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Nash TM, Elahwal M, Edwards M. Adaptation of the vein cuff in distal arterial anastomosis (Brighton Sock). Ann R Coll Surg Engl 2021; 103:537-538. [PMID: 34192499 DOI: 10.1308/rcsann.2021.0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- T M Nash
- Royal Sussex County Hospital, Brighton, UK
| | - M Elahwal
- Royal Sussex County Hospital, Brighton, UK
| | - M Edwards
- Royal Sussex County Hospital, Brighton, UK
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2
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Affiliation(s)
- G. Steinthorsson
- Department of Vascular Surgery, Yale University School of Medicine, USA
| | - B. Sumpio
- Department of Vascular Surgery, Yale University School of Medicine, USA
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3
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Loh SA, Howell BS, Rockman CB, Cayne NS, Adelman MA, Gulkarov I, Veith FJ, Maldonado TS. Mid- and long-term results of the treatment of infrainguinal arterial occlusive disease with precuffed expanded polytetrafluoroethylene grafts compared with vein grafts. Ann Vasc Surg 2012; 27:208-17. [PMID: 22998787 DOI: 10.1016/j.avsg.2012.04.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 04/03/2012] [Accepted: 04/03/2012] [Indexed: 10/27/2022]
Abstract
BACKGROUND Prosthetic grafts for lower-extremity bypass have limited patency compared with autologous vein grafts. Precuffed expanded polytetrafluoroethylene (ePTFE) grafts alter the geometry of the distal hood to improve patency. This study reports the authors' long-term results on the use of precuffed ePTFE grafts for infrainguinal bypasses in patients with arterial occlusive disease and compares these with results of reversed great saphenous vein grafts (rSVG). METHODS A retrospective review of billing codes identified 101 polytetrafluoroethylene (PTFE) and 47 rSVG bypasses performed over a 6-year period. Femoral to below-knee popliteal and femoral to tibial bypasses were analyzed. Data collected consisted of risk factors, Rutherford classification, bypass inflow and outflow, runoff vessels, patency, amputation, and death. Primary end points consisted of primary, assisted-primary, and secondary patency along with limb salvage. RESULTS Mean age of the patients was 76 years in the PTFE group and 69.8 years in the rSVG group. For femoral to below-knee popliteal bypasses, primary patency at 1, 3, and 5 years in the PTFE group was 76.9%, 48.7%, and 43.3%, respectively, compared with 77.1%, 77.1%, and 77.1%, respectively, in the rSVG group (P = 0.225). Secondary patency was 89.2%, 70.9%, and 50.6% in the PTFE group compared with 84.4%, 84.4%, and 84.4% in the rSVG group (P = 0.269). Limb salvage was similar in the PTFE compared with the rSVG group (97.7%, 90.5%, and 79.4% vs. 83.3%, 83.3%, and 83.3%; P = 0.653). For femoral to tibial bypasses, primary patency in the PTFE group at 1, 3, and 5 years was 57.1%, 40.4%, and 22.1%, respectively, compared with 67.4%, 67.4%, and 50.6%, respectively, for the rSVG group (P = 0.246). Secondary patency was 75.5%, 44.9%, and 22.7% in the PTFE group compared with 91.8%, 91.8%, and 52.5% in the rSVG group (P = 0.022). Limb salvage at 1, 3, and 5 years was 79.2%, 55.7%, and 55.7%, respectively, in the PTFE group compared with 96.4%, 96.4%, and 64.3%, respectively, in the rSVG group (P = 0.046). CONCLUSIONS Precuffed ePTFE grafts demonstrate similar 1-year patency to that of rSVG. However, mid- and long-term patency is reduced compared with saphenous vein grafts (SVG), especially to tibial targets. PTFE grafts to the popliteal demonstrate limb salvage rates similar to those of SVG. In the tibial vessels, limb salvage rates for PTFE grafts are significantly worse compared with SVG.
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Affiliation(s)
- Shang A Loh
- Division of Vascular and Endovascular Surgery, Department of Surgery, New York University School of Medicine, New York, NY 10016, USA
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4
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Twine CP, Williams IM, Fligelstone LJ. Systematic review and meta-analysis of vein cuffs for below-knee synthetic bypass. Br J Surg 2012; 99:1195-202. [PMID: 22619062 DOI: 10.1002/bjs.8811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2012] [Indexed: 11/06/2022]
Abstract
BACKGROUND The aim was to investigate the possible benefit of vein cuffs for femoral to below-knee popliteal and femorodistal vessel synthetic bypass grafts. METHODS PubMed, the Cochrane library, Embase and ClinicalTrials.gov were searched for all studies on any clinical effect of vein cuffs on synthetic grafts. Outcomes were selected based on inclusion in two or more studies: primary patency and limb survival. The data were subjected to meta-analysis by outcome. RESULTS Three cohort and two randomized studies were selected for inclusion, involving 885 patients. Meta-analysis of five studies examining below-knee popliteal bypass showed a significant improvement for primary patency in cuffed grafts at 2 years, but not at 1 or 3 years (odds ratio at 2 years 0·46, 95 per cent confidence interval 0·22 to 0·97; P = 0·04). Limb salvage was significantly improved in cuffed grafts up to 2 years. Limb survival was also improved for cuffed distal grafts at 2 years (odds ratio 0·29, 0·11 to 0·75; P = 0·01) but showed no difference at any other time interval. Study quality was generally poor, with conflicting results. CONCLUSION There was a small but significant benefit for vein cuffs on synthetic grafts used for femoral to below-knee popliteal anastomoses, but little benefit for femorodistal anastomoses.
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Affiliation(s)
- C P Twine
- Department of Vascular and Endovascular Surgery, Morriston Hospital, Swansea, UK
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5
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Chiu JJ, Chien S. Effects of disturbed flow on vascular endothelium: pathophysiological basis and clinical perspectives. Physiol Rev 2011; 91:327-87. [PMID: 21248169 PMCID: PMC3844671 DOI: 10.1152/physrev.00047.2009] [Citation(s) in RCA: 1375] [Impact Index Per Article: 105.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.
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Affiliation(s)
- Jeng-Jiann Chiu
- Division of Medical Engineering Research, National Health Research Institutes, Taiwan
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6
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Numerical Study of the Influence of Anastomotic Configuration on Hemodynamics in Miller Cuff Models. Ann Biomed Eng 2008; 37:301-14. [DOI: 10.1007/s10439-008-9617-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Accepted: 12/01/2008] [Indexed: 10/21/2022]
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7
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Gulkarov I, Malik R, Yakubov R, Gagne P, Muhs BE, Rockman C, Cayne NS, Jacobowitz GR, Lamparello PJ, Adelman MA, Maldonado TS. Early Results for Below-Knee Bypasses Using Distaflo. Vasc Endovascular Surg 2008; 42:561-6. [DOI: 10.1177/1538574408322659] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In patients who require lower extremity revascularization, prosthetic graft is a reasonable alternative in the absence of a suitable autologous vein conduit. However, prosthetic bypass grafts have limited patency, especially for infrageniculate reconstruction. Polytetrafluoroethylene grafts were geometrically modified at the distal end to increase their patency. The authors reviewed their experience with the Distaflo graft in patients who required lower extremity below-knee popliteal and tibial bypasses when no suitable autologous vein conduit was available. Chart review was conducted of the 57 patients who underwent 60 lower extremity bypasses over a 3-year period between June 2003 and April 2006. Twenty-four revascularizations were constructed to the tibial outflow sites, whereas the remaining grafts were placed to the below-knee (28) and above-knee (8) popliteal artery, respectively. Study endpoints were primary, assisted primary, secondary patency, and limb salvage at the time of follow-up. Distaflo bypass was performed at the infrageniculate level in 86.7% of cases (28 below-knee popliteal, 24 tibial). Mean follow-up time was 12 months (range, 0.5-37.5 months). At 1 year, primary, assisted primary, and secondary patencies and limb salvage rates for below-knee popliteal bypasses were 83.5%, 89.5%, 94.7%, and 94.4%, respectively. Primary, assisted primary, and secondary patencies and limb salvage rates for tibial bypasses were 44.4%, 44.4%, 63.2%, and 74.9%, respectively. Distaflo precuffed graft is a good alternative conduit for below-knee popliteal and tibial lower extremity reconstructions in the absence of an autologous vein and appears to have promising early patency and limb salvage rates even when used for tibial bypasses.
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Affiliation(s)
- Iosif Gulkarov
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Rajesh Malik
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Rakhsim Yakubov
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Paul Gagne
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Bart E. Muhs
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Caron Rockman
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Neal S. Cayne
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Glenn R. Jacobowitz
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Patrick J. Lamparello
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Mark A. Adelman
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York
| | - Thomas S. Maldonado
- Division of Vascular Surgery, Department of Surgery, New York University School of Medicine, New York,
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8
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How TV, Fisher RK, Brennan JA, Harris PL. Swirling flow pattern in a non-planar model of an interposition vein cuff anastomosis. Med Eng Phys 2006; 28:27-35. [PMID: 15921948 DOI: 10.1016/j.medengphy.2005.04.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Accepted: 04/11/2005] [Indexed: 11/23/2022]
Abstract
One of the main causes of long-term failure of ePTFE grafts is the development of anastomotic intimal hyperplasia which leads to graft thrombosis. Experimental studies with bypass grafts have shown an inverse relationship between mean wall shear stress and intimal hyperplasia. The geometry of the anastomosis has a strong influence on the flow pattern and wall shear stress distribution. The aim of this in vitro study was to investigate the influence of non-planarity in a model of a distal anastomosis with interposition vein cuff, an anastomosis configuration that is increasingly being used because of improved clinical results. Laser Doppler anemometer measurements were carried out in silicone rubber models of interposition vein cuff anastomoses with planar and non-planar inflow. The pulsatile flow waveforms were typical of those found in femoro-infrapopliteal bypass. Axial and radial velocities were measured in the proximal and distal outflow segments. As expected a symmetrical helical flow pattern (Dean flow) was evident in the planar model. The model with non-planar inflow, however, gave rise to swirling flow in both the distal and proximal artery outflow segments for during the systolic phase. In patients, the anastomosis is usually non-planar. Since the configuration depends in part upon the tunnelling of the graft, this may be altered to some extent. Non-planar anastomotic configurations induce a swirling flow pattern, which may normalise wall shear stress, thereby potentially reducing intimal hyperplasia.
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Affiliation(s)
- T V How
- Department of Clinical Engineering, University of Liverpool, Liverpool L69 3GA, UK.
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9
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Longest PW, Kleinstreuer C, Deanda A. Numerical Simulation of Wall Shear Stress and Particle-Based Hemodynamic Parameters in Pre-Cuffed and Streamlined End-to-Side Anastomoses. Ann Biomed Eng 2005; 33:1752-66. [PMID: 16389524 DOI: 10.1007/s10439-005-7784-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Accepted: 08/04/2005] [Indexed: 11/28/2022]
Abstract
A number of research studies have related multiple hemodynamic parameters to the formation of distal anastomotic intimal hyperplasia (IH) at the sub-cellular, cellular, and tissue levels. Focusing on mitigating WSS-based parameters alone, several studies have suggested geometrically modified end-to-side anastomoses with the intent of improving synthetic graft patency rates. However, recent clinical trials of commercially available versions of these grafts indicate persistently high rates of failure. Furthermore, recent evidence suggests that platelet-wall interactions may play a significant role in the formation of IH, which is not captured by WSS-based parameters alone. In this study, numerical simulations have been conducted to assess the potential for IH formation in conventional and geometrically modified anastomoses based on both wall shear stress (WSS) conditions and platelet-wall interactions. Sites of significant particle-wall interactions, including elevated concentrations and stasis, were identified by a near-wall residence time model, which includes factors for platelet activation and surface reactivity. Conventional, pre-cuffed, and streamlined distal end-to-side anastomoses were considered with proximal and distal arterial outflow. It was found that a pre-cuffed anastomosis, similar to the Distaflo configuration, does not offer a hemodynamic advantage over the conventional design considered with respect to the magnitude of the WSS field and the potential for platelet interactions with the vessel surface. Streamlined configurations largely consistent with venous confluences resulted in an advantageous reduction of wall shear stress gradient values; however, particle-wall interactions remained significant throughout the anastomosis. Results of this study are not intended to be directly extrapolated to surgical recommendations. However, these results highlight the difficulty associated with designing an end-to-side distal anastomosis with two-way outflow that is capable of simultaneously reducing multiple hemodynamic parameters. Further testing will be necessary to determine if the observed elevated particle-wall interactions in a pre-cuffed anastomosis provide the stimulus responsible for the reported high failure rates of these grafts.
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Affiliation(s)
- P Worth Longest
- Department of Mechanical Engineering, Virginia Commonwealth University, Richmond, VA, 23284-3015, USA.
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10
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Brien TO, Walsh M, McGloughlin T. On reducing abnormal hemodynamics in the femoral end-to-side anastomosis: the influence of mechanical factors. Ann Biomed Eng 2005; 33:310-22. [PMID: 15868721 DOI: 10.1007/s10439-005-1733-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study was concerned with investigating the influence of mechanical factors on the hemodynamics of the end-to-side anastomosis in an attempt to identify critical factors and establish if it is possible to re-engineer existing, patient-specific, by-pass grafts with a view to increasing their patency. The study chose the femoral artery as the principal subject of interest. Wall shear stresses (WSS) and wall shear stress gradients (WSSG) were taken as the primary quantities of interest. Angle, graft calibre, interposition cuffs, proximal outflow and inlet waveform were studied. The study found that the use of cuffs and patches can significantly reduce abnormal WSS and WSSG by up to 70% when compared to a benchmark 45 degrees conventional anastomosis. The Taylor patch was found to be more robust in reducing peak WSS magnitudes and gradients than the Miller cuff, where design variables proved to be more critical. On the addition of a Taylor patch to a realistic end-to-side femoral anastomosis, the peak WSS and WSSG were found to be reduced by 27% and 57%, respectively. In conclusion, it is possible to use idealised models to identify critical disease influencing factors and to use these findings to reduce the effects of abnormal hemodynamics in realistic, patient-dependant models.
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Affiliation(s)
- Thomas O Brien
- Centre for Applied Biomedical Engineering Research, Department of Mechanical and Aeronautical Engineering, University of Limerick, Limerick, Ireland.
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11
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Heise M, Schmidt S, Krüger U, Rückert R, Rösler S, Neuhaus P, Settmacher U. Flow pattern and shear stress distribution of distal end-to-side anastomoses. A comparison of the instantaneous velocity fields obtained by particle image velocimetry. J Biomech 2004; 37:1043-51. [PMID: 15165874 DOI: 10.1016/j.jbiomech.2003.11.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2003] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To describe the local hemodynamics and pressure losses of crural bypass anastomoses using instantaneous velocity fields acquired by particle image velocimetry (PIV). METHODS Silastic models of a Taylor patch, a Miller cuff and a femoro-crural patch prosthesis (FCPP) were attached to a circuit driven by a Berlin Heart, providing a pulsatile flow with an amplitude of 450 to 25 ml/min (mean 200 ml/min). An outflow resistance of 0.5 mmHg/ml/min (peripheral resistance units, PRU) was modeled using small silastic tubes providing a phase shift of -12 degrees between flow and pressure curves. The working fluid consisted of a glycerine/water mixture with a viscosity of 4 mPas. Hollow glass spheres with a mean size of 9-13 microm were used as tracer particles. Instantaneous velocity fields were obtained by means of PIV and shear rates as well as shear stresses were calculated. Triggered by the flowmeter signal, 10 measurements at 100 ms intervals per cardiac cycle were obtained. The pressures were measured on the inflow and at both distal outflows. The resulting mean pressure losses due to flow separation and distal fluid acceleration were calculated. RESULTS Inside the Taylor patch anastomosis a large flow separation at the hood containing a clockwise rotating vortex was found. Additionally a smaller flow separation at the heel and a flow stagnation zone on the floor of the recipient artery were observed. Conversely, inside the Miller cuff a counterclockwise rotating vortex was seen inside a large heel flow separation. The FCPP also showed typical separation areas at the hood and heel of the anastomosis, although these were smaller compared to the other anastomoses. Inside the FCPP anastomosis no vortex creation was observed throughout the cardiac cycle. The mainstream velocities at the inlet levels were comparable for the three anastomoses. A significant fluid acceleration was present at the antegrade as well as the retrograde outlets of the Taylor and Miller cuff, while the fluid acceleration at the antegrade outflow of the FCPP was small, which was attributed to the end-to-end configuration of the antegrade FCPP leg. The calculated normalized antegrade and retrograde pressure losses for the Taylor form were 0.90 and 0.88, for the Miller cuff 0.89 and 0.86 and for the FCPP 0.94 and 0.86, respectively. The shear stresses inside the flow separations of the three anastomoses were significantly lower than normal wall shear stresses. High shear stress levels were found inside the transition zones between flow separation and high velocity mainstream. CONCLUSIONS The flow pattern inside cuffed or funnel shaped anastomoses consists of large flow separation zones, which are thought to be associated with intimal hyperplasia development. In addition, fluid accelerations at the distal outlets result in pressure losses, which may contribute to impaired crural perfusion.
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Affiliation(s)
- Michael Heise
- Charité, Campus Virchow Klinikum, Department of General Transplantation and Vascular Surgery, Augustenburger Platz 1, Berlin 13353, Germany.
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12
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Ducasse E, Fleurisse L, Vernier G, Speziale F, Fiorani P, Puppinck P, Creusy C. Interposition Vein Cuff and Intimal Hyperplasia: An Experimental Study. Eur J Vasc Endovasc Surg 2004; 27:617-21. [PMID: 15121112 DOI: 10.1016/j.ejvs.2004.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2004] [Indexed: 11/28/2022]
Abstract
OBJECTIVE There is some evidence to suggest that prosthetic distal bypass graft patency can be improved, and the risk of intimal hyperplasia diminished, by interposing a distal vein cuff. We studied intimal remodeling in an end-to-side distal prosthetic anastomosis constructed with and without a vein cuff. METHODS Twenty-four prosthetic bypasses were constructed with (N=12) or without (N=12) a distal vein cuff in 12 pigs. At 10 weeks, the 20 anastomoses and adjacent arteries from the surviving 10 pigs were studied by histology, immunohistochemistry and morphometry. RESULTS Intimal hyperplasia was significantly less on all zones of the arterial floor and all suture zone of arteries anastomosed with a vein cuff than within arteries anastomosed without a vein cuff (0.11 versus 0.34; p=0.001 and 0.35 versus 1.19; p=0.0001, respectively). Intimal hyperplasia was also more prominent within the vein cuff than within the recipient artery, with or without a vein cuff (1.35 versus 0.38; p=0.0001). CONCLUSION An interposition vein cuff at the distal anastomosis between a prosthesis and an artery alters the distribution of intimal hyperplasia. By acting as an expansion chamber where intimal hyperplasia can develop harmlessly, the vein cuff may protect the arterial anastomosis from stenosis.
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Affiliation(s)
- E Ducasse
- Unit of Cytology and Pathological Anatomy, Catholic Institute of Lille, Lille, France
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13
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Ducasse E, Chevalier J, Chevier E, Forzy G, Speziale F, Sbarigia E, Fiorani P, Puppinck P. Patency and Limb Salvage after Distal Prosthetic Bypass Associated with Vein Cuff and Arteriovenous Fistula. Eur J Vasc Endovasc Surg 2004; 27:417-22. [PMID: 15015194 DOI: 10.1016/j.ejvs.2004.01.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2004] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To assess the usefulness of vein cuff with or without arteriovenous fistula interposition as adjuvant techniques for improving patency and limb salvage in patients undergoing femorodistal bypass surgery using prosthetic grafts. METHOD We undertook a retrospective study of 65 consecutive patients treated over a 5-year period with 67 prosthetic femorodistal bypasses with vein cuff, in whom an arteriovenous fistula was constructed at the distal anastomosis in 35. Patients were followed for a median time period of 23 months. RESULTS Primary patency rates were 68, 53 and 44% at 1, 2 and 3 years, respectively. The corresponding figures for secondary patency, limb survival and patients' survival were 73, 64 and 58% for 1 year, 78, 76 and 73% for 2 years and 72, 66 and 63% for 3 years. None of the criteria analyzed influenced patency or limb salvage on prosthetic bypasses using adjuvant techniques. No statistical differences were found between patency and limb salvage rates in patients for whom the vein cuff was constructed with or without an arteriovenous fistula. But patients who managed with a supplementary arteriovenous fistula had significantly fewer distal residual arteries in the limb (p=0.001). CONCLUSION Although results in patients treated with adjunctive techniques differed little from those in patients treated with direct prosthetic bypasses procedures, those who eventually had an adjunctive procedure had inferior runoff. This indicates that an arteriovenous fistula might be a valuable supplement in patients with poor runoff who have distal revascularisation using a prosthetic graft.
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Affiliation(s)
- E Ducasse
- Unit of Vascular Surgery, Catholic Institute of Lille, France.
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14
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Trubel W, Schima H, Czerny M, Perktold K, Schimek MG, Polterauer P. Experimental comparison of four methods of end-to-side anastomosis with expanded polytetrafluoroethylene. Br J Surg 2003; 91:159-67. [PMID: 14760662 DOI: 10.1002/bjs.4388] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background
Four established techniques of distal end-to-side anastomosis (direct anastomosis, Linton patch, Taylor patch and Miller cuff) were compared to investigate the local distribution of anastomotic intimal hyperplasia. The study aimed to elucidate whether mechanical factors or flow alterations are mainly responsible for the improved patency rates reported for vein cuff interposition techniques in infrainguinal arterial reconstructions using prosthetic graft material.
Methods
Thirty-two expanded polytetrafluoroethylene (ePTFE) femoropopliteal bypass grafts were implanted in 16 sheep using the four anastomotic techniques. After 6 months the grafts were explanted and examined histologically. The local distribution of intimal hyperplasia was determined, particularly for areas of material transition and of high and low shear stress.
Results
The mean amount and distribution of intimal hyperplasia were similar for all anastomotic types. Intimal hyperplasia was greatest along all transitions between ePTFE and venous patches, and between ePTFE and recipient artery. It was lower along the transitions between venous patches and artery, and was lowest at the host artery floor.
Conclusion
Vein interposition did not reduce anastomotic intimal hyperplasia and did not change the distribution patterns of hyperplasia, which were influenced mainly by mechanical factors. The effect of vein interposition is to move areas of maximum intimal hyperplasia away from the small recipient artery up to the more capacious graft-patch anastomosis.
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Affiliation(s)
- W Trubel
- Department of Vascular Surgery and Ludwig Boltzmann Institute of Cardiosurgical Research, University of Vienna School of Medicine, Vienna, Austria.
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15
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Fisher RK, Kirkpatrick UJ, How TV, Brennan JA, Gilling-Smith GL, Harris PL. The distaflo graft: a valid alternative to interposition vein? Eur J Vasc Endovasc Surg 2003; 25:235-9. [PMID: 12623335 DOI: 10.1053/ejvs.2002.1840] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
INTRODUCTION the rationale behind the Distaflo graft is inhibition of myointimal hyperplasia through optimisation of haemodynamic forces at the distal anastomosis. This prospective study reports our early clinical results. METHOD patients with critical limb ischaemia, but no autologous vein, underwent infrainguinal bypass using Distaflo. Clinical and Duplex assessment provided prospective data from which one year cumulative patency, limb salvage and survival rates were calculated using Kaplan-Meier analysis. Log rank test enabled comparison with an historical control group of Miller cuff grafts. RESULTS fifty Distaflo were inserted over 29 months into 46 patients, median age 68.5 years, 27 male (59%), of which 27 (54%) were re-do procedures. Proximal anastomoses were to common femoral arteries in 40 cases (80%); distal anastomoses were to popliteal vessels in 20 (40%), and tibial vessels in 30 (60%). The Distaflo graft had patency, limb salvage and survival rates of 39, 50 and 82% respectively compared to 49, 56 and 85% respectively in the control group, with no statistical difference (p = 0.39; 0.65; 0.67 respectively; log rank). CONCLUSION in this non-randomised study, the Distaflo has similar one year patency, limb salvage and survival rates to the Miller cuff, potentially justifying its use an alternative in distal prosthetic arterial reconstruction for critical limb ischaemia.
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Affiliation(s)
- R K Fisher
- Regional Vascular Unit, Royal Liverpool University Hospital, UK
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16
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Cole JS, Watterson JK, O'Reilly MJG. Is there a haemodynamic advantage associated with cuffed arterial anastomoses? J Biomech 2002; 35:1337-46. [PMID: 12231279 DOI: 10.1016/s0021-9290(02)00174-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The development of intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, involving the incorporation of a small section of vein (vein cuff) into the distal anastomosis of PTFE grafts, results in an altered distribution of intimal hyperplasia and improved graft patency rates, especially for below-knee grafts. Numerical simulations have been conducted under physiological conditions to identify the flow behaviour in a typical cuffed bypass model and to determine whether the improved performance of the cuffed system can be accounted for by haemodynamic factors. The flow patterns at the cuffed anastomosis are significantly different to those at the conventional end-to-side anastomosis. In the former case, the flow is characterised by an expansive, low momentum recirculation within the cuff. Separation occurs at the graft heel, and at the cuff toe as the blood enters the recipient artery. Wall shear stresses in the vicinity of the cuff heel are low, but high shear stresses and large spatial gradients in the shearing force act on the artery floor during systole. In contrast, a less disturbed flow prevails and the floor shear stress distribution is less adverse in the conventional model. In conclusion, aspects of the anastomotic haemodynamics are worsened when the cuff is employed. The benefits associated with the cuffed grafts may be related primarily to the presence of venous material at the anastomosis. Therefore, caution is advised with regard to the use of PTFE grafts, pre-shaped to resemble a cuffed geometry.
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Affiliation(s)
- J S Cole
- School of Aeronautical Engineering, The Queen's University of Belfast, BT9 5AG, Belfast, UK.
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17
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Abstract
Anastomotic intimal hyperplasia caused by unphysiological hemodynamics is generally accepted as a reason for dialysis access graft occlusion. Optimizing the venous anastomosis can improve the patency rate of arteriovenous grafts. The purpose of this study was to examine, evaluate, and characterize the local hemodynamics and, in particular, the wall shear stresses in conventional venous end-to-side anastomosis and in patch form anastomosis (Venaflo) by three-dimensional computational fluid dynamics (CFD). We investigated the conventional form of end-to-side anastomosis and a new patch form by numerical simulation of blood flow. The numerical simulation was done with a finite volume-based algorithm. The anastomotic forms were constructed with usual size and fixed walls. Subdividing the flow domain into multiple control volumes solved the fundamental equations. The boundary conditions were identical for both forms. The velocity profile of the patch form is better than that for the conventional form. The region of high static pressure caused by flow stagnation is reduced on the vein floor. The anastomotic wall shear stress is decreased. The results of this study strongly support patch form use to reduce the incidence of intimal hyperplasia and venous anastomotic stenoses.
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Affiliation(s)
- Ulf Krueger
- Deparment of Vascular Surgery, Queen Elisabeth Hospital, Berlin, Germany
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18
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Cole JS, Wijesinghe LD, Watterson JK, Scott DJA. Computational and experimental simulations of the haemodynamics at cuffed arterial bypass graft anastomoses. Proc Inst Mech Eng H 2002; 216:135-43. [PMID: 12022420 DOI: 10.1243/0954411021536351] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The development of intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, involving the incorporation of a small section of vein (vein cuff) into the distal anastomosis of polytetrafluoroethylene (PTFE) grafts, alters the distribution of intimal hyperplasia and improves graft performance. Numerical and in vitro flow visualization experiments have been conducted to identify the flow behaviour in the cuffed bypass model and to determine whether the improved performance of the cuffed system can be accounted for by haemodynamic factors. The flowfield at the cuffed anastomosis is characterized by an expansive recirculation. Separation occurs at the graft heel, and at the cuff toe as the blood enters the recipient artery. Wall shear stresses in the vicinity of the cuff heel are low, but high shear stresses and large spatial gradients in the shearing force act for a time on the artery floor. In the conventional model, a less disturbed flow prevails while the gradients of shear stress on the floor are smaller. Aspects of the anastomotic haemodynamics are worsened when the cuff is employed. The superior patency rates of cuffed bypasses may not be explained purely on the basis of local haemodynamic factors.
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Affiliation(s)
- J S Cole
- School of Aeronautical Engineering, The Queen's University of Belfast, Northern Ireland, UK
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19
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Fisher RK, How TV, Toonder IM, Hoedt MT, Brennan JA, Gilling-Smith GL, Harris PL. Harnessing haemodynamic forces for the suppression of anastomotic intimal hyperplasia: the rationale for precuffed grafts. Eur J Vasc Endovasc Surg 2001; 21:520-8. [PMID: 11397026 DOI: 10.1053/ejvs.2001.1365] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES Standardisation of cuff geometry by manufacturing prosthetic precuffed grafts (PCG) theoretically optimises haemodynamic forces. This study was designed in order to determine whether these beneficial flow patterns are replicated in vivo in PCG. PATIENTS AND METHODS Flow visualisation and Doppler studies performed on anatomically accurate PCG models characterised in vitro anastomotic flow patterns. Thirty-two patients (median age 68 years) in whom autologous vein was unavailable, underwent bypass using PCG. Post-operative analysis included qualitative assessment of flow within the distal anastomosis using Doppler colour flow mapping. Cardiac gating techniques and assessment of velocity distribution were performed to gain additional information. These in vivo results were validated against the bench studies. RESULTS A cohesive vortex was identified within the distal anastomosis of in vitro models and had an integral relationship with the cardiac cycle. This flow structure was also characterised using Doppler colour flow mapping in both longitudinal and transverse planes, confirming the location of the vortex within the body and proximal part of the anastomosis. Twenty-two patients (69%) undergoing bypass with a PCG underwent successful Doppler assessment one week post-operatively, of whom 17 (77%) had a vortical flow structure identified at the distal anastomosis, similar to that characterised in vitro. Cardiac gating verified the same integral relationship of the vortex with the cardiac cycle as that described in vitro. CONCLUSION The geometric configuration of precuffed grafts induced vortices within the distal anastomoses in 17 out of 22 patients undergoing arterial reconstruction, thereby harnessing the haemodynamic forces that may suppress anastomotic hyperplasia and improve patency rates.
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Affiliation(s)
- R K Fisher
- Department of Clinical Engineering, The Royal Liverpool University Hospital, UK
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20
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Piorko D, Knez P, Nelson K, Schmitz-Rixen T. Compliance in Anastomoses With and Without Vein Cuff Interposition. Eur J Vasc Endovasc Surg 2001; 21:461-6. [PMID: 11352524 DOI: 10.1053/ejvs.2001.1353] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE to compare anastomotic compliance in end-to-side anastomoses with and without vein cuff interposition. Materials polytetrafluoroethylene graft to bovine carotid artery without (standard) and with vein interposition (Linton-patch and Miller-cuff). METHODS zonewise compliance measurement of end-to-side anastomoses in an in-vitro circulation system. The zone most distal to the suture-line served as reference compliance. RESULTS directly distal to the suture-line the compliance of the Linton-patch (5.6+/-1.6%/100 mmHg) and Miller-cuff anastomosis (5.2+/-1.1%/100 mmHg) more closely approached reference compliance (standard: 5.0+/-1.2, Linton-patch: 4.5+/-1.5, Miller-cuff: 4.9+/-1.0%/100 mmHg) than that of the standard anastomosis (7.9+/-3.0%/100 mmHg). The maximal compliance values of the Linton-patch (9.5+/-2.3%/100 mmHg) and Miller-cuff anastomoses (9.8+/-2.7%/100 mmHg) were significantly higher than that of the standard end-to-side anastomosis (7.9+/-3.0%/100 mmHg). However, maximal compliance was shifted from the zone directly distal to the suture line in the standard end-to-side anastomosis, to the vein cuff interposition in the Linton-patch and Miller-cuff anastomoses. CONCLUSION the shift in maximal compliance to the wider portion of the anastomosis in the Miller-cuff and Linton-patch anastomoses may obviate reocclusion.
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Affiliation(s)
- D Piorko
- Department of Vascular and Endovascular Surgery, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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21
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Fisher RK, How TV, Carpenter T, Brennan JA, Harris PL. Optimising Miller Cuff Dimensions. The Influence of Geometry on Anastomotic Flow Patterns. Eur J Vasc Endovasc Surg 2001; 21:251-60. [PMID: 11352685 DOI: 10.1053/ejvs.2000.1273] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES since cuff dimensions are variable, we studied the influence of cuff geometry on flow mechanics, in an attempt to identify the optimum configuration. MATERIALS AND METHODS bench studies involved the manufacture of anatomically accurate models of varying cuff dimensions, perfused in a specifically designed flow rig, simulating physiological conditions. Flow visualisation studies incorporating laser illumination of tracer particles enabled accurate analysis of flow patterns. RESULTS the vortex created within the proximal cuff of each model during the deceleration phase of the cardiac cycle was strongly influenced by the aspect ratio (AR=cuff height:length). The standard and high cuffs (AR=1.63 and 1.18, respectively) demonstrated cohesive vortices and stable flow patterns. Low and long cuffs (AR=2.6 and 2.25, respectively) created more complex vortices with large areas of flow separation and low velocities. CONCLUSIONS aspect ratio has an important influence on flow within the distal anastomosis, with cuff dimensions of 13 mm long and 8-11 mm high (standard and high cuffs) creating beneficial flow patterns anticipated to optimise wall shear stress and inhibit myointimal hyperplasia.
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Affiliation(s)
- R K Fisher
- Regional Vascular Unit and Department of Clinical Engineering, Royal Liverpool University Hospital, Daulby Street, Liverpool L69 3GA, U.K
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22
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Salacinski HJ, Goldner S, Giudiceandrea A, Hamilton G, Seifalian AM, Edwards A, Carson RJ. The mechanical behavior of vascular grafts: a review. J Biomater Appl 2001; 15:241-78. [PMID: 11261602 DOI: 10.1106/na5t-j57a-jtdd-fd04] [Citation(s) in RCA: 290] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The development of intimal hyperplasia (IH) near the anastomosis of a vascular graft to artery is directly related to changes in the wall shear rate distribution. Mismatch in compliance and diameter at the end-to-end anastomosis of a compliant artery and rigid graft cause shear rate disturbances that may induce intimal hyperplasia and ultimately graft failure. The principal strategy being developed to prevent IH is based on the design and fabrication of compliant synthetic or innovative tissue-engineered grafts with viscoelastic properties that mirror those of the human artery. The goal of this review is to discuss how mechanical properties including compliance mismatch, diameter mismatch, Young's modulus and impedance phase angle affect graft failure due to intimal hyperplasia.
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Affiliation(s)
- H J Salacinski
- University Department of Surgery, Royal Free and University College Medical School, University College London and The Royal Free Hospital, UK.
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23
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Lemson MS, Tordoir JH, van Det RJ, Welten RJ, Burger H, Estourgie RJ, Stroecken HJ, Leunissen KM. Effects of a venous cuff at the venous anastomosis of polytetrafluoroethylene grafts for hemodialysis vascular access. J Vasc Surg 2000; 32:1155-63. [PMID: 11107088 DOI: 10.1067/mva.2000.109206] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION AND METHODS The most frequent complication of polytetrafluoroethylene (PTFE) arteriovenous grafts for hemodialysis is thrombotic occlusion due to stenosis caused by intimal hyperplasia. This complication is also known for peripheral bypass grafts. Because the use of a venous cuff at the distal anastomosis improves the patency of peripheral bypass grafts, we considered that it might also improve the patency of PTFE arteriovenous grafts. Therefore, a randomized multicenter trial was carried out to study the effect of a venous cuff at the venous anastomosis of PTFE arteriovenous grafts on the development of stenoses and the patency rates. RESULTS Of the 120 included patients, 59 were randomized for a venous cuff. The incidence of thrombotic occlusion was lower in the cuff group (0.68 per patient-year) than in the no-cuff group (0. 88 per patient-year; P =.0007). However, the primary and secondary patency rates were comparable. The cuff group tended to have fewer stenoses at the venous and arterial anastomoses when examined with duplex scan. Graft failure was higher in patients with an initial anastomosing vein diameter smaller than 4 mm (7 of 18 [39%]) than in those with a vein diameter of 4 mm or larger (16 of 88 [18%]; P =. 052). Local edema, skin atrophy, and obesity yielded a higher risk on graft failure (23% vs 11%). CONCLUSION A venous cuff at the venous anastomosis of PTFE arteriovenous grafts for hemodialysis reduced the incidence of thrombotic occlusions; stenosis at the venous anastomosis was reduced. However, this did not result in a better patency rate. Therefore, the venous cuff should not be used routinely. Initial vein diameter and local problems (edema, obesity, or skin atrophy) appear to be the most important risk factors for graft failure.
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Affiliation(s)
- M S Lemson
- Department of Surgery at the University Hospital, Maastricht, The Netherlands
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24
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Comparison of Two Different Arteriovenous Anastomotic Forms By Numerical 3D Simulation of Blood Flow. Int J Angiol 2000; 9:226-231. [PMID: 11062312 DOI: 10.1007/bf01623899] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Anastomotic intimal hyperplasia caused by unphysiological hemodynamics is generally accepted as a reason for dialysis access graft occlusion. Optimizing the venous anastomosis can improve the patency rate of arteriovenous grafts. The purpose of this study was to examine, evaluate and characterize the local hemodynamics, and in particular, wall shear stresses in conventional venous end-to-side anastomosis and in patch form anastomosis (Venaflotrade mark) by Computational Fluid Dynamics (CFD). The flow simulations were carried out as three-dimensional to extend results of our previous 2D studies. The numerical simulation was done with a finite volume-based algorithm. The anastomotic forms were constructed with usual size and fixed walls. Subdividing the flow domain into multiple control volumes solved the fundamental equations. The boundary conditions were constant for both forms. The velocity profile of the patch form is better than for the conventional form. The region of high static pressure caused on flow stagnation is reduced on the vein floor. The anastomotic wall shear stress is decreased. The results of this study strongly support patch form use to reduce the incidence of intimal hyperplasia and venous anastomotic stenoses.
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25
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Rückert RI, Settmacher U, Krüger U, Scholz H. Femorodistal PTFE bypass grafting for severe limb ischaemia: results of a prospective clinical study using a new distal anastomotic technique. Eur J Vasc Endovasc Surg 2000; 20:51-6. [PMID: 10906298 DOI: 10.1053/ejvs.2000.1119] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES To analyse graft patency and limb salvage following femorodistal bypass with ePTFE using a new distal anastomotic technique. Design prospective non-randomised study. MATERIAL AND METHODS One hundred and twenty-nine patients (M:F; 2.23:1; mean age 65.2+/-10.0 years) underwent 135 operations for severe limb ischaemia. The new anastomosis, constructed entirely from ePTFE, was attached to the popliteal (21), anterior (46) and posterior (52) tibial, and peroneal (16) arteries. Cumulative primary (PPR) and secondary patency rates (SPR), limb salvage and survival were analysed using the Kaplan-Meier method. RESULTS Median follow-up was 45 (range 6 to 72) months. There was no perioperative mortality. PPR and SPR at 1, 2, 3, 4, and 5 years were 63.0%, 44.9%, 35.7%, 33.1% and 27.6% and 74.5%, 55.2%, 44.8%, 43.0%, and 37.6%, respectively. Cumulative limb salvage was 86.4%, 78.7%, and 73.2% at 1, 3, and 5 years, respectively. CONCLUSIONS This new anastomotic design was feasible and resulted in acceptable long-term results.
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Affiliation(s)
- R I Rückert
- Department of Surgery, Humboldt University Medical School (Charité), Berlin, Germany
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26
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How TV, Rowe CS, Gilling-Smith GL, Harris PL. Interposition vein cuff anastomosis alters wall shear stress distribution in the recipient artery. J Vasc Surg 2000; 31:1008-17. [PMID: 10805893 DOI: 10.1067/mva.2000.105961] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Interposition of a vein cuff between a prosthetic infrainguinal bypass graft and a recipient infrageniculate artery can improve graft patency. There is evidence that the improved performance may be explained by a redistribution of myointimal hyperplasia (MIH) away from the critical areas at the heel and toe of the cuff-artery anastomosis. It is widely accepted that there is an association between hemodynamic forces, more specifically, low wall shear stress (WSS), and the development of MIH. The aim of this study was to determine whether the reported redistribution of MIH in the interposition vein cuff (IVC) may be explained by differences in magnitude and distribution of WSS. Design of Study and Method: Detailed flow velocity measurements were made in life-size models of conventional end-to-side (ETS) and IVC anastomoses using a two-component laser Doppler anemometer under pulsatile flow conditions. Velocity vectors were determined in the plane of symmetry of the anastomosis, and the variation of WSS was estimated from near-wall velocity measurements on the floor and upper wall of the artery. RESULTS The main flow features in the ETS anastomosis were flow separation at the graft hood, strong radial velocity at the heel, and a stagnation point on the floor of the artery that moved slightly during the flow cycle. In the IVC anastomosis, a coherent vortex that occupied most of the cuff volume was present from the systolic deceleration phase to end diastole. A stagnation point on the anastomosis floor was found to oscillate by about 4 mm. Critical regions of low mean WSS (ie, below 0.5 N/m(2)) were identified. In the ETS anastomosis, they were found at the heel and along the floor. In the IVC anastomosis, low mean WSS was found only on the floor, and it was generally less extensive than in the ETS anastomosis. CONCLUSION The vein cuff anastomosis alters the mean WSS distribution within the recipient artery and removes the area of low WSS at the heel. This may explain the redistribution of MIH away from important sites in the recipient artery.
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Affiliation(s)
- T V How
- Department of Clinical Engineering, University of Liverpool, Regional Vascular Unit, Royal Liverpool University Hospital, United Kingdom
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27
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Lemson MS, Tordoir JH, Daemen MJ, Kitslaar PJ. Intimal hyperplasia in vascular grafts. Eur J Vasc Endovasc Surg 2000; 19:336-50. [PMID: 10801366 DOI: 10.1053/ejvs.1999.1040] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- M S Lemson
- Department of Surgery, University Hospital Maastricht, The Netherlands
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28
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Sherwin SJ, Shah O, Doorly DJ, Peiró J, Papaharilaou Y, Watkins N, Caro CG, Dumoulin CL. The influence of out-of-plane geometry on the flow within a distal end-to-side anastomosis. J Biomech Eng 2000; 122:86-95. [PMID: 10790834 DOI: 10.1115/1.429630] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This paper describes a computational and experimental investigation of flow in a proto-type model geometry of a fully occluded 45 deg distal end-to-side anastomosis. Previous investigations have considered a similar configuration where the centerlines of the bypass and host vessels lie within a plane, thereby producing a plane of symmetry within the flow. We have extended these investigations by deforming the bypass vessel out of the plane of symmetry, thereby breaking the symmetry of the flow and producing a nonplanar geometry. Experimental data were obtained using magnetic resonance imaging of flow within perspex models and computational data were obtained from simulations using a high-order spectral/hp element method. We found that the nonplanar three-dimensional flow notably alters the distribution of wall shear stress at the bed of the anastomosis, reducing the peak wall shear stress peak by approximately 10 percent when compared with the planar model. Furthermore, an increase in the absolute flux of velocity into the occluded region, proximal to the anastomosis, of 80 percent was observed in the nonplanar geometry when compared with the planar geometry.
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Affiliation(s)
- S J Sherwin
- Aeronautics Department, Imperial College, London, United Kingdom
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29
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Kissin M, Kansal N, Pappas PJ, DeFouw DO, Durán WN, Hobson RW. Vein interposition cuffs decrease the intimal hyperplastic response of polytetrafluoroethylene bypass grafts. J Vasc Surg 2000; 31:69-83. [PMID: 10642710 DOI: 10.1016/s0741-5214(00)70069-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE The modification of the distal anastomosis of polytetrafluoroethylene (PTFE) bypass grafts with vein interposition cuffs (VCs) has been reported to increase graft patency. However, the mechanisms that are responsible for this improved patency are unclear. Because intimal hyperplasia (IH) is a primary cause of prosthetic graft failure, we hypothesized that VCs affect the distal anastomosis by decreasing the IH response of the outflow artery. METHODS Twenty-three female domestic Yorkshire pigs (mean weight, 35 kg) underwent 42 femoral PTFE bypass grafting procedures. The PTFE bypass grafts were separated into the following three groups according to distal anastomotic configuration: end-to-side anastomoses (ES), VCs, and cuffs constructed with PTFE (PCs). Four femoral arteries from two pigs served as healthy controls. At sacrifice, the grafts were perfusion fixed, and the distal anastomoses harvested at 1 and 4 weeks. The specimens were hemisected and serially sectioned to identify the heel, toe, and mid-anastomotic regions. The sections were cut into 5-microm segments and analyzed for intima and media thickness and area, intima/media area ratio, and the distribution of IH in the vein cuff. The roles of transforming growth factor-beta1 and platelet-derived growth factor-BB in IH development were assessed with immunohistochemistry. RESULTS IH development was significantly lower at all areas of the anastomosis, with VCs compared with ES and PCs at 4 weeks (P </=.001). IH decreased in VCs from 1 to 4 weeks in all areas of the anastomosis (P </=.001). PCs showed pronounced IH at the mid-anastomosis as compared with VCs and ES (P </=.001). IH was most pronounced at the toe with ES and PCs (P </=.001). Qualitatively, VCs altered the site of IH development, sparing the recipient artery with preferential thickening of the vein cuff and formation of a pseudointima at the vein-PTFE interface. Immunohistochemistry results showed positive staining for transforming growth factor-beta1, platelet-derived growth factor-BB, and smooth muscle alpha-actin in the hyperplastic intima. CONCLUSION PTFE bypass grafts with VCs had less IH develop than did grafts with ES and PC anastomoses. IH regression in VCs at 4 weeks suggests compensatory vessel wall remodeling mediated by the presence of the VC. Furthermore, VCs caused a redistribution of hyperplasia to the vein-PTFE interface, delaying IH-induced outflow obstruction in the recipient artery. The marked increase in IH with PCs, despite a similar geometric configuration to VCs, suggests that the biologic properties of autogenous tissue dissipate IH development. Similarly, the flow patterns in PCs and VCs should be identical, which suggests a less important role of hemodynamic forces in VC-mediated protection.
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Affiliation(s)
- M Kissin
- Division of Vascular Surgery and Program in Vascular Biology, Department of Surgery, UMDNJ-New Jersey Medical School, Newark, NJ 07103-2714, USA
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30
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Rowe CS, Carpenter TK, How TV, Harris PL. Local haemodynamics of arterial bypass graft anastomoses. Proc Inst Mech Eng H 1999; 213:401-9. [PMID: 10581967 DOI: 10.1243/0954411991535013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
One of the main causes of failure of expanded polytetrafluoroethylene (PTFE) bypass grafts used in the lower limbs is the development of myointimal hyperplasia (MIH). Clinical studies show that higher patency rates can be obtained with the use of an autologous vein cuff (the Miller cuff) interposed between the graft and artery. The reasons for the improved performance are still unclear, but preliminary studies suggest that the change in local haemodynamics due to the cuff geometry may be the significant factor rather than the presence of autologous material. If this is the case, then PTFE grafts can be produced with an integral cuff, i.e. a precuffed graft, with similar haemodynamic patterns to that of the Miller cuff. In this paper, two different types of precuffed graft are presented and their flow patterns are compared with those recorded in the Miller cuff and the conventional end-to-side anastomosis. The haemodynamic studies were carried out using optically clear silicone rubber models under simulated in vivo pulsatile flow conditions. Flow structures similar to those observed in the Miller cuff were seen in the precuffed grafts.
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Affiliation(s)
- C S Rowe
- Department of Clinical Engineering, University of Liverpool, UK
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31
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Wijesinghe LD, Mahmood T, Scott DJ. Axial flow fields in cuffed end-to-side anastomoses: effect of angle and disease progression. Eur J Vasc Endovasc Surg 1999; 18:240-4. [PMID: 10479631 DOI: 10.1053/ejvs.1999.0834] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE to visualise the axial flow fields in standard and cuffed end-to-side anastomoses (ESA). DESIGN in vitro experiments using a flow rig, custom-built glass models and frame-by-frame video analysis of flow patterns in standard and cuffed ESA. SUBJECTS glass models of standard or cuffed (1 cm or 2 cm high) ESA of angles 15, 30, 45 and 60 degrees. RESULTS the cross-sectional area of standard ESA is much smaller than that of ESA between graft and cuff. The size of the vortex in the anastomotic zone of both standard and cuffed ESA increased with increasing ESA angle and cuff height, but did not change with flow rate. The presence of the vortex maintains a zone of flow separation and low shear at the heel of standard and graft/cuff anastomoses. CONCLUSIONS the observations explain the clinical findings of intimal hyperplasia (IH) at the heel of PTFE/cuff anastomoses. The improved patency rates of cuffed ESA may be due not to decreased IH, but to an increased ability of the cuff to accommodate IH before causing a significant stenosis.
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Affiliation(s)
- L D Wijesinghe
- Department of Vascular and Endovascular Surgery, St James's University Hospital, Leeds, U.K
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32
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Noori N, Scherer R, Perktold K, Czerny M, Karner G, Trubel M, Polterauer P, Schima H. Blood flow in distal end-to-side anastomoses with PTFE and a venous patch: results of an in vitro flow visualisation study. Eur J Vasc Endovasc Surg 1999; 18:191-200. [PMID: 10479625 DOI: 10.1053/ejvs.1998.0802] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES non-physiological flow behaviour plays a significant role in the development of distal anastomotic intimal hyperplasia. To investigate flow patterns in four anastomotic types of femoral end-to-side distal bypass graft anastomoses, a flow visualisation study was performed. METHODS transparent 1:1 casted replicas of distal vascular graft anastomoses created by conventional technique, Miller-cuff, Taylor- and Linton-patch were fabricated. A pulsatile mock circulation with a high-speed video system was constructed. Flow pattern was determined at mean Reynolds numbers 100-500. Migrations of the stagnation points on the bottom of the anastomoses at mean Reynolds numbers 100, 230, and 350 were measured. RESULTS a vortex forms during early systole and increases to maximum systole in all anastomoses. During the diastolic phase the vortex moves in the Miller-cuff distally to the toe of the anastomosis and remains standing, while in the other anastomotic types the vortex moves proximally to the heal of the junction and breaks down. The shift of the stagnation point in the Miller-cuff was considerably smaller than in the other anastomoses. CONCLUSION conventional, Linton and Taylor anastomoses show similar flow patterns. The Miller-cuff with its wider cavity shows lower shift of the bottom stagnation point, but a persistent washout of the anastomotic cavity, which may contribute to its reported good clinical performance.
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Affiliation(s)
- N Noori
- Department of Vascular Surgery, LBI of Cardiosurgical Research, Austria
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