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Szafron JM, Heng EE, Boyd J, Humphrey JD, Marsden AL. Hemodynamics and Wall Mechanics of Vascular Graft Failure. Arterioscler Thromb Vasc Biol 2024; 44:1065-1085. [PMID: 38572650 PMCID: PMC11043008 DOI: 10.1161/atvbaha.123.318239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 03/12/2024] [Indexed: 04/05/2024]
Abstract
Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.
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Affiliation(s)
- Jason M Szafron
- Departments of Pediatrics (J.M.S., A.L.M.), Stanford University, CA
| | - Elbert E Heng
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jack Boyd
- Cardiothoracic Surgery (E.E.H., J.B.), Stanford University, CA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT (J.D.H.)
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2
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Ban E, Humphrey JD. New Computational Approach to Shunt Design in Congenital Heart Palliation. J Biomech 2023; 152:111568. [PMID: 37099931 DOI: 10.1016/j.jbiomech.2023.111568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 02/06/2023] [Accepted: 03/23/2023] [Indexed: 03/30/2023]
Abstract
Shunts are commonly used to redirect blood to pulmonary arteries in procedures that palliate congenital cardiovascular defects. Previous clinical studies and hemodynamic simulations reveal a critical role of shunt diameter in balancing flow to pulmonary versus systemic vessels, but the biomechanical process of creating the requisite anastomosis between the shunt and host vessel has received little attention. Here, we report a new Lagrange multiplier-based finite element approach that represents the shunt and host vessels as individual structures and predicts the anastomosis geometry and attachment force that result when the shunt is sutured at an incision in the host, followed by pressurization. Simulations suggest that anastomosis orifice opening increases markedly with increasing length of the host incision and moderately with increasing blood pressure. The host artery is further predicted to conform to common stiff synthetic shunts, whereas more compliant umbilical vessel shunts should conform to the host, with orifice area transitioning between these two extremes via a Hill-type function of shunt stiffness. Moreover, a direct relationship is expected between attachment forces and shunt stiffness. This new computational approach promises to aid in surgical planning for diverse vascular shunts by predicting in vivo pressurized geometries.
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Affiliation(s)
- E Ban
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - J D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA.
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Chong H, Lou J, Bogie KM, Zorman CA, Majerus SJA. Vascular Pressure-Flow Measurement Using CB-PDMS Flexible Strain Sensor. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:1451-1461. [PMID: 31603827 PMCID: PMC6944770 DOI: 10.1109/tbcas.2019.2946519] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Regular monitoring of blood flow and pressure in vascular reconstructions or grafts would provide early warning of graft failure and improve salvage procedures. Based on biocompatible materials, we have developed a new type of thin, flexible pulsation sensor (FPS) which is wrapped around a graft to monitor blood pressure and flow. The FPS uses carbon black (CB) nanoparticles dispersed in polydimethylsiloxane (PDMS) as a piezoresistive sensor layer, which was encapsulated within structural PDMS layers and connected to stainless steel interconnect leads. Because the FPS is more flexible than natural arteries, veins, and synthetic vascular grafts, it can be wrapped around target conduits at the time of surgery and remain implanted for long-term monitoring. In this study, we analyze strain transduction from a blood vessel and characterize the electrical and mechanical response of CB-PDMS from 0-50% strain. An optimum concentration of 14% CB-PDMS was used to fabricate 300-μm thick FPS devices with elastic modulus under 500 kPa, strain range of over 50%, and gauge factor greater than 5. Sensors were tested in vitro on vascular grafts with flows of 0-1,100 mL/min. In vitro testing showed linear output to pulsatile flows and pressures. Cyclic testing demonstrated robust operation over hundreds of cardiac cycles, with ±2.6 mmHg variation in pressure readout. CB-PDMS composite material showed excellent potential in biologic strain sensing applications where a flexible sensor with large maximum strain range is needed.
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Tamimi EA, Ardila DC, Ensley BD, Kellar RS, Vande Geest J. Computationally optimizing the compliance of multilayered biomimetic tissue engineered vascular grafts. J Biomech Eng 2019; 141:2725826. [PMID: 30778568 DOI: 10.1115/1.4042902] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Indexed: 12/19/2022]
Abstract
Coronary artery bypass grafts used to treat coronary artery disease often fail due to compliance mismatch. In this study, we have developed an experimental/computational approach to fabricate an acellular biomimetic hybrid tissue engineered vascular graft composed of alternating layers of electrospun porcine gelatin/polycaprolactone (PCL) and human tropoelastin/PCL blends with the goal of compliance-matching to rat abdominal aorta, while maintaining specific geometrical constraints. Polymeric blends at three different gelatin:PCL (G:PCL) and tropoelastin:PCL (T:PCL) ratios (80:20, 50:50 and 20:80) were mechanically characterized. The stress-strain data was used to develop predictive models, which were used as part of an optimization scheme that was implemented to determine the ratios of G:PCL and T:PCL and the thickness of the individual layers within a tissue engineered vascular graft that would compliance match a target compliance value. The hypocompliant, isocompliant, and hypercompliant grafts had target compliance values of 0.000256, 0.000568 and 0.000880 mmHg-1, respectively. Experimental validation of the optimization demonstrated that the hypercompliant and isocompliant grafts were not statistically significant from their respective target compliance values (p-value=0.37 and 0.89, respectively). The experimental compliance value of the hypocompliant graft was statistically significant than their target compliance value (p-value=0.047). We have successfully demonstrated a design optimization scheme that can be used to fabricate multilayered and biomimetic vascular grafts with targeted geometry and compliance.
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Affiliation(s)
- Ehab Akram Tamimi
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | - Diana Catalina Ardila
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States
| | | | - Robert S Kellar
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ, 86011; Department of Mechanical Engineering, Northern Arizona University, Flagstaff, AZ, 86011; Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011
| | - Jonathan Vande Geest
- ASME Member, Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States, McGowan Institute for Regenerative Medicine, 300 Technology Drive, Pittsburgh, PA, United State 15219
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Wain RAJ, Gaskell NJ, Fsadni AM, Francis J, Whitty JPM. Finite Element Predictions of Sutured and Coupled Microarterial Anastomoses. ADVANCED BIOMEDICAL ENGINEERING 2019. [DOI: 10.14326/abe.8.63] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Richard AJ Wain
- John Tyndall Institute, School of Engineering, University of Central Lancashire
- School of Medicine and Dentistry, University of Central Lancashire
- Department of Plastic & Reconstructive Surgery, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust
| | - Nicolas J Gaskell
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Andrew M Fsadni
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Jonathan Francis
- John Tyndall Institute, School of Engineering, University of Central Lancashire
| | - Justin PM Whitty
- John Tyndall Institute, School of Engineering, University of Central Lancashire
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Plonek T, Zak M, Rylski B, Berezowski M, Czerny M, Beyersdorf F, Jasinski M, Filipiak J. Wall stress correlates with intimal entry tear localization in Type A aortic dissection†. Interact Cardiovasc Thorac Surg 2018; 27:797-801. [DOI: 10.1093/icvts/ivy158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 04/10/2018] [Indexed: 01/12/2023] Open
Affiliation(s)
- Tomasz Plonek
- Department of Cardiac Surgery, Wroclaw Medical University, Wroclaw, Poland
| | - Malgorzata Zak
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Bartosz Rylski
- Department of Cardiovascular Surgery, Faculty of Medicine, Heart Centre Freiburg University, University of Freiburg, Freiburg, Germany
| | - Mikolaj Berezowski
- Department of Cardiac Surgery, Wroclaw Medical University, Wroclaw, Poland
| | - Martin Czerny
- Department of Cardiovascular Surgery, Faculty of Medicine, Heart Centre Freiburg University, University of Freiburg, Freiburg, Germany
| | - Friedhelm Beyersdorf
- Department of Cardiovascular Surgery, Faculty of Medicine, Heart Centre Freiburg University, University of Freiburg, Freiburg, Germany
| | - Marek Jasinski
- Department of Cardiac Surgery, Wroclaw Medical University, Wroclaw, Poland
| | - Jaroslaw Filipiak
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Science and Technology, Wroclaw, Poland
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Plonek T, Zak M, Burzynska K, Rylski B, Gozdzik A, Kustrzycki W, Beyersdorf F, Jasinski M, Filipiak J. The combined impact of mechanical factors on the wall stress of the human ascending aorta - a finite elements study. BMC Cardiovasc Disord 2017; 17:297. [PMID: 29262774 PMCID: PMC5738844 DOI: 10.1186/s12872-017-0733-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/11/2017] [Indexed: 01/16/2023] Open
Affiliation(s)
- Tomasz Plonek
- Department of Cardiac and Thoracic Surgery, Wroclaw Medical University, Borowska 213, 50-556, Wroclaw, Poland.
| | - Malgorzata Zak
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Karolina Burzynska
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Bartosz Rylski
- Department of Cardio-vascular Surgery, Heart Centre Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anna Gozdzik
- Department of Cardiac and Thoracic Surgery, Wroclaw Medical University, Borowska 213, 50-556, Wroclaw, Poland
| | - Wojciech Kustrzycki
- Department of Cardiac and Thoracic Surgery, Wroclaw Medical University, Borowska 213, 50-556, Wroclaw, Poland
| | - Friedhelm Beyersdorf
- Department of Cardio-vascular Surgery, Heart Centre Freiburg University, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marek Jasinski
- Department of Cardiac and Thoracic Surgery, Wroclaw Medical University, Borowska 213, 50-556, Wroclaw, Poland
| | - Jaroslaw Filipiak
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Science and Technology, Wroclaw, Poland
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Inoue Y, Yokota T, Sekitani T, Kaneko A, Woo T, Kobayashi S, Shibuya T, Tanaka M, Kosukegawa H, Saito I, Isoyama T, Abe Y, Yambe T, Someya T, Sekino M. Antithrombotic Protein Filter Composed of Hybrid Tissue-Fabric Material has a Long Lifetime. Ann Biomed Eng 2017; 45:1352-1364. [PMID: 28054160 DOI: 10.1007/s10439-016-1781-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 12/19/2016] [Indexed: 11/26/2022]
Abstract
There are recent reports of hybrid tissue-fabric materials with good performance-high biocompatibility and high mechanical strength. In this study, we demonstrate the capability of a hybrid material as a long-term filter for blood proteins. Polyester fabrics were implanted into rats to fabricate hybrid tissue-fabric material sheets. The hybrid materials comprised biological tissue grown on the fabric. The materials were extracted from the rat's body, approximately 100 days post-implantation. The tissues were decellularized to prevent immunological rejection. An antithrombogenicity test was performed by dropping blood onto the hybrid material surface. The hybrid material showed lesser blood coagulation than polysulfone and cellulose. Blood plasma was filtered using the hybrid material to evaluate the protein removal percentage and the lifetime of the hybrid material in vitro. The hybrid material showed a comparable performance to conventional filters for protein removal. Moreover, the hybrid material could work as a protein filter for 1 month, which is six times the lifetime of polysulfone.
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Affiliation(s)
- Yusuke Inoue
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
- Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
- Department of Medical Engineering and Cardiology, Institute of Development, Aging and Cancer, Tohoku University, Miyagi, 980-8575, Japan
| | - Tomoyuki Yokota
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Tsuyoshi Sekitani
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
- The Institute of Scientific and Industrial Research (ISIR), Osaka University, Osaka, 567-0047, Japan
| | - Akiko Kaneko
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Taeseong Woo
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Shingo Kobayashi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | - Tomokazu Shibuya
- Department of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, 992-8510, Japan
| | - Masaru Tanaka
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Fukuoka, 819-0395, Japan
| | | | - Itsuro Saito
- Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Takashi Isoyama
- Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Yusuke Abe
- Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Tomoyuki Yambe
- Department of Medical Engineering and Cardiology, Institute of Development, Aging and Cancer, Tohoku University, Miyagi, 980-8575, Japan
| | - Takao Someya
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan
| | - Masaki Sekino
- Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo, Tokyo, 113-8656, Japan.
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A computational fluid-structure interaction model to predict the biomechanical properties of the artificial functionally graded aorta. Biosci Rep 2016; 36:BSR20160468. [PMID: 27836981 PMCID: PMC5180251 DOI: 10.1042/bsr20160468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 11/17/2022] Open
Abstract
In the present study, three layers of the ascending aorta in respect to the time and space at various blood pressures have been simulated. Two well-known commercial finite element (FE) software have used to be able to provide a range of reliable numerical results while independent on the software type. The radial displacement compared with the time as well as the peripheral stress and von Mises stress of the aorta have calculated. The aorta model was validated using the differential quadrature method (DQM) solution and, then, in order to design functionally graded materials (FGMs) with different heterogeneous indexes for the artificial vessel, two different materials have been employed. Fluid-structure interaction (FSI) simulation has been carried out on the FGM and a natural vessel of the human body. The heterogeneous index defines the variation of the length in a function. The blood pressure was considered to be a function of both the time and location. Finally, the response characteristics of functionally graded biomaterials (FGBMs) models with different values of heterogeneous material parameters were determined and compared with the behaviour of a natural vessel. The results showed a very good agreement between the numerical findings of the FGM materials and that of the natural vessel. The findings of the present study may have implications not only to understand the performance of different FGMs in bearing the stress and deformation in comparison with the natural human vessels, but also to provide information for the biomaterials expert to be able to select a suitable material as an implant for the aorta.
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A new model for the artificial aorta blood vessels using double-sided radial functionally graded biomaterials. Med Biol Eng Comput 2016; 55:859-871. [PMID: 27629551 DOI: 10.1007/s11517-016-1569-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/02/2016] [Indexed: 10/21/2022]
Abstract
Based on radial functionally graded biomaterials and inspired by the geometry of a real aorta blood vessel, a new model was proposed to fabricate the artificial blood vessels. A finite element analyzer is employed to reach the optimal and proper material properties while earlier, it was validated by two famous theories, i.e., the first shear deformation and the plane elasticity. First, the geometry of a real ascending aorta part was simulated and then solved under the axially varying blood pressure and other real and actual conditions. Since the construction of artificial blood vessels just similar to the natural one is impossible, it was tried to find the best substitutes for other materials. Due to the significant properties of functionally graded biomaterials in the reduction in sudden changes of stress and deformation, these types of materials were selected and studied. Two types of conventional single-sided and an efficient double-sided radial functionally graded vessel were proposed and simulated. The elastic behaviors of proposed vessels were obtained and compared to ones previously attained from the real vessel. The results show that all the desired behaviors cannot be achieved by using a conventional single-sided radial FG vessel. Instead and as a conjecture, a smart double-sided radial FG biomaterial is suggested. Fortunately, the proposed material can meet all the desired goals and satisfy all of the indices simultaneously.
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11
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Modelling and simulation of the mechanical response of a Dacron graft in the pressurization test and an end-to-end anastomosis. J Mech Behav Biomed Mater 2016; 61:36-44. [DOI: 10.1016/j.jmbbm.2016.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 11/22/2022]
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Hoedt M, How T, Poyck P, Wittens C. Why Patencies of Femoropopliteal Bypass Grafts with Distal End-to-End Anastomosis are Comparable with End-to-Side Anastomosis. Ann Thorac Cardiovasc Surg 2015; 21:157-64. [PMID: 25641036 DOI: 10.5761/atcs.oa.14-00121] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE Despite the theoretical favourable hemodynamic advantage of end-to-end anastomosis (ETE), femoropopliteal bypasses with distal ETE and end-to-side anastomosis (ETS) have comparable clinical patencies. We therefore studied the effects of different in vivo anastomotic configurations on hemodynamics in geometrically realistic ETE and ETS in vitro flow models to explain this phenomenon. METHODS Four ETE and two ETS models (30° and 60°) were constructed from in vivo computed tomography angiography data. With flow visualization physiological flow conditions were studied. RESULTS In ETS, a flow separation and recirculation zone was apparent at anastomotic edges with a shifting stagnation point between them during systole. Secondary flow patterns developed with flow deceleration and reversal. Slight out of axis geometry of all ETE resulted in flow separation and recirculation areas comparable to ETS. Vertical flow patterns were more stable in wider and longer bevelled ETE. CONCLUSION Primary flow disturbances in ETE are comparable to ETS and are related to the typical sites where myointimal hyperplasia develops. In ETS, reduction of anastomosis angle will diminish flow disturbances. To reduce flow disturbances in ETE, the creation of a bulbous spatulation with resulting axial displacement of graft in relation to recipient artery should be prevented.
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Affiliation(s)
- Marco Hoedt
- Department of Vascular Surgery, Albert Schweitzer Hospital, Dordrecht, The Netherlands
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13
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Compliance properties of collagen-coated polyethylene terephthalate vascular prostheses. J Appl Biomater Funct Mater 2014; 12:163-71. [PMID: 24756779 DOI: 10.5301/jabfm.5000189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2013] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Compliance mismatch between native artery and a prosthetic graft used for infrainguinal bypass is said to be a factor for graft failure. The aim of this study was to develop a technique for measuring the compliance of collagen-coated polyethylene terephthalate (PET) vascular prostheses and to analyze the influence of several key properties on the elastic behavior of the grafts. METHODS Compliance testing was performed on 3 prostheses with and without internal compliant membrane (ICM). The principle of this test was to study the dimensional changes of prostheses submitted to internal pressure from 30 to 240 mm Hg at intervals of predetermined values. RESULTS We demonstrated that the ICM created links with the inner surface of the crimps and considerably modified the graft behavior when submitted to internal pressure. The results showed that compliance properties were dependent on the wall thickness and the crimping geometry of textile vascular prostheses. Mechanical analysis predicts the circumferential tensile behavior of these arterial grafts and validates tests for measuring compliance.
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14
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Rachev A, Felden L, Ku DN. Design and fabrication of a mechanically matched vascular graft. J Biomech Eng 2012; 133:091004. [PMID: 22010739 DOI: 10.1115/1.4004533] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The study provides a pathway to design a mechanics-matching vascular graft for an end-to-end anastomosis to a host artery. For functional equivalence, we submit that the graft and a host artery should have equal inner deformed diameters, equal pressure-radius module, and experience equal axial forces when subjected to mean arterial pressure. These criteria for mechanical equivalence are valid for a large class of materials that can be considered as elastic incompressible and orthotropic solids. As an example, specific known artery properties were used to design or select a graft made from a new synthetic biomaterial to demonstrate that reliable and robust technology for graft fabrication is possible.
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Affiliation(s)
- Alexander Rachev
- GWW School of Mechanical Engineering, GA Institute of Technology, Atlanta, GA 30332, USA
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15
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Chung J, Li JKJ. Hemodynamic simulation of vascular prosthesis altering pulse wave propagation. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:3678-80. [PMID: 17271091 DOI: 10.1109/iembs.2004.1404033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Potential clinical application of a computer model of the aorta was investigated to study the influence on pulse wave morphology of vascular prosthesis. Ascending aorta, aortic arch and abdominal aorta were replaced with synthetic graft materials and profiles. Geometric and compliance mismatch of the synthetic graft sections replacing part of the natural vessel resulted in alterations of the pulse waveform. These changes in pressure and flow waveforms were compared to investigate their effects on the vascular system for both the uniform and tapered vessel models.
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Affiliation(s)
- J Chung
- Cardiovascular Engineering Lab, Department of Biomedical Engineering, Rutgers University, NJ, USA
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16
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Shalaby S, Chandran K, Burg K. Soft Tissue Replacements. Biomaterials 2007. [DOI: 10.1201/9780849378898.ch8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Zidi M, Cheref M. Mechanical analysis of a prototype of small diameter vascular prosthesis: numerical simulations. Comput Biol Med 2003; 33:65-75. [PMID: 12485630 DOI: 10.1016/s0010-4825(02)00059-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper concerns a mechanical analysis of a prototype of a small diameter vascular prosthesis made of a fibre reinforcement silicone material. The theoretical approach is carried out for a neoHookean strain energy function augmented with unidirectional reinforcing that is characterized by a single additional constitutive parameter for strength of reinforcement. Numerical simulations based on a finite element model compare the compliance of different grafts and predict the degree of the compliance mismatch in an anastomosis between native artery and vascular prosthesis. Furthermore, specific applied strains on the prototype, viewed as arising surgical manipulation and implying telescopic shear have been simulated. Thus, for different fibre reinforcements, the stress gradient through the wall of the tubular structure is evaluated.
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Affiliation(s)
- M Zidi
- Université Paris Val de Marne, Faculté des Sciences et Technologie, Laboratoire de Mécanique Physique/CNRS UMR 7052, 61, avenue du général De Gaulle, 94010 Créteil cédex France.
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Stansby G, Knez P, Berwanger CS, Nelson K, Reichert V, Schmitz-Rixen T. Does vascular stapling improve compliance of vascular anastomoses? VASCULAR SURGERY 2001; 35:115-21. [PMID: 11668379 DOI: 10.1177/153857440103500206] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elastic properties of vessel walls are altered by vascular anastomoses. Such alterations may lead to neointimal hyperplasia, which is a common cause of reocclusion following vascular surgery. The severity of paraanastomotic hypercompliant zones and anastomotic compliance drop depend on suturing material and on elastic properties of the anastomotic vessel segments. This study compares paraanastomotic hypercompliance and anastomotic compliance drop when using a new vascular closure system (VCS) and a conventional, continuous suture line in the preparation of end-to-end anastomoses. Compliance of artery-artery, vein-artery, and polytetrafluoroethylene-artery anastomoses was measured in an artificial circulation system at mean pressures of 60, 90, and 120 mm Hg, comparing conventional suturing and the VCS. When using the VCS for vein-artery anastomoses, significantly less postanastomotic hypercompliance was achieved at mean pressures of 60 mm Hg (14.2 +/-3.8% above remote postanastomotic area), compared to suture (55.1 +/-14.8%, p<0.05). At 90 mm Hg, respective values were 11.0 +/-2.3% for VCS and 54.7 +/-10.1% for suture, p<0.01. At 120 mm Hg, in polytetrafluoroethylene-artery anastomoses, the anastomotic compliance drop was significantly less when using the continuous suture line (93.9 +/-1.1% below remote postanastomotic compliance), compared to VCS (97.2 +/-0.2%, p<0.05). Compared to conventional suturing, use of the VCS reduced postanastomotic hypercompliance in vein-artery anastomoses.
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Affiliation(s)
- G Stansby
- Department of Vascular and Endovascular Surgery, University of Frankfurt am Main, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
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Rachev A, Manoach E, Berry J, Moore JE. A model of stress-induced geometrical remodeling of vessel segments adjacent to stents and artery/graft anastomoses. J Theor Biol 2000; 206:429-43. [PMID: 10988028 DOI: 10.1006/jtbi.2000.2143] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mismatch between the elastic properties and initial geometry of a host artery and an implanted stent or graft cause significant stress concentration at the zones close to junctions. This may contribute to the often observed intimal hyperplasia, resulting in late lumen loss and eventual restenosis. This study proposes a mathematical model for stress-induced thickening of the arterial wall at the zones close to an implanted stent or graft. The host artery was considered initially as a cylindrical shell with constant thickness that was clamped to the stent or graft, which was assumed to be non-deformable in the circumferential direction. It was assumed that the abnormal circumferential and axial stresses due to the bending of the arterial wall cause wall thickening that tends to restore the stress state close to that existing far from the junction. The linear equations of a cylindrical shell with variable thickness were coupled to an evolution equation for the wall thickness. These equations were solved numerically and a parametric study was performed using finite difference method and explicit time step. The results show that the remodeling process is self-limiting and leads to local thickening that gradually decreases with distance from the edge of the stent/graft. Model predictions were tested against morphological findings existing in the literature. Recommendations on stent designs that reduce stress concentrations are discussed.
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Affiliation(s)
- A Rachev
- Bulgarian Academy of Sciences, Institute of Mechanics, Sofia, 1113, Bulgaria.
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21
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van Sambeek MRHM, Hagenaars T, Gussenhoven EJ, Leertouwer TC, van der Lugt A, Hoedt MTC, van Urk H. Vascular Response in the Femoropopliteal Segment After Implantation of an ePTFE Balloon-Expandable Endovascular Graft: An Intravascular Ultrasound Study. J Endovasc Ther 2000. [DOI: 10.1583/1545-1550(2000)007<0204:vritfs>2.3.co;2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Ulrich M, Staalsen N, Djurhuus CB, Christensen TD, Nygaard H, Hasenkam JM. In vivo analysis of dynamic tensile stresses at arterial end-to-end anastomoses. Influence of suture-line and graft on anastomotic biomechanics. Eur J Vasc Endovasc Surg 1999; 18:515-22. [PMID: 10637149 DOI: 10.1053/ejvs.1999.0937] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE to determine the influence of an anastomotic suture line and a graft on dynamic tensile stresses of vascular end-to-end anastomoses in vivo. MATERIAL AND METHODS the abdominal aorta of twelve 35-kg pigs was used as an experimental model. Simultaneous recordings of internal arterial diameter and pressure were performed on each pig at 3 successive stages: (1) The genuine artery (REF), (2) artery-artery (A-A) and (3) graft-artery (G-A) anastomosis at 1-mm increments in the immediate perianastomotic area. Thereby, RD (relative distension), CC (compliance coefficient), E(p)(dynamic pressure-strain elastic modulus) and hysteresis loop areas could be calculated for every measuring point. RESULTS the graft was significantly stiffer than REF. A-A and G-A anastomoses were significantly less compliant than REF. Maximum E(p), minimum CC and hysteresis loop areas were found at the anastomotic line due to minimum anastomotic RD. Downstream of the G-A anastomosis, the RD, CC, E(p)and loop areas were significantly different from REF, but significantly different from A-A. CONCLUSION an animal model for acute studies of mechanical properties of vascular end-to-end anastomoses was developed. The main determinant for anastomotic biomechanics was the suture-line itself.
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Affiliation(s)
- M Ulrich
- Department of Thoracic and Cardiovascular Surgery and Institute of Experimental Clinical Research, Skejby Sygehus, Aarhus University Hospital, Brendstrupgaardsvej, Aarhus N, DK-8200, Denmark
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23
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Kobashi T, Matsuda T. Fabrication of compliant hybrid grafts supported with elastomeric meshes. Cell Transplant 1999; 8:477-88. [PMID: 10580342 DOI: 10.1177/096368979900800503] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We devised tubular hybrid medial tissues with mechanical properties similar to those of native arteries, which were composed of bovine smooth muscle cells (SMCs) and type I collagen with minimal reinforcement with knitted fabric meshes made of synthetic elastomers. Three hybrid medial tissue models that incorporated segmented polyester (mesh A) or polyurethane-nylon (mesh B) meshes were designed: the inner, sandwich, and wrapping models. Hybrid medial tissues were prepared by pouring a cold mixed solution of SMCs and collagen into a tubular glass mold consisting of an inner mandrel and an outer sheath and subsequent thermal gelation, followed by further culture for 7 days. For the inner model, the mandrel was wrapped with a mesh. For the sandwich model, a cylindrically shaped mesh was incorporated into a space between the mandrel and the sheath. The wrapping model was prepared by wrapping a 7-day-incubated nonmesh gel with a mesh. The inner diameter was 3 mm, irrespective of the model, and the length was 2.5-4.0 cm, depending on the model. The intraluminal pressure-external diameter relationship showed that nonmesh and inner models had a very low burst strength below 50 mmHg, while the sandwich model ruptured at around 110-120 mmHg; no rupturing below 240 mmHg was observed for the wrapping model, regardless of the type of mesh used. Compliance values of wrapping and sandwich models were close to those of native arteries. Pressure-dependent distensibility characteristics similar to native arteries were observed for a mesh A wrapping model, whereas a mesh B wrapping model expanded almost linearly as intraluminal pressure increased, which appeared to be due to elasticity of the incorporated mesh. Thus, design criteria for hybrid vascular grafts with appropriate biomechanical matching with host arteries were established. Such hybrid grafts may be mechanically adapted in an arterial system.
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Affiliation(s)
- T Kobashi
- Department of Bioengineering, National Cardiovascular Center Research Institute, Suita, Osaka, Japan
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Thubrikar MJ, Agali P, Robicsek F. Wall stress as a possible mechanism for the development of transverse intimal tears in aortic dissections. J Med Eng Technol 1999; 23:127-34. [PMID: 10561823 DOI: 10.1080/030919099294177] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In aortic dissection intimal tear develops in a transverse direction. Since dissection is associated with the aneurysm of the aorta, its mechanism was investigated by analysing the pressure induced wall stress as a function of 'growth' of the aneurysm. The stresses were determined using a finite element analysis where the aorta was modelled as an isotropic, nonlinear, hyperelastic material. Growth of the aneurysm was simulated by dilating an aortic segment in increments of 10% of the initial diameter. At each dilation luminal pressure of 120 mm Hg was applied and stress determined. In the aneurysm bulb, longitudinal stress increased significantly as the bulb became larger, while circumferential stress changed only a little. In the undilated segment both the longitudinal and circumferential stresses remained relatively unchanged. The increase in the longitudinal stress in the bulb occurred primarily due to change in shape of the aorta from cylindrical to ellipsoidal to spherical. Hence, as the aneurysm 'grows', the longitudinal stress in the bulb increases rapidly and could be responsible for the transverse tear in the aortic dissection.
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Affiliation(s)
- M J Thubrikar
- Heineman Medical Research Laboratory, Carolinas Medical Center, Charlotte, North Carolina, USA
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Doi K, Matsuda T. Significance of porosity and compliance of microporous, polyurethane-based microarterial vessel on neoarterial wall regeneration. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 1997; 37:573-84. [PMID: 9407307 DOI: 10.1002/(sici)1097-4636(19971215)37:4<573::aid-jbm17>3.0.co;2-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The microporous structure of artificial vascular grafts, which increases compliance and porosity simultaneously, may enhance neoarterial regeneration. In order to differentiate these effects, three models of segmented polyurethane grafts (inner diameter, 1.5 mm; wall thickness, 100 microns) with or without micropores fabricated using an excimer laser ablation technique, were prepared, and their neoarterial regenerative potentials were studied upon implantation: Model I (microporous, permeable, compliant); Model II (smooth-surfaced, impermeable, compliant); and Model III (smooth-surfaced, impermeable, noncompliant). In Models I and II, the pore or groove size (diameter, 100 microns) and pore or groove arrangement were fixed, and consequently their compliances were almost identical. Irrespective of model, the luminal surfaces were coated with benzophenone-derivatized gelatin and subsequently photocured. Twenty grafts (length, 20 mm) of each model were implanted in the aortas of rats. Predetermined implantation periods were 4, 12, and 24 weeks. Total patency rate decreased in the order Model I (100%), II (87%), and III (59%) grafts. All patent grafts were completely endothelialized after 12 weeks of implantation, irrespective of model. After 12- and 24-week implantations, in Model I grafts, the neoarterial wall was thin, and smooth muscle cells (SMCs) were of the contractile phenotype. In Model II grafts, the neoarterial wall exhibited considerable thickening. In Model III grafts, the neoarterial wall exhibited marked thickening, and SMCs were of the synthetic phenotype. The neoarterial wall thickness at the midportion of the grafts after 24 weeks of implantation increased in the order Model I (48 +/- 8 microns), II (146 +/- 87 microns), and III (385 +/- 21 microns) grafts. These results strongly suggest that compliance matching and porosity synergistically resulted in neoarterial wall restoration without appreciable thickening.
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Affiliation(s)
- K Doi
- Department of Bioengineering, National Cardiovascular Center Research Institute, Osaka, Japan
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Abstract
Compliance mismatch between a host artery and an implanted graft has been suggested as a contributing factor to a small diameter graft failure. In this study, static compliance and dynamic compliance were defined and measured in vitro and in vivo for canine carotid arteries and 2 types of polyurethane grafts. Based on these compliance values, the circumferential modulus (E[theta]) and longitudinal modulus (Ez) were calculated. It was shown that grafts have constant moduli over a wide range of pressure while the moduli of carotid arteries increase significantly with increasing pressure (dynamic E[theta] from 0.20 to 1.32 MPa). Polyurethane grafts are nearly isotropic, with the modulus almost identical in each direction, while carotid arteries are anisotropic (E[theta]/Ez = 2-3). The dynamic moduli are generally higher than static values and are especially pronounced for arteries. Due to these different inherent characteristics, the compliance of a synthetic graft may match that of the host artery only in the circumferential direction and within a small pressure range. A stated limitation is therefore given for complete compliance matching. The results provide a rationale for identifying the degree of compliance match. These efforts may lead to better designed vascular grafts.
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Affiliation(s)
- S Hsu
- Department of Chemical Engineering, Chung Hsing National University, Taichung, Taiwan, ROC
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Chalmers RT, Hoballah JJ, Sharp WJ, Kresowik TF, Corson JD. Effect of an endovascular stent on healing of an end-to-end polytetrafluoroethylene-artery anastomosis in a canine model. Br J Surg 1994; 81:1443-7. [PMID: 7820465 DOI: 10.1002/bjs.1800811012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A canine model of end-to-end anastomosis between the iliac arteries and polytetrafluoroethylene grafts was developed; a self-expanding Wallstent was placed across one anastomosis. The opposite limb acted as a control. Animals were killed at 4 or 12 weeks. Sections were taken and the intimal thickness and luminal area calculated. At 12 weeks intimal thickness was significantly greater at anastomoses in control sections (P = 0.007), and at the interface between the proximal stent and graft in stented graft limbs (P = 0.01). Control graft limbs had significantly enhanced intimal thickness at the anastomotic level at 12 weeks compared with that at 4 weeks (P = 0.0002), while there was no such increase for the stented side. There was no significant difference in luminal area between control and stented graft limbs. Anastomotic neointimal hyperplasia in a canine graft-artery bypass model is modified by endovascular stenting.
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Affiliation(s)
- R T Chalmers
- Department of Surgery, University of Iowa, Iowa City
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Chalmers RT, Hoballah JJ, Sharp WJ, Kresowik TF, Corson JD. The effect of an intraluminal stent on neointimal hyperplasia at an end-to-side polytetrafluoroethylene graft arterial anastomosis. Am J Surg 1994; 168:85-90. [PMID: 7519832 DOI: 10.1016/s0002-9610(94)80041-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Anastomotic neointimal hyperplasia plays a significant role in the late failure of infrainguinal prosthetic arterial bypass grafts. Previous work from our laboratory revealed that placing a stent across an end-to-end arterio-arterial anastomosis resulted in an increase in the luminal area as well as in the intimal thickness (IT) at the anastomotic level. This study was designed to evaluate the effects on neointimal hyperplasia when a stent is placed across an end-to-side polytetrafluoroethylene (PTFE) graft arterial anastomosis. METHODS A canine model of an end-to-side anastomosis was developed using a 12 x 6 mm polytetrafluoroethylene aortobi-iliac graft. A self-expanding stainless steel Wallstent was placed across one randomly selected distal anastomosis leaving the opposite side as a control. Dogs were sacrificed at 4 and 12 weeks. At sacrifice, the graft and intact anastomoses were pressure-perfusion fixed with glutaraldehyde. Sections of each distal graft, anastomosis, and recipient artery were obtained for analysis. Computer images of each section were digitized to determine the luminal area and the mean IT. The data were analyzed statistically using univariate repeated measures of analysis of variance. RESULTS One animal died prior to early sacrifice. Eight of 10 graft limbs remained patent at sacrifice. Of the 2 limbs that occluded, one was stented and one was nonstented. At 4 weeks, stented graft limbs had significantly greater IT at the proximal stent level (mean difference between control and stented sides 0.163 mm +/- 0.054, P = 0.01). Stented and nonstented anastomoses had similar luminal area and IT at other levels where sections were taken. At 12 weeks, control limbs had significantly greater IT at the anastomotic level compared to the 4-week measurements (mean difference 12 weeks versus 4 weeks 0.185 mm +/- 0.06, P = 0.006). In the stented limbs, IT at the anastomotic level had stabilized and was not significantly thicker than at 4 weeks. The control limbs had greater IT at the anastomotic level than the stented limbs (mean difference between controls and stented sides at 12 weeks 0.091 mm +/- 0.044, P = 0.06). At the proximal end of the stent, IT progressed significantly between the 4th and 12th weeks (mean difference 12 weeks versus 4 weeks 0.155 mm +/- 0.06, P = 0.02). The IT at the proximal end of the stent at 12 weeks was significantly greater than the IT at a comparable level in the controls (mean difference stent versus control 0.132 mm +/- 0.05, P = 0.04). The luminal area in the control limbs was significantly greater than in the stented anastomoses at levels corresponding to either end of the stent (mean difference at proximal end 4.163 mm2 +/- 1.633, P = 0.01; mean difference at distal end 7.192 mm2 +/- 1.633, P = 0.0005). However, there was no difference in luminal area at the anastomotic level. CONCLUSION We conclude that the presence of an intraluminal stent alters the siting and degree of anastomotic neointimal hyperplasia in a canine model of an end-to-side anastomosis resulting in translocation of the intimal hyperplastic response to the proximal graft stent interface in a magnitude similar to that which would normally be found at the anastomosis.
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MESH Headings
- Anastomosis, Surgical/instrumentation
- Anastomosis, Surgical/methods
- Animals
- Aorta, Abdominal/pathology
- Aorta, Abdominal/surgery
- Blood Vessel Prosthesis
- Dogs
- Female
- Graft Occlusion, Vascular/epidemiology
- Graft Occlusion, Vascular/etiology
- Graft Occlusion, Vascular/pathology
- Graft Occlusion, Vascular/prevention & control
- Hyperplasia/pathology
- Iliac Artery/pathology
- Iliac Artery/surgery
- Male
- Materials Testing
- Microscopy, Electron, Scanning
- Models, Biological
- Neovascularization, Pathologic/epidemiology
- Neovascularization, Pathologic/etiology
- Neovascularization, Pathologic/pathology
- Neovascularization, Pathologic/prevention & control
- Polytetrafluoroethylene
- Stents
- Time Factors
- Tunica Intima/pathology
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Affiliation(s)
- R T Chalmers
- Department of Surgery, University of Iowa, Iowa City 52242
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Chandran K, Kim YH. Mechanical aspects of vascular graft-host artery anastomoses. ACTA ACUST UNITED AC 1994. [DOI: 10.1109/51.310993] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Matsumoto T, Itagaki H, Hayashi K. FEM analysis of stress and deformation in the vicinities of arterial graft anastomosis. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/jab.770050110] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Kim YH, Chandran KB, Bower TJ, Corson JD. Flow dynamics across end-to-end vascular bypass graft anastomoses. Ann Biomed Eng 1993; 21:311-20. [PMID: 8214816 DOI: 10.1007/bf02368624] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In this article, a numerical simulation of steady flow across an end-to-end vascular bypass graft anastomosis is presented. In vitro experiments were performed to determine the variations in the conduit cross section at the anastomosis. Penrose surgical drainage tubing was used to simulate an artery and was anastomosed with Polytetrafluoroethylene (PTFE) vascular grafts using a continuous suturing technique. Artery to artery anastomosis was simulated by suturing two Penrose tubing segments. The anastomotic specimens were subject to static transmural pressure in the physiologic range to determine the instantaneous diameter and compliance as a function of the distance from the anastomotic site. The experimentally determined geometries were used to simulate steady flow through an end-to-end anastomosis using the finite analytic (FA) numerical solution technique. The results demonstrated a region of flow separation 2 mm distal to the Penrose tubing-Penrose tubing anastomosis (simulating an artery-artery anastomosis) at higher transmural pressures. Moreover, wall shear stresses increased proximal to the anastomosis in flow from the Penrose tubing to the graft. In flow from the graft to the Penrose tubing, low wall shear stresses were observed distal to the anastomosis. Flow separation was observed distal to the anastomosis at higher transmural pressures with uniform inlet velocity condition. The region of low shear stress in flow from PTFE graft to the Penrose tubing was located nearer to the anastomosis with thin wall grafts than that with standard wall thickness grafts. Our steady flow model studies suggest a correlation between regions of low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia in end-to-end anastomoses.
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Affiliation(s)
- Y H Kim
- Department of Biomedical Engineering, University of Iowa, Iowa City
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