech Model Mechanobiol 2013; 13:679-95. [PMID: 24037281 DOI: 10.1007/s10237-013-0527-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/30/2013] [Indexed: 11/24/2022]
Abstract
Arteriovenous fistulae are created surgically to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is in part a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. The current study presents fluid-structure interaction (FSI) simulations of a patient-specific model of a mature arteriovenous fistula reconstructed from 3D ultrasound scans. The FSI results are compared with previously published data of the same model but with rigid walls. Ultrasound-derived wall motion measurements are also used to validate the FSI simulations of the wall motion. Very large time-averaged shear stresses, 10-15 Pa, are calculated at the fistula anastomosis in the FSI simulations, values which are much larger than what is typically thought to be the normal homeostatic shear stress in the peripheral vasculature. Although this result is systematically lower by as much as 50% compared to the analogous rigid-walled simulations, the inclusion of distensible vessel walls in hemodynamic simulations does not reduce the high anastomotic shear stresses to "normal" values. Therefore, rigid-walled analyses may be acceptable for identifying high shear regions of arteriovenous fistulae.
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Affiliation(s)
- Patrick M McGah
- Department of Mechanical Engineering, University of Washington, Seattle, WA, 98115, USA,
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A Computational Study of the Factors Influencing Pressure in Arteriovenous Fistulae Venous Aneurysms. J Vasc Access 2013; 14:325-9. [DOI: 10.5301/jva.5000144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/01/2013] [Indexed: 11/20/2022] Open
Abstract
Purpose To investigate the factors influencing the hydrostatic pressure exerted within the venous aneurysms (VA) of an arteriovenous fistula (AVF). Methods Ideal models of a side-to-end brachial-cephalic AVF were computationally constructed and typical values for the length and the local diameters were considered for both the artery and vein sections of the models. Three VA configurations were reconstructed (spherical, fusiform and curved) and hydrostatic pressure was assessed with respect to different degrees of the outflow vein stenosis, ranging from 25% to 95%, and VA maximum diameters, using validated, commercially available software. Results The pressure in the VA was steady (1200 Pa) for venous outflow stenoses up to 75%. For stenoses greater than 75% a exponential pressure rise was observed, reaching 1500 Pa for stenoses of 95%. Neither the VA configuration nor its maximum diameter affected the pressure values exerted within the VA or the point of the pressure upstroke. Conclusions our study supports the presence of a critical stenotic outflow vein diameter beyond which there is an exponential VA pressure increase, influenced neither by the shape nor the size of the VA. Whether the prompt, non-invasive detection of this finding can contribute or lead to the determination of a criterion for early intervention in VAs before clinical complications are developed, should be investigated by future studies.
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Fulker D, Kang M, Simmons A, Barber T. The flow field near a venous needle in hemodialysis: a computational study. Hemodial Int 2013; 17:602-11. [PMID: 23448433 DOI: 10.1111/hdi.12029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 01/16/2013] [Indexed: 11/30/2022]
Abstract
The vascular access used in hemodialysis can suffer from numerous complications, which may lead to failure of the access, patient morbidity, and significant costs. The flow field in the region of the venous needle may be a source of damaging hemodynamics and hence adverse effects on the fistula. In this study, the venous needle flow has been considered, using three-dimensional computational methods. Four scenarios where the venous needle flow could potentially influence dialysis treatment outcome were identified and examined: Variation of the needle placement angle (10°, 20°, 30°), variation of the blood flow rate settings (200, 300, 400 mL/min), variation of the needle depth (top, middle, bottom), and the inclusion of a back eye in the needle design. The presence of the needle has significant effect on the flow field, with different scenarios having varying influence. In general, wall shear stresses were elevated above normal physiological values, and increased presence of areas of low velocity and recirculation-indicating increased likelihood of intimal hyperplasia development-were found. Computational results showed that the presence of the venous needle in a hemodialysis fistula leads to abnormal and potentially damaging flow conditions and that optimization of needle parameters could aid in the reduction of vascular access complications. Results indicate shallow needle angles and lower blood flow rates may minimize vessel damage.
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Affiliation(s)
- David Fulker
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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Abstract
Hemodynamic parameters play an important role in regulating vascular remodeling in arterio-venous fistula (AVF) maturation. Investigating the changes in hemodynamic parameters during AVF maturation is expected to improve our understanding of fistula failure, but very little data on actual temporal changes in human AVFs is available. The present study aimed to assess the feasibility of using a noncontrast-enhanced MRI protocol combined with CFD modeling to relate hemodynamic changes to vascular remodeling following native AVF placement. MR angiography (MRA) and MR velocimetry (MRV) data was acquired peri-operatively, 1 month, and 3 months later in three patients. Vascular geometries were obtained by segmentation of the MRA images. Pulsatile flow simulations were performed in the patient specific vascular geometries with time-dependent boundary conditions prescribed from MRV measurements. A principal result of the study is the description of WSS changes over time in the same patients. The disturbed flow observed in the venous segments resulted in a variability of the WSS distribution and could be responsible for the non-uniform remodeling of the vessel. The artery did not show regions of disturbed flow upstream from the anastomosis, which would be consistent with the uniform remodeling. MRI use demonstrated the ability to provide a comprehensive evaluation of clinically relevant information for the investigation of upper extremity AVFs. 3D geometry from MRA in combination with MRV provides the opportunity to perform detailed CFD analysis of local hemodynamics in order to determine flow descriptors affecting fistula maturation.
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An Overview of the Hemodynamic Aspects of the Blood Flow in the Venous Outflow Tract of the Arteriovenous Fistula. J Vasc Access 2012; 13:271-8. [DOI: 10.5301/jva.5000037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2011] [Indexed: 11/20/2022] Open
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Rajabi-Jagahrgh E, Krishnamoorthy MK, Roy-Chaudhury P, Succop P, Wang Y, Choe A, Banerjee RK. Longitudinal assessment of hemodynamic endpoints in predicting arteriovenous fistula maturation. Semin Dial 2012; 26:208-15. [PMID: 22892020 DOI: 10.1111/j.1525-139x.2012.01112.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Arteriovenous fistula (AVF) nonmaturation is currently a significant clinical problem; however, the mechanisms responsible for this have remained unanswered. Previous work by our group and others has suggested that anatomical configuration and the corresponding hemodynamic endpoints could have an important role in AVF remodeling. Thus, our goal was to assess the longitudinal (temporal) effect of wall shear stress (WSS) on remodeling process of AVFs with two different configurations. The hypothesis is that early assessment of hemodynamic endpoints such as temporal gradient of WSS will predict the maturation status of AVF at later time points. Two AVFs with curved (C-AVF) and straight (S-AVF) configurations were created between the femoral artery and vein of each pig. Three pigs were considered in this study and in total six AVFs (three C-AVF and three S-AVF) were created. The CT scan and ultrasound were utilized to numerically evaluate local WSS at 20 cross-sections along the venous segment of AVFs at 2D (D: days), 7D, and 28D postsurgery. These cross-sections were located at 1.5 mm increments from the anastomosis junction. Local WSS values at these cross-sections were correlated with their corresponding luminal area over time. The WSS in C-AVF decreased from 22.3 ± 4.8 dyn/cm(2) at 2D to 4.1 ± 5.1 dyn/cm(2) at 28D, while WSS increased in S-AVF from 13.0 ± 5.0 dyn/cm(2) at 2D to 36.7 ± 5.3 dyn/cm(2) at 28D. Corresponding to these changes in WSS levels, luminal area of C-AVF dilated (0.23 ± 0.14 cm(2) at 2D to 0.87 ± 0.14 cm(2) at 28D) with attendant increase in flow rate. However, S-AVF had minimal changes in area (0.26 ± 0.02 cm(2) at 2D to 0.27 ± 0.03 cm(2) at 28D) despite some increase in flow rate. Our results suggest that the temporal changes of WSS could have significant effects on AVF maturation. Reduction in WSS over time (regardless of initial values) may result in dilation (p < 0.05), while increase in WSS may be detrimental to maturation. Thus, creation of AVFs in a specific configuration which results in a decline in WSS over time may reduce AVF maturation failure.
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Affiliation(s)
- Ehsan Rajabi-Jagahrgh
- Mechanical Engineering Program, School of Dynamic Systems, University of Cincinnati, Cincinnati, Ohio, USA
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Sia SF, Qian Y, Zhang Y, Morgan MK. Mean Arterial Pressure Required for Maintaining Patency of Extracranial-to-Intracranial Bypass Grafts. Neurosurgery 2012; 71:826-31. [DOI: 10.1227/neu.0b013e318266e6c2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
BACKGROUND:
Maintaining flow in a newly established high-flow bypass into the intracranial circulation may be threatened by low blood pressure.
OBJECTIVE:
To identify mean arterial blood pressure below which early graft failure may ensue.
METHODS:
Computational fluid dynamic blood flow simulation and Doppler ultrasound–derived velocities were combined to study 12 patients with common carotid–to–intracranial (internal carotid artery in 9 and middle cerebral artery in 3) arterial brain bypass with interposition of the saphenous vein. Patients underwent carotid duplex and high-resolution computed tomography angiography to obtain the necessary data. A mean time-averaged pressure gradient across both anastomoses of the graft was then calculated.
RESULTS:
The bypass graft mean blood flow ± SD was 180.3 ± 76.2 mL/min (95% confidence interval: 132–229). The mean time-averaged pressure gradient ± SD across the bypass graft was 10.2 ± 8.7 mm Hg (95% confidence interval: 4.6-15.7). This compared with a mean pressure gradient ± SD on the contralateral carotid of 21.7 ± 13.8 mm Hg. From these data, the minimum mean ± SD systemic pressure necessary to maintain graft flow of at least 40 mL/min was 61.6 ± 2.31 mm Hg, and the mean peak wall shear stress ± SD at the proximal anastomosis was 0.8 ± 0.7 Pa (95% confidence interval: 0.3-1.2).
CONCLUSION:
Early postoperative mean arterial pressure less than approximately 60 mm Hg may induce blood flow in the bypass to decrease to less than 40 mL/min, a flow below which low shear stress may lead to early graft occlusion.
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Affiliation(s)
- Sheau Fung Sia
- Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Yi Qian
- Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Yu Zhang
- Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
| | - Michael Kerin Morgan
- Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales, Australia
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Ene-Iordache B, Remuzzi A. Disturbed flow in radial-cephalic arteriovenous fistulae for haemodialysis: low and oscillating shear stress locates the sites of stenosis. Nephrol Dial Transplant 2011; 27:358-68. [PMID: 21771751 DOI: 10.1093/ndt/gfr342] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Despite recent clinical and technological advancements, the vascular access (VA) for haemodialysis still has significant early failure rates after arteriovenous fistula (AVF) creation. VA failure is mainly related to the haemodynamic conditions that trigger the phenomena of vascular wall disease such as intimal hyperplasia (IH) or atherosclerosis. METHODS We performed transient computational fluid dynamics simulations within idealized three-dimensional models of 'end-to-side' and 'end-to-end' radio-cephalic anastomosis, using non-Newtonian blood and previously measured flows and division ratio in subjects requiring primary access procedure as boundary conditions. RESULTS The numerical simulations allowed full characterization of blood flow inside the AVF and of patterns of haemodynamic shear stress, known to be the major determinant of vascular remodelling and disease. Wall shear stress was low and oscillating in zones where flow stagnation occurs on the artery floor and on the inner wall of the juxta-anastomotic vein. CONCLUSIONS Zones of low and oscillatory shear stress were located in the same sites where luminal reduction was documented in previous experimental studies on sites stenosis distribution in AVF. We conclude that even when exposed to high flow rates, there are spot regions along the AVF exposed to athero-prone shear stress that favour vessel stenosis by triggering IH.
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Affiliation(s)
- Bogdan Ene-Iordache
- Department of Biomedical Engineering, Laboratory of Biomedical Technologies, Mario Negri Institute for Pharmacological Research, Ranica, Italy.
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