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Kohata Y, Ohta M, Jin K, Anzai H. Effects of helical centerline stent vs. straight stent placement on blood flow velocity. Front Med Technol 2023; 5:1196125. [PMID: 37333882 PMCID: PMC10272720 DOI: 10.3389/fmedt.2023.1196125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/17/2023] [Indexed: 06/20/2023] Open
Abstract
As an approach to maintain patency in femoropopliteal stenting, a helical stent configuration was proposed, which showed improved patency in clinical trials. However, the effects of helical stent placement on the flow have not been quantitatively analyzed. The purpose of this study was to estimate flow velocities to quantify the influence of helical stent placement. Helical and straight stents were implanted in three healthy pigs, and the flow velocities were estimated using the time-intensity curve (TIC) in the angiography images. The angiographic images indicated thinning of the leading edge of the contrast medium through the helically deformed artery, which was not observed in the straight stent. The slower rise of the TIC peak in the helical stent indicated faster travel of this thinner edge. Arterial expansion due to stenting was observed in all cases, and the expansion rate varied according to location. All cases of helical stent implantation showed that velocity was maintained (55.0%-71.3% velocity retention), unlike for straight stent implantation (43.0%-68.0% velocity retention); however, no significant difference was observed.
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Affiliation(s)
- Yutaro Kohata
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Makoto Ohta
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
- ELyTMaXUMI 3757, CNRS – Université de Lyon – Tohoku University, International Joint Unit, Tohoku University, Sendai, Miyagi, Japan
| | - Kazuyoshi Jin
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Hitomi Anzai
- Biomedical Flow Dynamics Laboratory, The Institute of Fluid Science, Tohoku University, Sendai, Japan
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Zhao G, Liu J, Liu M, Tian Y, Cheng J, Liu W, Ni Z. Influence of parameters on mechanical properties of poly (L-lactic acid) helical stents. J Biomed Mater Res B Appl Biomater 2022; 110:1705-1712. [PMID: 35157351 DOI: 10.1002/jbm.b.35031] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 12/08/2021] [Accepted: 01/29/2022] [Indexed: 12/17/2022]
Abstract
With better biocompatibility, bioresorbable poly (L-lactic acid) (PLLA) helical stents are expected to replace the commonly used metallic stents. However, due to the great difference between the material properties of PLLA and those of metals, the current research results on mechanical properties of stents will not be applicative. In this article, the effects of i on the radial compression performance and bending stiffness of PLLA helical stents were systematically studied, and the effect of temperature on the radial compression performance of the helical stent was investigated. The findings obtained indicate that the reduction of initial pitch angle and initial diameter can enhance the radial compression performance. The reduction of initial pitch angle and the increase of initial diameter can weaken the bending stiffness of the helical stent. Moreover, the increase of temperature will reduce the radial stiffness and peak compression force of the helical stent. A favorable agreement between the theoretical and experimental results of radial compression properties was found in stents with the initial pitch angle between 14° and 21° and all initial diameters. This work can provide suggestions for the use of the theoretical formula in structure design of the helical stent.
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Affiliation(s)
- Gutian Zhao
- School of Mechanical Engineering, Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, Southeast University, Nanjing, China
| | - Jiaming Liu
- 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
| | - Jie Cheng
- 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
| | - 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
Background: The MIMICS-3D study aimed to assess the safety and effectiveness of the BioMimics 3D Vascular Stent System for the treatment of symptomatic femoropopliteal artery disease in a real-world patient population. Patients and methods: Consecutive participants who were scheduled for implantation of the BioMimics 3D stent were enrolled in the prospective, observational, multicenter study. The primary effectiveness outcome was freedom from clinically driven target lesion revascularization at 12 months and the primary safety outcome was a composite of major adverse events comprising death, major target limb amputation, or clinically driven target lesion revascularization at 30 days. Outcomes through 24 months are reported. Results: A total of 507 patients (70±10 years, 65.5% male sex) were enrolled and treated with the study stent. 24.0% had critical limb-threatening ischemia, lesion length was 127±92 mm, and 56.8% of lesions were totally occluded. The Kaplan-Meier (KM) estimate of freedom from clinically driven target lesion revascularization at twelve-months was 90.6% (95% CI: 87.9%-93.3%) and the 30-day primary safety outcome occurred in 1.2% (95% CI: 0.5%-2.7%) of participants. At 24 months, clinical improvement was achieved in 86.6% and the KM estimate of freedom from clinically driven target lesion revascularization was 82.8% (95% CI: 79.4%-86.4%). The KM estimate of freedom from loss of primary patency according to PSVR >2.4 was 78.6% (95% CI: 74.7%-82.4%). Survival distribution functions regarding primary patency were lower with long lesions (>150 mm; log-rank p<0.001) but did not differ significantly between participants with or without critical limb-threatening ischemia (log-rank p=0.07). Conclusions: Endovascular treatment of atherosclerotic femoropopliteal lesions with the BioMimics 3D Vascular Stent System is efficacious and safe in a real-world setting.
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Affiliation(s)
| | - Thomas Zeller
- Universitätsklinikum Freiburg Herzzentrum, Bad Krozingen, Germany
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Tarbell J, Mahmoud M, Corti A, Cardoso L, Caro C. The role of oxygen transport in atherosclerosis and vascular disease. J R Soc Interface 2020; 17:20190732. [PMID: 32228404 PMCID: PMC7211472 DOI: 10.1098/rsif.2019.0732] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/11/2020] [Indexed: 12/18/2022] Open
Abstract
Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system-the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.
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Affiliation(s)
- John Tarbell
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Marwa Mahmoud
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Andrea Corti
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Luis Cardoso
- Biomedical Engineering Department, The City College of New York, New York, NY, USA
| | - Colin Caro
- Department of Bioengineering, Imperial College London, London, UK
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Paryab N, Cronin DS, Lee-Sullivan P. Finite element methods to analyze helical stent expansion. Int J Numer Method Biomed Eng 2014; 30:339-352. [PMID: 24123985 DOI: 10.1002/cnm.2605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 08/23/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
Helical polymeric stents have been proposed as a suitable geometry for biodegradable drug-eluting polymer-based stents. However, helical stents often experience nonuniform local expansion (dog boning), which can prohibit full stent expansion using conventional methods. The development of stents and deployment methods is challenging and can be supported by numerical analysis; however, this complex problem is often approached with simplified boundary conditions that may not be appropriate for helical stents. The finite element method (explicit and implicit) was used to investigate three common stent expansion approaches with a focus on helical stent geometry, which differs from traditional wire mesh stent expansion. Although each of the three methods considered provided some insight into the expansion characteristics, common displacement controlled, and uniform expansion methods were not able to demonstrate the characteristic local deformations observed in expansion. A coupled stent-balloon model, although computationally expensive, was able to demonstrate the expected nonuniform deformation. To address nonuniform expansion, a progressive expansion approach has been investigated and verified numerically. This method may also provide a suitable solution for nonuniform expansion in other stent designs by minimizing loading and potential damage to the artery that can occur during stent deployment.
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Affiliation(s)
- Nasim Paryab
- University of Waterloo, Waterloo, Ontario, Canada
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