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Liu J, Wang B, Liu W, Hu X, Zhang C, Zhou Z, Lang J, Wu G, Zhang Y, Yang J, Ni Z, Zhao G. Regulating mechanical performance of poly (l-lactide acid) stent by the combined effects of heat and aqueous media. Int J Biol Macromol 2023:124987. [PMID: 37236565 DOI: 10.1016/j.ijbiomac.2023.124987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/08/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023]
Abstract
Annealing process has been applied to the development of thermoforming polymer braided stent and treating its basic constitute monofilaments, especially for Poly (l-lactide acid) (PLLA) condensed by lactic acid monomer made from the plant starch. In this work, high performance monofilaments were produced by melting spun and solid-state drawing methods. Inspired by the effects of water plasticization on semi-crystal polymer, PLLA monofilaments were annealed with and without constraint in vacuum and aqueous media. Then, the co-effects of water infestation and heat on the micro-structure and mechanical properties of these filaments were characterized. Furtherly, mechanical performance of PLLA braided stents shaped by different annealing methods was also compared. Results showed that annealing in aqueous media generated more obvious structure change of PLLA filaments. Interestingly, the combined effects of aqueous phase and thermal effectively increased the crystallinity, and decreased the molecular weight and orientation of PLLA filaments. Therefore, higher modulus, smaller strength, and elongation at the break for filaments could be obtained, which could furtherly realize better radial compression resistance of the braided stent. This annealing strategy could provide new perspectives between anneal and material properties of PLLA monofilaments, and provide more suitable manufacturing technics for polymer braided stent.
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Affiliation(s)
- Jinbo Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Bin Wang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Wentao Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Xue Hu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Chen Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Zhiyuan Zhou
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Ji Lang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing, China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, Nanjing 210044, China
| | - Juekuan Yang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing 211189, China.
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A hazardous boundary of Poly(L-lactic acid) braided stent design: Limited elastic deformability of polymer materials. J Mech Behav Biomed Mater 2023; 138:105628. [PMID: 36543082 DOI: 10.1016/j.jmbbm.2022.105628] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Poly (L-lactic acid) (PLLA) braided stents, which are expected to replace metal stents, are promising in peripheral vascular therapy due to their superior biocompatibility. Although various design ideas have been proposed and investigated on metal stents, few researches are related to the design theory of PLLA braided stent. In this article, mechanical performance of PLLA braided stents with different parameters was systematically evaluated, and a design theory based on material properties was proposed. Different from metal materials, the risk of filament deformation beyond elastic zone should be evaluated and controlled in PLLA stent design. The findings were obtained through combination study of experiments and simulations. Design parameters, including pitch angle and stent diameter, played a crucial role in mechanical performance of PLLA braided stent. The deformation of PLLA stents with larger pitch angles and stent diameters was in elastic zone and thus presented better mechanical performance with satisfactory resilience. This work could provide meaningful suggestions for preparing bioresorbable braided stents with suitable design parameters.
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Tidwell K, Harriet S, Barot V, Bauer A, Vaughan MB, Hossan MR. Design and Analysis of a Biodegradable Polycaprolactone Flow Diverting Stent for Brain Aneurysms. Bioengineering (Basel) 2021; 8:bioengineering8110183. [PMID: 34821749 PMCID: PMC8614946 DOI: 10.3390/bioengineering8110183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/31/2021] [Accepted: 11/09/2021] [Indexed: 11/21/2022] Open
Abstract
The flow diverting stent (FDS) has become a promising endovascular device for the treatment of aneurysms. This research presents a novel biodegradable and non-braided Polycaprolactone (PCL) FDS. The PCL FDS was designed and developed using an in-house fabrication unit and coated on two ends with BaSO4 for angiographic visibility. The mechanical flexibility and quality of FDS surfaces were examined with the UniVert testing machine, scanning electron microscope (SEM), and 3D profilometer. Human umbilical vein endothelial cell (HUVEC) adhesion, proliferation, and cell morphology studies on PCL FDS were performed. The cytotoxicity and NO production by HUVECs with PCL FDS were also conducted. The longitudinal tensile, radial, and bending flexibility were found to be 1.20 ± 0.19 N/mm, 0.56 ± 0.11 N/mm, and 0.34 ± 0.03 N/mm, respectively. The FDS was returned to the original shape and diameter after repeated compression and bending without compromising mechanical integrity. Results also showed that the proliferation and adhesion of HUVECs on the FDS surface increased over time compared to control without FDS. Lactate dehydrogenase (LDH) release and NO production showed that PCL FDS were non-toxic and satisfactory. Cell morphology studies showed that HUVECs were elongated to cover the FD surface and developed an endothelial monolayer. This study is a step forward toward the development and clinical use of biodegradable flow diverting stents for endovascular treatment of the aneurysm.
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Affiliation(s)
- Kaitlyn Tidwell
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Seth Harriet
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Vishal Barot
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
| | - Andrew Bauer
- Department of Neurosurgery, University of Oklahoma-Health Science Center, Oklahoma City, OK 73104, USA;
| | - Melville B. Vaughan
- Department of Biology, University of Central Oklahoma, Edmond, OK 73034, USA;
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
| | - Mohammad R. Hossan
- Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034, USA; (K.T.); (S.H.); (V.B.)
- Center of Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK 73034, USA
- Correspondence: ; Tel.: +1-405-975-5295
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Zhao G, Wang B, Liu M, Tian Y, Wu G, Zhang Y, Cheng J, Ni Z. A study of the radial and bending performance for poly (L‐lactic acid) braided stents with innovative runners. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Bin Wang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Muqing Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Yuan Tian
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering Nanjing Forestry University Nanjing China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School Southeast University Nanjing China
| | - Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
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Wright J, Nguyen A, D’Souza N, Forbess JM, Nugent A, Reddy SRV, Jaquiss R, Welch TR. Bioresorbable Stent to Manage Congenital Heart Defects in Children. MATERIALIA 2021; 16:101078. [PMID: 34109305 PMCID: PMC8184019 DOI: 10.1016/j.mtla.2021.101078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Intravascular stents for pediatric patients that degrade without inhibiting vessel growth remain a clinical challenge. Here, poly(L-lactide) fibers (DH-BDS) at two thicknesses, 250 μm and 300 μm, were assembled into large, pediatric-sized stents (Ø10 - Ø20 mm). Fibers were characterized mechanically and thermally, then stent mechanical properties were compared to metal controls, while mass loss and degradation kinetics modeling estimated total stent degradation time. Thicker fibers displayed lower stiffness (1969 ± 44 vs 2126 ± 37 MPa) and yield stress (117 ± 12 vs 137 ± 5 MPa) than thinner counterparts, but exhibited similar fail strength (478 ± 28 vs 476 ± 16 MPa) at higher strains (47 ± 2 vs 44 ± 2%). Stents all exhibited crystallinity between 51.3 - 54.4% and fiber glass transition temperatures of 88.6 ± 0.5 °C and 84.6 ± 0.5 °C were well above physiological ranges. Radial strength (0.31 ± 0.01 - 0.34 ± 0.02 N/mm) in thinner stents was similar to metal stents (0.24 - 0.41 N/mm) up to Ø14 mm with no foreshortening and thicker coils granted comparable radial strength (0.32 ± 0.02 - 0.34 ± 0.02 N/mm) in stents larger than Ø14 mm. Both 10 mm (1.17 ± 0.02 % and 0.86 ± 0.1 %) and 12 mm (1.1 ± 0.03% and 0.89 ± 0.1%) stents exhibited minimal weight loss over one year. Degradation kinetics models predicted full stent degradation within 2.8 - 4.5 years depending on thickness. DH-BDS exhibiting hoop strength similar to metal stents and demonstrating minimal degradation and strength loss over the first year before completely disappearing within 3 to 4.5 years show promise as a pediatric interventional alternative to current strategies.
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Affiliation(s)
- Jamie Wright
- Department of Cardiovascular Thoracic Surgery, University of Texas at Southwestern Medical Center of Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8879, USA
| | - Annie Nguyen
- Department of Cardiovascular Thoracic Surgery, University of Texas at Southwestern Medical Center of Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8879, USA
| | - Nandika D’Souza
- Department of Material Science, University of North Texas, 1155 Union Circle #310440, Denton, TX 76203-5017
| | - Joseph M. Forbess
- Department of Surgery, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore MD 21201
| | - Alan Nugent
- Department of Pediatrics, Northwestern University, Ann & Robert H. Lurie Children’s Hospital of Chicago Box 21, 225 E Chicago Avenue, Chicago IL 60611, USA
| | - Surendranath R. Veeram Reddy
- Department of Pediatrics, University of Texas at Southwestern Medical Center of DallasAc, 5323 Harry Hines Blvd, Dallas, TX 75390-9063, USA
| | - Robert Jaquiss
- Department of Cardiovascular Thoracic Surgery, University of Texas at Southwestern Medical Center of Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8879, USA
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Li X, Tian Y, Zhang J, Cheng J, Wu G, Zhang Y, Zhao G, Ni Z. Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5266] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Xin Li
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Yuan Tian
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Jing Zhang
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering Nanjing Forestry University Nanjing China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School Southeast University Nanjing China
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
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Tian Y, Liu M, Liu W, Cheng J, Wu G, Han T, Zhang Y, Zhao G, Ni Z. Effects of annealing temperature on both radial supporting performance and axial flexibility of poly(L‐lactic acid) braided stents. J Appl Polym Sci 2021. [DOI: 10.1002/app.50517] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yuan Tian
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Muqing Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Wentao Liu
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Jie Cheng
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Gensheng Wu
- School of Mechanical and Electronic Engineering Nanjing Forestry University Nanjing China
| | - Ting Han
- Department of Thermal Analysis Instrument Mettler‐Toledo Company Shanghai China
| | - Yi Zhang
- Center of Interventional Radiology & Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School Southeast University Nanjing China
| | - Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
| | - Zhonghua Ni
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro‐Nano Biomedical Instruments Southeast University Nanjing China
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Abstract
The quest for an ideal biodegradable stent for both adult coronary and pediatric congenital heart disease applications continues. Over the past few years, a lot of progress has been made toward development of a dedicated pediatric biodegradable stent that can be used for congenital heart disease applications. At present, there are no biodegradable stents available for use in congenital heart disease. In this article, the authors review the different biodegradable materials and their limitations and provide an overview of the current biodegradable stents being evaluated for congenital heart disease applications.
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Affiliation(s)
- Tre R Welch
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Alan W Nugent
- Division of Cardiology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, 225 East Chicago Avenue, Box 21, Chicago, IL 60611, USA
| | - Surendranath R Veeram Reddy
- Division of Cardiology, Department of Pediatrics, University of Texas Southwestern Medical Center, Children's Health System of Texas, Childrens Medical Center, 1935 Medical District Drive, Dallas, TX 75235, USA.
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Zhao F, Xue W, Wang F, Yu C, Xu H, Hao Y, Wang L. A new approach to improve the local compressive properties of PPDO self-expandable stent. J Mech Behav Biomed Mater 2017; 68:318-326. [PMID: 28237687 DOI: 10.1016/j.jmbbm.2017.02.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 02/11/2017] [Accepted: 02/12/2017] [Indexed: 02/07/2023]
Abstract
The radial performance of bioabsorbable polymeric intravascular stents is extremely important in assessing the efficiency of these devices in expanding narrow lumen, reducing stent recoil, and recovering to their original states after suffering from pulsating pressure. However, these stents remain inferior to metallic stents. Several thermal treatment conditions (60°C, 80°C, and 100°C for 1h) were investigated to improve the characteristics of poly(p-dioxanone) (PPDO) self-expandable stents. The local compressive force, stiffness, and viscoelasticity of these stents were also evaluated. Wide-angle X-ray diffraction and different scanning calorimetry measurements were performed to evaluate the recrystalline and thermodynamic changes of molecular chains. The declining conformer entropy of PPDO monofilaments was examined via energy analysis. The untreated stents had compressive modules of 514.80±70.59mN/mm, which was much higher than those of 80°C and 100°C treated stents (332.35±66.08mN/mm and 394.31±64.71mN/mm, respectively). Nevertheless, 100°C annealing stents had less stress relaxation and prior elastic recovery rate of 82.32±3.43mN and 92.55±1.61%, respectively, showing a much better shape stability than untreated stents (139.51±16.67mN and 86.18±3.57%, respectively). These findings present important clinical implications in the stent manufacturing process and warrant further study to develop new bioabsorbable stents with outstanding clinical efficacy.
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Affiliation(s)
- Fan Zhao
- College of Textiles, Donghua University, Shanghai 201620, China; Key Laboratory of Textile Science and Technology of Ministry of Education and College of Textiles, Donghua University, 2999 North Renmin Road, Shanghai 201620, China
| | - Wen Xue
- College of Textiles, Donghua University, Shanghai 201620, China; Key Laboratory of Textile Science and Technology of Ministry of Education and College of Textiles, Donghua University, 2999 North Renmin Road, Shanghai 201620, China
| | - Fujun Wang
- College of Textiles, Donghua University, Shanghai 201620, China; Key Laboratory of Textile Science and Technology of Ministry of Education and College of Textiles, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
| | - Chenglong Yu
- College of Textiles, Donghua University, Shanghai 201620, China
| | - Haiyan Xu
- College of Textiles, Donghua University, Shanghai 201620, China
| | - Yi Hao
- College of Textiles, Donghua University, Shanghai 201620, China
| | - Lu Wang
- College of Textiles, Donghua University, Shanghai 201620, China; Key Laboratory of Textile Science and Technology of Ministry of Education and College of Textiles, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
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Løvdal ALV, Calve S, Yang S, Van Alstine W, Binkert CA, Klausen K. Evaluation of a Bioabsorbable Self-Expandable Vein Stent-Base Made of Poly(l-lactide) In Vitro and In Vivo. Cardiovasc Intervent Radiol 2016; 40:112-119. [DOI: 10.1007/s00270-016-1491-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/26/2016] [Indexed: 11/30/2022]
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Herbert CE, Veeram Reddy S, Welch TR, Wang J, Richardson JA, Forbess JM, Nugent AW. Bench and initial preclinical results of a novel 8 mm diameter double opposed helical biodegradable stent. Catheter Cardiovasc Interv 2016; 88:902-911. [PMID: 27471092 DOI: 10.1002/ccd.26647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/04/2016] [Indexed: 11/05/2022]
Abstract
BACKGROUND Metallic endovascular stents are utilized off-label in congenital heart disease. Biodegradable stents (BDS) offer potential advantages in a growing child. We have previously reported double opposed helical (DH) BDS up to 6 mm diameter (DH-6). The objectives are to investigate the bench characteristics of larger 8 mm diameter BDS (DH-8) manufactured with increasing strut thicknesses and the inflammatory profile in a porcine model. METHODS DH-8 were manufactured with strut thicknesses 0.10, 0.12, and 0.18 mm and mechanical testing performed. Stents were deployed into the infrarenal descending aorta (DAO) of nine minipigs. At insertion (nonsurvival = 2), 1 week (n = 2), 1 month (n = 2), and 9 months (n = 3) follow-up angiography, intravascular ultrasound and histopathology were performed. RESULTS There was superior recoil and collapse pressure with increasing strut thickness, with 0.18 mm having 1.0% elastic recoil and collapse pressure 0.75 Atmospheres. There was good wall apposition at insertion with 5 BDS (4 DH-8 and 1 DH-6) but suboptimal in 4 as the minipigs infrarenal DAO were >8 mm (deployed at iliac bifurcation). Structural integrity was maintained in 8 BDS with 1 DH-8 collapsed at 9 months, secondary to strut damage at insertion. No thrombosis was seen. There was mild inflammation and neointimal proliferation at 1 week and 1 month, but a moderate inflammatory response at 9 months. CONCLUSIONS DH-8 with increased strut thickness had acceptable mechanical properties at the cost of an increased inflammatory response. Miniaturization to improve delivery and further investigation on the long-term inflammatory profile of thicker struts, including through degradation, is needed. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Carrie E Herbert
- Division of Cardiology, Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas
| | | | - Tré R Welch
- Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas
| | - Jian Wang
- Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas
| | | | - Joseph M Forbess
- Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular and Thoracic Surgery, UT Southwestern Medical Center, Dallas, Texas
| | - Alan W Nugent
- Division of Cardiology, Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas
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Welch TR, Eberhart RC, Banerjee S, Chuong CJ. Mechanical Interaction of an Expanding Coiled Stent with a Plaque-Containing Arterial Wall: A Finite Element Analysis. Cardiovasc Eng Technol 2015; 7:58-68. [PMID: 26621671 DOI: 10.1007/s13239-015-0249-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 11/16/2015] [Indexed: 11/30/2022]
Abstract
Wall injury is observed during stent expansion within atherosclerotic arteries, related in part to stimulation of the inflammatory process. Wall stress and strain induced by stent expansion can be closely examined by finite element analysis (FEA), thus shedding light on procedure-induced sources of inflammation. The purpose of this work was to use FEA to examine the interaction of a coiled polymer stent with a plaque-containing arterial wall during stent expansion. An asymmetric fibrotic plaque-containing arterial wall model was created from intravascular ultrasound (IVUS) images of a diseased artery. A 3D model for a coil stent at unexpanded state was generated in SolidWorks. They were imported into ANSYS for FEA of combined stent expansion and fibrotic plaque-distortion. We simulated the stent expansion in the plaqued lumen by increasing balloon pressure from 0 to 12 atm in 1 atm step. At increasing pressure, we examined how the expanding stent exerts forces on the fibrotic plaque and vascular wall components, and how the latter collectively resist and balance the expansive forces from the stent. Results show the expanding coiled stent creates high stresses within the plaque and the surrounding fibrotic capsule. Lower stresses were observed in adjacent medial and adventitial layers. High principal strains were observed in plaque and fibrotic capsule. The results suggest fibrotic capsule rupture might occur at localized regions. The FEA/IVUS method can be adapted for routine examination of the effects of the expansion of selected furled stents against IVUS-reconstructed diseased vessels, to improve stent deployment practices.
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Affiliation(s)
- Tré R Welch
- Division of Pediatric Cardiothoracic Surgery, Department of Cardiovascular Thoracic Surgery, University of Texas at Southwestern Medical Center of Dallas, Dallas, TX, 75390-9130, USA.
| | - Robert C Eberhart
- Department of Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390-9130, USA.,Bioengineering Department, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Subhash Banerjee
- Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390-9130, USA
| | - Cheng-Jen Chuong
- Bioengineering Department, University of Texas at Arlington, Arlington, TX, 76019, USA
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