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Drost S, Alam N, Houston JG, Newport D. Review of Experimental Modelling in Vascular Access for Hemodialysis. Cardiovasc Eng Technol 2017; 8:330-341. [PMID: 28567580 DOI: 10.1007/s13239-017-0311-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/24/2017] [Indexed: 11/25/2022]
Abstract
This paper reviews applications of experimental modelling in vascular access for hemodialysis. Different techniques that are used in in-vitro experiments are bulk pressure and flow rate measurements, Laser Doppler Velocimetry and Vector Doppler Ultrasound point velocity measurements, and whole-field measurements such as Particle Image Velocimetry, Ultrasound Imaging Velocimetry, Colour Doppler Ultrasound, and Planar Laser Induced Fluorescence. Of these methods, the ultrasound techniques can also be used in-vivo, to provide realistic boundary conditions to in-vitro experiments or numerical simulations. In the reviewed work, experimental modelling is mainly used to support computational models, but also in some cases as a tool on its own. It is concluded that, to further advance the utility of computational modelling in vascular access research, a rigorous verification and validation procedure should be adopted. Experimental modelling can play an important role in both in-vitro validation, and the quantification of the accuracy, uncertainty, and reproducibility of in-vivo measurement methods.
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Affiliation(s)
- S Drost
- School of Engineering, Bernal Institute, University of Limerick, Limerick, Ireland
| | - N Alam
- School of Engineering, Bernal Institute, University of Limerick, Limerick, Ireland
| | - J G Houston
- Molecular & Clinical Medicine, School of Medicine, University of Dundee, Dundee, Scotland, UK
| | - D Newport
- School of Engineering, Bernal Institute, University of Limerick, Limerick, Ireland.
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Ruiz-Soler A, Kabinejadian F, Slevin MA, Bartolo PJ, Keshmiri A. Optimisation of a Novel Spiral-Inducing Bypass Graft Using Computational Fluid Dynamics. Sci Rep 2017; 7:1865. [PMID: 28500311 PMCID: PMC5431846 DOI: 10.1038/s41598-017-01930-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/06/2017] [Indexed: 11/09/2022] Open
Abstract
Graft failure is currently a major concern for medical practitioners in treating Peripheral Vascular Disease (PVD) and Coronary Artery Disease (CAD). It is now widely accepted that unfavourable haemodynamic conditions play an essential role in the formation and development of intimal hyperplasia, which is the main cause of graft failure. This paper uses Computational Fluid Dynamics (CFD) to conduct a parametric study to enhance the design and performance of a novel prosthetic graft, which utilises internal ridge(s) to induce spiral flow. This design is primarily based on the identification of the blood flow as spiral in the whole arterial system and is believed to improve the graft longevity and patency rates at distal graft anastomoses. Four different design parameters were assessed in this work and the trailing edge orientation of the ridge was identified as the most important parameter to induce physiological swirling flow, while the height of the ridge also significantly contributed to the enhanced performance of this type of graft. Building on these conclusions, an enhanced configuration of spiral graft is proposed and compared against conventional and spiral grafts to reaffirm its potential benefits.
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Affiliation(s)
- Andres Ruiz-Soler
- Engineering and Materials Research Centre, Manchester Metropolitan University, Manchester, M1 5GD, UK.,School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Foad Kabinejadian
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109-2110, USA
| | - Mark A Slevin
- Healthcare Science Research Centre, Manchester Metropolitan University, Manchester, M1 5GD, UK
| | - Paulo J Bartolo
- School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK
| | - Amir Keshmiri
- School of Mechanical, Aerospace and Civil Engineering (MACE), The University of Manchester, Manchester, M13 9PL, UK.
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Numerical Assessment of Novel Helical/Spiral Grafts with Improved Hemodynamics for Distal Graft Anastomoses. PLoS One 2016; 11:e0165892. [PMID: 27861485 PMCID: PMC5115668 DOI: 10.1371/journal.pone.0165892] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 10/19/2016] [Indexed: 11/19/2022] Open
Abstract
In the present work, numerical simulations were conducted for a typical end-to-side distal graft anastomosis to assess the effects of inducing secondary flow, which is believed to remove unfavourable flow environment. Simulations were carried out for four models, generated based on two main features of 'out-of-plane helicity' and 'spiral ridge' in the grafts as well as their combination. Following a qualitative comparison against in vitro data, various mean flow and hemodynamic parameters were compared and the results showed that helicity is significantly more effective in inducing swirling flow in comparison to a spiral ridge, while their combination could be even more effective. In addition, the induced swirling flow was generally found to be increasing the wall shear stress and reducing the flow stagnation and particle residence time within the anastomotic region and the host artery, which may be beneficial to the graft longevity and patency rates. Finally, a parametric study on the spiral ridge geometrical features was conducted, which showed that the ridge height and the number of spiral ridges have significant effects on inducing swirling flow, and revealed the potential of improving the efficiency of such designs.
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Spiral Laminar Flow: a Survey of a Three-Dimensional Arterial Flow Pattern in a Group of Volunteers. Eur J Vasc Endovasc Surg 2016; 52:674-680. [DOI: 10.1016/j.ejvs.2016.07.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 07/16/2016] [Indexed: 11/18/2022]
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Kokkalis E, Aristokleous N, Houston JG. Haemodynamics and Flow Modification Stents for Peripheral Arterial Disease: A Review. Ann Biomed Eng 2015; 44:466-76. [PMID: 26467554 PMCID: PMC4764640 DOI: 10.1007/s10439-015-1483-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 10/07/2015] [Indexed: 02/02/2023]
Abstract
Endovascular stents are widely used for the treatment of peripheral arterial disease (PAD). However, the development of in-stent restenosis and downstream PAD progression remain a challenge. Stent revascularisation of PAD causes arterial trauma and introduces abnormal haemodynamics, which initiate complicated biological processes detrimental to the arterial wall. The interaction between stent struts and arterial cells in contact, and the blood flow field created in a stented region, are highly affected by stent design. Spiral flow is known as a normal physiologic characteristic of arterial circulation and is believed to prevent the development of flow disturbances. This secondary flow motion is lost in atheromatous disease and its re-introduction after endovascular treatment of PAD has been suggested as a method to induce stabilised and coherent haemodynamics. Stent designs able to generate spiral flow may support endothelial function and therefore increase patency rates. This review is focused on secondary flow phenomena in arteries and the development of flow modification stent technologies for the treatment of PAD.
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Affiliation(s)
- Efstratios Kokkalis
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom
| | - Nicolas Aristokleous
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom.
| | - J Graeme Houston
- Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Mail Box 1, Dundee, DD1 9SY, United Kingdom
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Kokkalis E, Cookson AN, Stonebridge PA, Corner GA, Houston JG, Hoskins PR. Comparison of vortical structures induced by arteriovenous grafts using vector Doppler ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:760-774. [PMID: 25683221 DOI: 10.1016/j.ultrasmedbio.2014.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 08/18/2014] [Accepted: 10/18/2014] [Indexed: 06/04/2023]
Abstract
Arteriovenous prosthetic grafts are used in hemodialysis. Stenosis in the venous anastomosis is the main cause of occlusion and the role of local hemodynamics in this is considered significant. A new spiral graft design has been proposed to stabilize the flow phenomena in the host vein. Cross-flow vortical structures in the outflow of this graft were compared with those from a control device. Both grafts were integrated in identical in-house ultrasound-compatible flow phantoms with realistic surgical configurations. Constant flow rates were applied. In-plane 2-D velocity and vorticity mapping was developed using a vector Doppler technique. One or two vortices were detected for the spiral graft and two to four for the control, along with reduced stagnation points for the former. The in-plane peak velocity and circulation were calculated and found to be greater for the spiral device, implying increased in-plane mixing, which is believed to inhibit thrombosis and neo-intimal hyperplasia.
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Affiliation(s)
- Efstratios Kokkalis
- Institute for Medical Science and Technology, University of Dundee, Dundee, UK; Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK.
| | - Andrew N Cookson
- Department of Biomedical Engineering, King's College London, London, UK
| | - Peter A Stonebridge
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - George A Corner
- Medical Physics, Ninewells Hospital and Medical School, Dundee, UK
| | - J Graeme Houston
- Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Peter R Hoskins
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
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Patterns of Blood Flow as a Predictor of Maturation of Arteriovenous Fistula for Haemodialysis. J Vasc Access 2014; 15:169-74. [DOI: 10.5301/jva.5000214] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2013] [Indexed: 11/20/2022] Open
Abstract
Purpose A palpable “thrill” is traditionally associated with success following arteriovenous fistula (AVF) surgery. A thrill typically characterizes turbulent flow and this is a paradox as turbulence is a driver of neointimal hyperplasia. Spiral laminar flow (SLF) has been described as normal and protective pattern of flow in native arteries and is associated with superior patency in bypass grafts that generate it. The aim of this study was to define the pattern of flow within AVFs immediately post-operatively and at follow-up to assess maturation. Methods Doppler ultrasound was used immediately post-operatively and at follow-up (6 weeks). Blood flow was assessed as SLF or non-SLF. Two blinded qualified observers analysed the images. Patients were followed up for 6 months. Maturation was statistically analysed against the type of flow. Results Sequential patients having AVF surgery (n=56) were assessed: 46 (82%) patients had a thrill, 3 patients had no flow and 7 patients had pulsatile flow without a palpable thrill. SLF was present in 80% of those with a thrill but not in any without a thrill (p<0.0001). At follow-up (n=51) 41, patients had a matured AVF (80%), of which 76% had SLF immediately post-operatively. Only one patient with SLF failed to mature. In the non-SLF group 5 of the 15 AVFs failed to mature (66%; p<0.005). Conclusions SLF was strongly supportive of successful fistula maturation. A “thrill” was characteristic of spiral rather than turbulence. The mechanism of this apparent beneficial effect of this pattern of flow requires further investigation.
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