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Guo J, Mao L, Yu X, Song C, Zhao X. Design and Biomechanical Analysis of a Novel Retrievable Peripheral Vascular Stent. J Med Device 2020. [DOI: 10.1115/1.4046796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Abstract
Structurally retrievable drug-eluting stents may have valuable clinical applications because they do not leave any foreign materials inside the patient's body. This article presents a novel design of retrievable peripheral vascular stent and the results from biomechanical analysis of its performance. Using the finite element analysis method, principal parameters of the stent were studied. Moreover, to ensure the practicability of the retrieval process, simulation, and in vitro experiments were performed. The retrieval force reached the maximum value when the whole retrievable part had been retrieved. Furthermore, the force was gradually increased during the retrieval process and remained constant after the main part had been retrieved. When the stent was being compressed, the maximum strain of the stent occurred at the connection between the stent's retrieval part and the main body part, at a value of 4%. The index of nonuniformity of the stent was too small to be counted both at the end of the compression and self-expansion processes. With the increase of moment, the bending stiffness (EI) of the stent decreased gradually. After bending moment was applied, the large strain region was mainly located in the stent's main body part rather than the retrieval part. The results of preliminary stent retrieval experiments demonstrated that the stent could be retrieved successfully. This novel retrievable stent displays promising biomechanical performance. The preliminary experiments demonstrated that the stent could be retrieved smoothly from the blood vessels.
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Affiliation(s)
- Jingzhen Guo
- Shanghai Institute for Minimally Invasive Therapy, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Lin Mao
- Shanghai Institute for Minimally Invasive Therapy, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Xitong Yu
- Shanghai Institute for Minimally Invasive Therapy, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Chengli Song
- Shanghai Institute for Minimally Invasive Therapy, School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, Shanghai 200093, China
| | - Xue Zhao
- Department of Cardiology, Shanghai Eastern Hepatobiliary Surgery Hospital, 225 Changhai Road, Shanghai 200438, China
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Trela JM, Dechant JE, Culp WT, Whitcomb MB, Palm CA, Nieto JE. Use of an Absorbable Urethral Stent for the Management of a Urethral Stricture in a Stallion. Vet Surg 2016; 45:O41-O48. [DOI: 10.1111/vsu.12530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 05/26/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Jan M. Trela
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Julie E. Dechant
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - William T. Culp
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Mary B. Whitcomb
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Carrie A. Palm
- School of Veterinary Medicine; University of California-Davis; Davis California
| | - Jorge E. Nieto
- School of Veterinary Medicine; University of California-Davis; Davis California
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Park JH, Song HY, Shin JH, Kim JH, Jun EJ, Cho YC, Kim SH, Park J. Polydioxanone biodegradable stent placement in a canine urethral model: analysis of inflammatory reaction and biodegradation. J Vasc Interv Radiol 2014; 25:1257-1264.e1. [PMID: 24912878 DOI: 10.1016/j.jvir.2014.03.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Revised: 03/20/2014] [Accepted: 03/21/2014] [Indexed: 11/17/2022] Open
Abstract
PURPOSE To investigate the inflammatory reaction and perform quantitative analysis of biodegradation after placement of a polydioxanone (PDO) biodegradable stent in a canine urethral model. MATERIALS AND METHODS PDO biodegradable stents were placed in the proximal and distal urethra of nine male mongrel dogs. The dogs were euthanized 4 weeks (group A; n = 3), 8 weeks (group B; n = 3), or 12 weeks (group C; n = 3) after stent placement. The luminal diameter of the stent-implanted urethra was assessed by follow-up retrograde urethrography, and histologic findings were obtained after the dogs were killed. Stents were removed after euthanasia, and their surface morphology and molecular weight were evaluated. Hematologic examination was performed to evaluate inflammatory reaction. RESULTS Stent placement was technically successful in all dogs. The average luminal diameter gradually decreased. The average number of epithelial layers (2.93 vs 4.42; P < .001), the average thickness of papillary projection (0.80 mm vs 1.28 mm; P < .001), and the average thickness of submucosal fibrosis (0.34 mm vs 0.49 mm ; P < .001) were significantly increased in group B versus group A. There were no significant differences between group B and group C. The average inflammatory cell infiltration did not differ significantly in the three groups. Molecular weight losses were 54% in group A and 84% in group B. In group C, PDO stents were completely decomposed. CONCLUSIONS An experimental study in a canine urethral model has demonstrated acceptable inflammatory reaction with gradually increasing granulation tissue but no luminal obstruction within 12 weeks.
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Affiliation(s)
- Jung-Hoon Park
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Ho-Young Song
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
| | - Ji Hoon Shin
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Jin Hyoung Kim
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Eun Jung Jun
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Young Chul Cho
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Soo Hwan Kim
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Jihong Park
- Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea
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Evaluation of the anti-migration effect of barbed prostatic stents: in vitro study in urethra-mimicking bovine pericardium phantoms. Cardiovasc Intervent Radiol 2012; 36:229-36. [PMID: 22829302 DOI: 10.1007/s00270-012-0449-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE This study was designed to compare the migration rates of covered stents with eight, four, and zero barbs in urethra-mimicking bovine pericardium models. METHODS Three types of polytetrafluoroethylene-covered retrievable self-expandable prostatic stents, with eight, four, and zero barbs, were tested in bovine pericardium models, consisting of normal saline-filled acrylic containers with tubes at both ends and a replica of the human urethra. The barbs were 2 mm in length and projected 60° toward the urinary bladder. The anti-migration force (AMF) and resistance force against stent removal (RFSR) were measured by an automatic push-pull gauge system at a fixed rate (2 mm/s). RESULTS Significant differences in AMF among the three stent types were detected (P < 0.001). Median AMF was far greater for eight-barbed than for four-barbed stents (11.96 vs. 7.55 N, P = 0.003). For stent removal, the difference between 4- and 8-barbed stents were not significant in median static (5.54 vs. 6.08 N, P = 0.15) or sliding (prostatic urethra, 5.32 vs. 5.59 N, P = 0.65; membranous urethra, 7.78 vs. 8.57 N, P = 0.364) RFSR. No perforations or scratched traces were observed during removal of these stents. CONCLUSIONS The inclusion of eight barbs projecting 60° toward the urinary bladder were not only effective against stent migration in this model but suggests that these stents may be suitable for the treatment of prostatic urethral strictures without severely irritating the tissue. However, whether these results translate into living urethral tissue is unclear, necessitating further studies.
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Temporary placement of covered retrievable expandable nitinol stents with barbs in high-risk surgical patients with benign prostatic hyperplasia: work in progress. J Vasc Interv Radiol 2011; 22:1420-6. [PMID: 21840225 DOI: 10.1016/j.jvir.2011.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 06/18/2011] [Accepted: 06/22/2011] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To report the use of a newly constructed, covered, retrievable, expandable nitinol stent with barbs to overcome the problem of stent migration associated with conventional covered prostatic expandable stents and to evaluate prospectively the technical feasibility and clinical effectiveness of the stents in patients with benign prostatic hyperplasia (BPH). MATERIALS AND METHODS A covered retrievable expandable nitinol stent with four barbs was placed with use of an 18-F stent delivery system in seven consecutive patients with symptomatic BPH who had high operative risks. Age range of patients was 62-83 years (mean 74 years). In cases in which the stent migrated, it was replaced with a stent with eight barbs. The stents were routinely removed 4 months after placement using a 21-F stent removal set. RESULTS Stent placement was technically successful and well tolerated in six of the seven patients. The remaining patient needed a second stent placement after removal of the first stent. The stent with four barbs migrated into the urinary bladder in four patients (57%); three of these patients received a second stent with eight barbs with good results, and the fourth patient did not need further treatment because his symptoms improved. Routine removal of the stent 4 months after placement was performed in three of the seven patients with good results. CONCLUSIONS Retrievable stents with eight barbs seem to overcome the problem of stent migration associated with conventional prostatic expandable stents. Preliminary results suggest that stents with barbs are both feasible and effective in patients with BPH.
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Evaluation of Formation of Granulation Tissue Caused by Metallic Stent Placement in a Rat Urethral Model. J Vasc Interv Radiol 2010; 21:1884-90. [DOI: 10.1016/j.jvir.2010.07.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 03/19/2010] [Accepted: 07/14/2010] [Indexed: 11/19/2022] Open
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Temporary Placement of a Covered, Retrievable, Barbed Stent for the Treatment of Hormone-induced Benign Prostatic Hyperplasia: Technical Feasibility and Histologic Changes in Canine Prostates. J Vasc Interv Radiol 2010; 21:1429-35. [DOI: 10.1016/j.jvir.2010.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 03/25/2010] [Accepted: 05/10/2010] [Indexed: 11/21/2022] Open
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Choi R, Lee S, Hyun C. Urethral stenting in a cat with refractory obstructive feline lower urinary tract disease. J Vet Med Sci 2009; 71:1255-9. [PMID: 19801911 DOI: 10.1292/jvms.71.1255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A 10-year-old male Korean domestic short-haired cat was presented with refractory lower urinary tract obstruction. The cat was treated by urethral stent placement using a self-expanding nitinol intraluminal stent (Zilver 535 biliary stents, COOK, U.S.A.) subsequent with balloon expansion. Although the cat showed 2 days of transient hematuria after the stent placement, no further obstruction was occurred after the stent placement. Follow-up studies performed at monthly intervals have found no re-stenosis or particular complications, to date.
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Affiliation(s)
- Ran Choi
- Section of Small Animal Internal Medicine, School of Veterinary Medicine, Kangwon National University, Chuncheon, South Korea
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