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Shen X, Xu Y, Li H, Wang L, Sun P, Liu Q, Chen J, He Z. Mechanical behaviors of a new elliptical valve stent in bicuspid aortic valve. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 250:108173. [PMID: 38615386 DOI: 10.1016/j.cmpb.2024.108173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/05/2024] [Accepted: 04/10/2024] [Indexed: 04/16/2024]
Abstract
BACKGROUND AND OBJECTIVE The conventional valve stents that are cylindrical in shape will become elliptical when implanted in bicuspid aortic valve, thereby reducing the durability of the artificial valve. In this study, a new design of valve stent is presented where valve stents have elliptical cross-section at the annulus and it is expected to have better expandability and circle shape during the interaction between the stent and bicuspid aortic valve, thereby extending the durability of artificial valve. METHODS Finite element method (FEM) is used to study the mechanical behavior of the novel valve stent in the bicuspid aortic valve. The effects of three matching relationship between the ellipticity of the stents and the ellipticity of the annulus (i.e., the ellipticity of the stent is greater than, equal to and less than the annulus ellipticity, respectively) on the mechanical behavior of stent expansion are studied. In addition, the expansion mechanical behavior of the novel valve stent at different implantation depths is also compared. RESULTS Results indicate that novel valve stent implantation with elliptical features is superior to conventional circular valve stent. When the novel valve stent ellipticity is less than the annulus ellipticity, the ellipticity of the novel valve stent after implantation is smaller than that of the conventional circular valve stent. This indicated that the novel valve stent has better expandability and post-expansion shape, making artificial valve to have better durability. The risk of paravalvular leak after implantation is lowest when the novel valve stent ellipticity is less than annulus ellipticity. When the novel valve stent ellipticity coincides with annulus ellipticity, the aortic wall is subjected to greatest stress. With the increase of implantation depth, the stress on the novel valve stent decrease. CONCLUSIONS This study might provide insights for improving stent design for bicuspid aortic valve.
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Affiliation(s)
| | - Yue Xu
- Jiangsu University, China
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2
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Donahue CL, Westman CL, Faanes BL, Qureshi AM, Barocas VH, Aggarwal V. Finite element modeling with patient-specific geometry to assess clinical risks of percutaneous pulmonary valve implantation. Catheter Cardiovasc Interv 2024. [PMID: 38597297 DOI: 10.1002/ccd.31016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 03/10/2024] [Accepted: 03/19/2024] [Indexed: 04/11/2024]
Abstract
BACKGROUND Percutaneous pulmonary valve implantation (PPVI) is a non-surgical treatment for right ventricular outflow tract (RVOT) dysfunction. During PPVI, a stented valve, delivered via catheter, replaces the dysfunctional pulmonary valve. Stent oversizing allows valve anchoring within the RVOT, but overexpansion can intrude on the surrounding structures. Potentially dangerous outcomes include aortic valve insufficiency (AVI) from aortic root (AR) distortion and myocardial ischemia from coronary artery (CA) compression. Currently, risks are evaluated via balloon angioplasty/sizing before stent deployment. Patient-specific finite element (FE) analysis frameworks can improve pre-procedural risk assessment, but current methods require hundreds of hours of high-performance computation. METHODS We created a simplified method to simulate the procedure using patient-specific FE models for accurate, efficient pre-procedural PPVI (using balloon expandable valves) risk assessment. The methodology was tested by retrospectively evaluating the clinical outcome of 12 PPVI candidates. RESULTS Of 12 patients (median age 14.5 years) with dysfunctional RVOT, 7 had native RVOT and 5 had RV-PA conduits. Seven patients had undergone successful RVOT stent/valve placement, three had significant AVI on balloon testing, one had left CA compression, and one had both AVI and left CA compression. A model-calculated change of more than 20% in lumen diameter of the AR or coronary arteries correctly predicted aortic valve sufficiency and/or CA compression in all the patients. CONCLUSION Agreement between FE results and clinical outcomes is excellent. Additionally, these models run in 2-6 min on a desktop computer, demonstrating potential use of FE analysis for pre-procedural risk assessment of PPVI in a clinically relevant timeframe.
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Affiliation(s)
- Carly L Donahue
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minnesota, USA
| | - Claire L Westman
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minnesota, USA
| | - Brittany L Faanes
- Division of Pediatric Cardiology, Department of Pediatrics, University of Minnesota Masonic Children's Hospital, Minneapolis, Minnesota, USA
| | - Athar M Qureshi
- Department of Pediatrics, The Lillei Frank Abercombie Section of Pediatric Cardiology, Texas Children's Hospital and Baylor College of Medicine, Houston, Texas, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota, Twin Cities, Minnesota, USA
| | - Varun Aggarwal
- Division of Pediatric Cardiology, Department of Pediatrics, University of Minnesota Masonic Children's Hospital, Minneapolis, Minnesota, USA
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Marasco SF, Banham T, Gregory SD, Vu T, Stephens AF. Use of Sutureless Valve in Aortic Root Enlargement. Heart Lung Circ 2024; 33:92-98. [PMID: 38135591 DOI: 10.1016/j.hlc.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 10/22/2023] [Accepted: 10/30/2023] [Indexed: 12/24/2023]
Abstract
AIM The small aortic annulus is a surgical challenge in patients undergoing aortic valve replacement which may lead to patient prosthesis mismatch. Management options include aortic root enlargement, aortic root replacement, and the use of sutureless valves. In this case series, we report our results with aortic root enlargement, sutureless valve implantation, and benchtop modelling of the radial forces exerted. METHODS Five patients underwent aortic root enlargement and insertion of the Perceval valve as part of the management strategy to enlarge their effective orifice area. We further investigate this strategy with a benchtop model to quantify the radial forces exerted by the Perceval valve on the aortic annulus. Radial and hoop forces on the aortic annulus and inner ring of the Perceval valve were recorded using a Mylar force tester. RESULTS Five female patients with native annulus between 18mm-20mm underwent root enlargement and insertion of a Perceval S valve. The postoperative course was uncomplicated for all patients except for one who required a permanent pacemaker insertion. Transvalvular pressure gradients remained low at up to 4 years of follow-up (12 mmHg-21 mmHg), with no evidence of paravalvular leak. Benchtop testing demonstrated radial forces exerted at the annulus in all-size Perceval S valves to be within physiological variables, whereas compressive forces required to deform the valves were supraphysiological. CONCLUSIONS The deployment of a sutureless valve within a surgical enlarged aortic root is a feasible solution in patients with a small aortic root.
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Affiliation(s)
- Silvana F Marasco
- Cardiothoracic Surgery Unit, The Alfred Hospital, Melbourne, Vic, Australia; Department of Surgery, Monash University, Melbourne, Vic, Australia.
| | - Taylah Banham
- Cardiorespiratory Engineering and Technology Laboratory, Victorian Heart Hospital, Melbourne, Vic, Australia; Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Vic, Australia
| | - Shaun D Gregory
- Cardiorespiratory Engineering and Technology Laboratory, Victorian Heart Hospital, Melbourne, Vic, Australia; Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Vic, Australia
| | - Tony Vu
- Cardiothoracic Surgery Unit, The Alfred Hospital, Melbourne, Vic, Australia
| | - Andrew F Stephens
- Cardiorespiratory Engineering and Technology Laboratory, Victorian Heart Hospital, Melbourne, Vic, Australia; Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Vic, Australia
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4
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Lansakara M, Unai S, Ozaki S. Ozaki procedure-re-construction of aortic valve leaflets using autologous pericardial tissue: a review. Indian J Thorac Cardiovasc Surg 2023; 39:260-269. [PMID: 38093925 PMCID: PMC10713953 DOI: 10.1007/s12055-023-01635-z] [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: 09/19/2023] [Revised: 10/12/2023] [Accepted: 10/23/2023] [Indexed: 12/17/2023] Open
Abstract
The Ozaki procedure has emerged as a valuable option for treating various aortic valve pathologies. This review article delves into the intricacies of this innovative surgical approach by exploring its adaptation to the complex anatomy and physiology of the aortic root. The diverse etiologies of aortic valve diseases, ranging from congenital anomalies to degenerative changes, make treatment selection a complex challenge. Aortic valve replacement has traditionally been the gold standard, but emerging evidence supports valve repair techniques, emphasizing the importance of preserving native tissue. Nevertheless, issues like lifelong anticoagulation with mechanical valves and patient-prosthetic mismatch remain. The Ozaki procedure offers a compelling alternative by utilizing autologous pericardium or a tissue substitute to construct new aortic valve leaflets. This technique, standardized by Dr. Ozaki in 2007, provides a customizable and adaptable solution. The article highlights the anatomy of the aortic root, emphasizing the critical role of the sinus of Valsalva and interleaflet triangles in maintaining proper valve function. The procedure's unique adaptation to aortic root dynamics allows for reduced mechanical stress during systole and diastole, mimicking the natural valve's behavior. Furthermore, Ozaki leaflets exhibit promising hemodynamics and reduced risks of complications, such as permanent pacemaker implantation and patient-prosthetic mismatch. The use of autologous pericardium in the Ozaki procedure presents advantages, including enhanced tissue strength, minimal immunogenicity, and reduced risk of immune-mediated calcification. These factors contribute to the longevity and resilience of the reconstructed valve. This comprehensive review aims to shed light on the procedure's intricacies, its alignment with aortic root anatomy and physiology, and its potential as a valuable tool in the armamentarium of aortic surgeons.
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Affiliation(s)
| | - Shinya Unai
- The Peter and Elizabeth C. Tower and Family Endowed Chair in Cardiothoracic Research, Aortic Valve Center, Heart Vascular and Thoracic Institute, Cleveland Clinic, 9500 Euclid Ave., Desk J4-1, Cleveland, OH 44915 USA
| | - Shigeyuki Ozaki
- Department of Cardiovascular Surgery, Toho University Ohashi Hospital, 2-17-6 Ohashi, Meguro-Ku, Tokyo, 153-8515 Japan
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Bernini M, Hellmuth R, Dunlop C, Ronan W, Vaughan TJ. Recommendations for finite element modelling of nickel-titanium stents-Verification and validation activities. PLoS One 2023; 18:e0283492. [PMID: 37556457 PMCID: PMC10411813 DOI: 10.1371/journal.pone.0283492] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 03/11/2023] [Indexed: 08/11/2023] Open
Abstract
The objective of this study is to present a credibility assessment of finite element modelling of self-expanding nickel-titanium (Ni-Ti) stents through verification and validation (VV) activities, as set out in the ASME VV-40 standard. As part of the study, the role of calculation verification, model input sensitivity, and model validation is examined across three different application contexts (radial compression, stent deployment in a vessel, fatigue estimation). A commercially available self-expanding Ni-Ti stent was modelled, and calculation verification activities addressed the effects of mesh density, element integration and stable time increment on different quantities of interests, for each context of use considered. Sensitivity analysis of the geometrical and material input parameters and validation of deployment configuration with in vitro comparators were investigated. Results showed similar trends for global and local outputs across the contexts of use in response to the selection of discretization parameters, although with varying sensitivities. Mesh discretisation showed substantial variability for less than 4 × 4 element density across the strut cross-section in radial compression and deployment cases, while a finer grid was deemed necessary in fatigue estimation for reliable predictions of strain/stress. Element formulation also led to substantial variation depending on the chosen integration options. Furthermore, for explicit analyses, model results were highly sensitive to the chosen target time increment (e.g., mass scaling parameters), irrespective of whether quasistatic conditions were ensured (ratios of kinetic and internal energies below 5%). The higher variability was found for fatigue life simulation, with the estimation of fatigue safety factor varying up to an order of magnitude depending on the selection of discretization parameters. Model input sensitivity analysis highlighted that the predictions of outputs such as radial force and stresses showed relatively low sensitivity to Ni-Ti material parameters, which suggests that the calibration approaches used in the literature to date appear reasonable, but a higher sensitivity to stent geometry, namely strut thickness and width, was found. In contrast, the prediction of vessel diameter following deployment was least sensitive to numerical parameters, and its validation with in vitro comparators offered a simple and accurate (error ~ 1-2%) method when predicting diameter gain, and lumen area, provided that the material of the vessel is appropriately characterized and modelled.
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Affiliation(s)
- Martina Bernini
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
- Vascular Flow Technologies, Dundee, United Kingdom
| | | | - Craig Dunlop
- Vascular Flow Technologies, Dundee, United Kingdom
| | - William Ronan
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
| | - Ted J. Vaughan
- Biomechanics Research Centre (BioMEC), College of Science and Engineering, University of Galway, Galway, Ireland
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Carbonaro D, Zambon S, Corti A, Gallo D, Morbiducci U, Audenino AL, Chiastra C. Impact of nickel-titanium super-elastic material properties on the mechanical performance of self-expandable transcatheter aortic valves. J Mech Behav Biomed Mater 2023; 138:105623. [PMID: 36535095 DOI: 10.1016/j.jmbbm.2022.105623] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 12/06/2022] [Accepted: 12/11/2022] [Indexed: 12/14/2022]
Abstract
Self-expandable transcatheter aortic valves (TAVs) elastically resume their initial shape when implanted without the need for balloon inflation by virtue of the nickel-titanium (NiTi) frame super-elastic properties. Experimental findings suggest that NiTi mechanical properties can vary markedly because of a strong dependence on the chemical composition and processing operations. In this context, this study presents a computational framework to investigate the impact of the NiTi super-elastic material properties on the TAV mechanical performance. Finite element (FE) analyses of TAV implantation were performed considering two different TAV frames and three idealized aortic root anatomies, evaluating the device mechanical response in terms of pullout force magnitude exerted by the TAV frame and peak maximum principal stress within the aortic root. The widely adopted NiTi constitute model by Auricchio and Taylor (1997) was used. A multi-parametric sensitivity analysis and a multi-objective optimization of the TAV mechanical performance were conducted in relation to the parameters of the NiTi constitutive model. The results highlighted that: five NiTi material model parameters (EA, σtLS, σtUS, σtUE and σcLS) are significantly correlated with the FE outputs; the TAV frame geometry and aortic root anatomy have a marginal effect on the level of influence of each NiTi material parameter; NiTi alloy candidates with pareto-optimal characteristics in terms of TAV mechanical performance can be successfully identified. In conclusion, the proposed computational framework supports the TAV design phase, providing information on the relationship between the super-elastic behavior of the supplied NiTi alloys and the device mechanical response.
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Affiliation(s)
- Dario Carbonaro
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Sara Zambon
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Anna Corti
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Diego Gallo
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Umberto Morbiducci
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Alberto L Audenino
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
| | - Claudio Chiastra
- PoliTo(BIO)Med Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
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7
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Vellaparambil R, Han WS, Di Giovanni P, Avril S. Potential of auxetic designs in endovascular aortic repair: A computational study of their mechanical performance. J Mech Behav Biomed Mater 2023; 138:105644. [PMID: 36608533 DOI: 10.1016/j.jmbbm.2022.105644] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/01/2022] [Accepted: 12/25/2022] [Indexed: 12/27/2022]
Abstract
With the rising popularity of endovascular aortic repair (EVAR) for aortic aneurysms and dissections, there is a crucial need for investigating the delayed appearance of post-EVAR complications such as stent-graft kinking, fracture and migration respectively. These complications have been noted to be influenced by the radial stiffness and bending flexibility attributes of stent-grafts. Auxetic designs with negative Poisson's ratio offer interesting advantages such as enhanced fracture toughness, superior indentation resistance and adaptive stiffness in response to intricate morphology for stenting applications over conventional stent designs. The objective of this study is to propose different auxetic stent candidates and to compare their mechanical performance with two conventional stent candidates for endovascular applications using numerical simulation through crimp/crushing tests for their radial stiffness and three-point bending/kinking tests for their flexibility, respectively. The results demonstrate that the novel hybrid auxetic designs (CRE and CSTAR) possess the best trade-off between radial stiffness and bending flexibility characteristics among all candidates for stent-graft applications.
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Affiliation(s)
- Rahul Vellaparambil
- Mines Saint-Etienne, Univ Lyon, Univ Jean Monnet, Etablissement Francais du Sang, INSERM, U 1059 Sainbiose, Centre CIS, F - 42023, Saint-Etienne, France; R&D Department, HSL S.R.L, Trento, Italy
| | - Woo-Suck Han
- Mines Saint-Etienne, Univ Lyon, Univ Jean Monnet, Etablissement Francais du Sang, INSERM, U 1059 Sainbiose, Centre CIS, F - 42023, Saint-Etienne, France
| | | | - Stéphane Avril
- Mines Saint-Etienne, Univ Lyon, Univ Jean Monnet, Etablissement Francais du Sang, INSERM, U 1059 Sainbiose, Centre CIS, F - 42023, Saint-Etienne, France.
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8
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Tang Y, Li M, Wang T, Dong X, Hu W, Sitti M. Wireless Miniature Magnetic Phase-Change Soft Actuators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204185. [PMID: 35975467 PMCID: PMC7613683 DOI: 10.1002/adma.202204185] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/09/2022] [Indexed: 05/28/2023]
Abstract
Wireless miniature soft actuators are promising for various potential high-impact applications in medical, robotic grippers, and artificial muscles. However, these miniature soft actuators are currently constrained by a small output force and low work capacity. To address such challenges, a miniature magnetic phase-change soft composite actuator is reported. This soft actuator exhibits an expanding deformation and enables up to a 70 N output force and 175.2 J g-1 work capacity under remote magnetic radio frequency heating, which are 106 -107 times that of traditional magnetic soft actuators. To demonstrate its capabilities, a wireless soft robotic device is first designed that can withstand 0.24 m s-1 fluid flows in an artery phantom. By integrating it with a thermally-responsive shape-memory polymer and bistable metamaterial sleeve, a wireless reversible bistable stent is designed toward future potential angioplasty applications. Moreover, it can additionally locomote inside and jump out of granular media. At last, the phase-change actuator can realize programmable bending deformations when a specifically designed magnetization profile is encoded, enhancing its shape-programming capability. Such a miniature soft actuator provides an approach to enhance the mechanical output and versatility of magnetic soft robots and devices, extending their medical and other potential applications.
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Affiliation(s)
- Yichao Tang
- School of Mechanical Engineering Tongji University Shanghai 201804, China; Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany
| | - Mingtong Li
- Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany; Institute of Functional Nano & Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Soochow University Suzhou, Jiangsu 215123, China
| | - Tianlu Wang
- Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany; Institute for Biomedical Engineering ETH Zurich Zurich 8092, Switzerland
| | - Xiaoguang Dong
- Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany; of Mechanical Engineering Vanderbilt University Nashville, TN 37215, USA; Vanderbilt Institute for Surgery and Engineering Vanderbilt University Nashville, TN 37215, USA
| | - Wenqi Hu
- Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany
| | - Metin Sitti
- Physical Intelligence Department Max Planck Institute for Intelligent Systems 70569, Stuttgart, Germany; Institute for Biomedical Engineering ETH Zurich Zurich 8092, Switzerland; School of Medicine and College of Engineering Koç University Istanbul 34450, Turkey
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9
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Barati S, Fatouraee N, Nabaei M, Petrini L, Migliavacca F, Luraghi G, Matas JFR. Patient-specific multi-scale design optimization of transcatheter aortic valve stents. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106912. [PMID: 35640391 DOI: 10.1016/j.cmpb.2022.106912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/09/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE Transcatheter aortic valve implantation (TAVI) has become the standard treatment for a wide range of patients with aortic stenosis. Although some of the TAVI post-operative complications are addressed in newer designs, other complications and lack of long-term and durability data on the performance of these prostheses are limiting this procedure from becoming the standard for heart valve replacements. The design optimization of these devices with the finite element and optimization techniques can help increase their performance quality and reduce the risk of malfunctioning. Most performance metrics of these prostheses are morphology-dependent, and the design and the selection of the device before implantation should be planned for each individual patient. METHODS In this study, a patient-specific aortic root geometry was utilized for the crimping and implantation simulation of 50 stent samples. The results of simulations were then evaluated and used for developing regression models. The strut width and thickness, the number of cells and patterns, the size of stent cells, and the diameter profile of the stent were optimized with two sets of optimization processes. The objective functions included the maximum crimping strain, radial strength, anchorage area, and the eccentricity of the stent. RESULTS The optimization process was successful in finding optimal models with up to 40% decrease in the maximum crimping strain, 261% increase in the radial strength, 67% reduction in the eccentricity, and about an eightfold increase in the anchorage area compared to the reference device. CONCLUSIONS The stents with larger distal diameters perform better in the selected objective functions. They provide better anchorage in the aortic root resulting in a smaller gap between the device and the surrounding tissue and smaller contact pressure. This framework can be used in designing patient-specific stents and improving the performance of these devices and the outcome of the implantation process.
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Affiliation(s)
- Sara Barati
- Biological Fluid Dynamics Research Laboratory, Biomedical Engineering Department, Amirkabir University of Technology, 350 Hafez Ave, Tehran, Iran
| | - Nasser Fatouraee
- Biological Fluid Dynamics Research Laboratory, Biomedical Engineering Department, Amirkabir University of Technology, 350 Hafez Ave, Tehran, Iran.
| | - Malikeh Nabaei
- Biological Fluid Dynamics Research Laboratory, Biomedical Engineering Department, Amirkabir University of Technology, 350 Hafez Ave, Tehran, Iran
| | - Lorenza Petrini
- Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy
| | - Giulia Luraghi
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
| | - Josè Felix Rodriguez Matas
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials, and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, Milan 20133, Italy.
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10
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Bernini M, Colombo M, Dunlop C, Hellmuth R, Chiastra C, Ronan W, Vaughan TJ. Oversizing of self-expanding nitinol vascular stents – A biomechanical investigation in the superficial femoral artery. J Mech Behav Biomed Mater 2022; 132:105259. [DOI: 10.1016/j.jmbbm.2022.105259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/20/2022] [Accepted: 04/29/2022] [Indexed: 10/18/2022]
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Russ JB, Li RL, Herschman AR, Waisman H, Vedula V, Kysar JW, Kalfa D. Design optimization of a cardiovascular stent with application to a balloon expandable prosthetic heart valve. MATERIALS & DESIGN 2021; 209:109977. [PMID: 34366534 PMCID: PMC8336925 DOI: 10.1016/j.matdes.2021.109977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A cardiovascular stent design optimization method is proposed with application to a pediatric balloon-expandable prosthetic heart valve. The prosthetic valved conduit may be expanded to a larger permanent diameter in vivo via subsequent transcatheter balloon dilation procedures. While multiple expandable prosthetic heart valves are currently at different stages of development, this work is focused on one particular design in which a stent is situated inside of an expandable polymeric valved conduit. Since the valve and conduit must be joined with a robust manufacturing technique, a polymeric glue layer is inserted between the two, which results in radial retraction of the valved region after expansion. Design of an appropriate stent is proposed to counteract this phenomenon and maintain the desired permanent diameter throughout the device after a single non-compliant balloon dilation procedure. The finite element method is used to compute performance metrics related to the permanent expansion diameter and required radial force. Additionally, failure due not only to high cycle fatigue but also due to ductile fracture is incorporated into the design study through the use of an existing ductile fracture criterion for metals. Surrogate models are constructed with the results of the high fidelity simulations and are subsequently used to numerically obtain a set of Pareto-optimal stent designs. Finally, a single design is identified by optimizing a normalized aggregate objective function with equal weighting of all design objectives.
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Affiliation(s)
- Jonathan B. Russ
- Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, USA
| | - Richard L. Li
- Columbia University, Department of Mechanical Engineering, New York, NY, USA
- Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children’s Hospital, Columbia University Medical Center, New York, NY, USA
| | - Abigail R. Herschman
- Columbia University, Department of Mechanical Engineering, New York, NY, USA
- Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children’s Hospital, Columbia University Medical Center, New York, NY, USA
| | - Haim Waisman
- Columbia University, Department of Civil Engineering and Engineering Mechanics, New York, NY, USA
| | - Vijay Vedula
- Columbia University, Department of Mechanical Engineering, New York, NY, USA
| | - Jeffrey W. Kysar
- Columbia University, Department of Mechanical Engineering, New York, NY, USA
- Department of Otolaryngology Head and Neck Surgery, Columbia University Medical Center, New York, NY, USA
| | - David Kalfa
- Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children’s Hospital, Columbia University Medical Center, New York, NY, USA
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12
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A computational optimization study of a self-expandable transcatheter aortic valve. Comput Biol Med 2021; 139:104942. [PMID: 34700254 DOI: 10.1016/j.compbiomed.2021.104942] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/11/2021] [Accepted: 10/11/2021] [Indexed: 11/21/2022]
Abstract
Developing an efficient stent frame for transcatheter aortic valves (TAV) needs thorough investigation in different design and functional aspects. In recent years, most TAV studies have focused on their clinical performance, leaflet design, and durability. Although several optimization studies on peripheral stents exist, the TAV stents have different functional requirements and need to be explicitly studied. The aim of this study is to develop a cost-effective optimization framework to find the optimal TAV stent design made of Ni-Ti alloy. The proposed framework focuses on minimizing the maximum strain occurring in the stent during crimping, making use of a simplified model of the stent to reduce computational cost. The effect of the strut cross-section of the stent, i.e., width and thickness, and the number and geometry of the repeating units of the stent (both influencing the cell size) on the maximum strain is investigated. Three-dimensional simulations of the crimping process are used to verify the validity of the simplified representation of the stent, and the radial force has been calculated for further evaluation. The results suggest the key role of the number of cells (repeating units) and strut width on the maximum strain and, consequently, on the stent design. The difference in terms of the maximum strain between the simplified and the 3D model was less than 5%, confirming the validity of the adopted modeling strategy and the robustness of the framework to improve the TAV stent designs through a simple, cost-effective, and reliable procedure.
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13
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Poschner T, Werner P, Kocher A, Laufer G, Musumeci F, Andreas M, Russo M. The JenaValve pericardial transcatheter aortic valve replacement system to treat aortic valve disease. Future Cardiol 2021; 18:101-113. [PMID: 34647465 DOI: 10.2217/fca-2021-0065] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Transcatheter aortic valve replacement is a valuable alternative technique to surgery and the spectrum of therapy continues to evolve. The JenaValve Pericaridal transcatheter aortic valve replacement System allows prosthesis fixation in a native, noncalcified aortic annulus with a unique paper clip-like anchorage mechanism. The low rate of paravalvular leakage and permanent pacemaker implantation emphasizes the further widespread use of the JenaValve - despite the limited data available. In May 2021, a CE mark for the transfemoral implantation in both aortic regurgitation and aortic stenosis was granted. However, no data have been published so far. The ongoing ALIGN trials are expected to provide the pending long-term data.
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Affiliation(s)
- Thomas Poschner
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Paul Werner
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Alfred Kocher
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Guenther Laufer
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Francesco Musumeci
- Department of Cardiac Surgery & Heart Transplantation, San Camillo Forlanini Hospital of Rome, Rome, Italy
| | - Martin Andreas
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria
| | - Marco Russo
- Department of Cardiac Surgery, Medical University Vienna, Vienna, Austria.,Department of Cardiac Surgery & Heart Transplantation, San Camillo Forlanini Hospital of Rome, Rome, Italy
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14
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Finite element analysis of transcatheter aortic valve implantation: Insights on the modelling of self-expandable devices. J Mech Behav Biomed Mater 2021; 123:104772. [PMID: 34481297 DOI: 10.1016/j.jmbbm.2021.104772] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/29/2021] [Accepted: 08/08/2021] [Indexed: 01/24/2023]
Abstract
Computational simulations of Transcatheter Aortic Valve Implantation (TAVI) have reached a high level of complexity and accuracy for the prediction of possible implantation scenarios during the decision-making process. However, when focusing on the prosthetic device, currently different devices are available on the market which not only have different geometries, but also different material properties. The present work focuses on the calibration of Nitinol constitutive parameters of four self-expandable devices starting from experimental radial force tests on the prosthetic samples. Beside providing optimal material properties for each specific device, we also perform a patient-specific simulation, comparing the results obtained using both "literature" and calibrated parameters with the aim of investigating the impact of metallic frame parameters choice on simulation results.
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15
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Antonini L, Poletti G, Mandelli L, Dubini G, Pennati G, Petrini L. Comprehensive computational analysis of the crimping procedure of PLLA BVS: effects of material viscous-plastic and temperature dependent behavior. J Mech Behav Biomed Mater 2021; 123:104713. [PMID: 34365099 DOI: 10.1016/j.jmbbm.2021.104713] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 10/20/2022]
Abstract
Recently, researchers focused their attention on the use of polymeric bioresorbable vascular scaffolds (BVSs) as alternative to permanent metallic drug-eluting stents (DESs) for the treatment of atherosclerotic coronary arteries. Due to the different mechanical properties, polymeric stents, if compared to DESs, are characterized by larger strut size and specific design. It implies that during the crimping phase, BVSs undergo higher deformation and the packing of the struts, making this process potentially critical for the onset of damage. In this work, a computational study on the crimping procedure of a PLLA stent, inspired by the Absorb GT1 (Abbott Vascular) design, is performed, with the aim of evaluating how different strategies (loading steps, velocities and temperatures) can influence the results in terms of damage risk and final crimped diameter. For these simulations, an elastic-viscous-plastic model was adopted, based on experimental results, obtained from tensile testing of PLLA specimens loaded according to ad hoc experimental protocols. Furthermore, the results of these simulations were compared with those obtained by neglecting strain rate and temperature dependence in the material model (as often done in the literature), showing how this lead to significant differences in the prediction of the crimped diameter and internal stress state.
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Affiliation(s)
- Luca Antonini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Gianluca Poletti
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Lorenzo Mandelli
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Gabriele Dubini
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Giancarlo Pennati
- Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
| | - Lorenza Petrini
- Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
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16
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Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions. Sci Rep 2021; 11:8728. [PMID: 33888765 PMCID: PMC8062511 DOI: 10.1038/s41598-021-87908-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/06/2021] [Indexed: 12/31/2022] Open
Abstract
Left main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.
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17
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Kwiecinski J, Cheng CP, Uberoi R, Hadi M, Hempel P, Degel C, You Z. Thoracic aortic parallel stent-graft behaviour when subjected to radial loading. J Mech Behav Biomed Mater 2021; 118:104407. [PMID: 33740690 DOI: 10.1016/j.jmbbm.2021.104407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 11/20/2020] [Accepted: 02/12/2021] [Indexed: 10/22/2022]
Abstract
To manage complex aortic arch disease using minimally invasive techniques, interventionalists have reported the use of multiple stent-graft devices deployed in a parallel configuration. The structural device-device and device-artery interactions arising during aortic arch parallel endografting, also known as chimney thoracic endovascular aortic repair (ch-TEVAR), is not well understood. Through the use of a radial force testing system we sought to characterise both the loading and deformation behaviour of parallel endografts in representative ch-TEVAR configurations. Four commercially available devices (Bentley BeGraft, Gore TAG, Gore Viabahn, and Medtronic Valiant) were subjected to uniform radial load individually, and in six combinations, to quantify loading profiles. Image data collected during testing were analysed to evaluate mechanical deformations in terms of gutters, chimney and main endograft compression, as well as graft infolding. Parallel endografting was found to increase radial loads when compared to standard TEVAR. Chronic outward force during ch-TEVAR was dependent on main endograft manufacturer, with TAG combinations leading to consistently higher loads than Valiant, but independent of chimney graft type. Endograft deformations were dependent on chimney graft type, with Viabahn combinations presenting with lower gutter areas and increased lumen compression than BeGraft. Chimney graft deformations were also influenced by deployment arrangement in the case of double ch-TEVAR. This study emphasizes the significant variability in both radial loads and mechanical deformations between clinically relevant ch-TEVAR configurations.
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Affiliation(s)
- Jakub Kwiecinski
- Department of Engineering Science, University of Oxford, Oxford, UK.
| | | | - Raman Uberoi
- Department of Vascular Surgery, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Mohammed Hadi
- Department of Vascular Surgery, Oxford University Hospitals NHS Trust, Oxford, UK
| | | | | | - Zhong You
- Department of Engineering Science, University of Oxford, Oxford, UK
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18
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Yeazel TR, Becker ML. Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents. Biomacromolecules 2020; 21:3957-3965. [PMID: 32924443 DOI: 10.1021/acs.biomac.0c01082] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.
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Affiliation(s)
- Taylor R Yeazel
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, United States
| | - Matthew L Becker
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, United States.,Departments of Chemistry, Biomedical Engineering, Orthopaedic Surgery, Duke University, Durham, North Carolina 27708, United States
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19
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Laasch HU, Milward GD, Edwards DW. ‘Radial force’ of colonic stents: A parameter without consistency, definition or standard. INTERNATIONAL JOURNAL OF GASTROINTESTINAL INTERVENTION 2020. [DOI: 10.18528/ijgii200005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Hans-Ulrich Laasch
- Department of Radiology, The Christie NHS Foundation Trust, Manchester, UK
- Department of Natural Sciences, University of Chester, Chester, UK
- Minnova Medical Foundation C.I.C., Wilmslow, UK
| | | | - Derek W. Edwards
- Department of Radiology, The Christie NHS Foundation Trust, Manchester, UK
- Department of Natural Sciences, University of Chester, Chester, UK
- Minnova Medical Foundation C.I.C., Wilmslow, UK
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20
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Jayendiran R, Nour B, Ruimi A. Computational analysis of Nitinol stent-graft for endovascular aortic repair (EVAR) of abdominal aortic aneurysm (AAA): Crimping, sealing and fluid-structure interaction (FSI). Int J Cardiol 2020; 304:164-171. [PMID: 31791620 DOI: 10.1016/j.ijcard.2019.11.091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/20/2019] [Accepted: 11/08/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES We evaluate the crimping strain, sealing stress and contact forces on a Nitinol stent deployed in the aorta during endovascular aortic (or aneurysm) repair (EVAR) procedures. Nitinol shape memory effect (SME) is used. We also study the fluid-structure interaction (FSI) of the blood flow on the stented aorta. METHODS We employ Solidworks to generate a closed-cell honeycomb stent structure used to treat abdominal aortic aneurysm (AAA). We use the commercial Abaqus/Simulia finite element (FEM) simulation package to study the displacements and stresses experienced by the stent during the crimping phase and deployment into the aortic segment. The Nitinol stent is covered with Dacron, a popular graft material. We implement our own user-material (UMAT) subroutines to model the shape memory effect (SME) of Nitinol. The effect of the stent geometry is analyzed. We use the FSI analysis in Abaqus/Simulia to understand the effect of hemodynamic loading on the stent. RESULTS Results indicate that the crimping strain increases as the stent strut spacing increases. This is also the case for the radius of curvature. Maximum strains developed on the stent during crimping are in the order of 10%. Stresses exerted by the stent needed to completely seal the aorta are found to be below the yield stress values of Nitinol (700 MPa). Wall shear stresses (WSS) on the stented aorta are close to WSS obtained on the aorta alone. CONCLUSION Using Nitinol's thermo-reactivity property as opposed to its superelasticity causes the stent-graft to deploy more gently.
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Affiliation(s)
- Raja Jayendiran
- Mechanical Engineering Program, Texas A&M University at Qatar, Doha, Qatar.
| | - Bakr Nour
- Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Annie Ruimi
- Mechanical Engineering Program, Texas A&M University at Qatar, Doha, Qatar.
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21
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Zhang J, Zhou Q, Nelson G. Effect of Continuous Nursing Intervention of Artificial Intelligence on Discharged Patients after Heart Valve Replacement and Application of Omaha System (Preprint). JMIR Med Inform 2020. [DOI: 10.2196/18962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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22
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Alhaizaey A, Aljabri B, Alghamdi M, AlAhmari A, Abulyazied A, Asiry M, Al-Omran M. Delayed Aortic Stent Collapse in Blunt Traumatic Aortic Injury Repair. AORTA : OFFICIAL JOURNAL OF THE AORTIC INSTITUTE AT YALE-NEW HAVEN HOSPITAL 2020; 7:129-136. [PMID: 32018308 PMCID: PMC7000265 DOI: 10.1055/s-0039-3401022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Background
Endovascular stent grafting has emerged as an option to treat traumatic aorta injuries with reported significantly low mortality and morbidity. Stent collapse is one of the complications that can occur in this type of treatment. The aim of this article is to analyze the expected cause of stent collapse and to draw attention to the importance of the surveillance follow-up, as this phenomenon may occur late postdeployment.
Methods
A retrospectively collected dataset from the two highest volume trauma centers in Saudi Arabia was analyzed between April 2007 and October 2012. A total of 66 patients received stent grafts for traumatic aortic injury and were included in the study. We apply Ishimaru's anatomical aortic arch zones and Benjamin's aortic injury grading systems. There were 35 patients with aortic injury at zone 2, 26 patients in zone 3, and 5 patients in zone 4. About 96% (63) of the injuries were grades 2 and 3, including large intimal flap or aortic wall pseudoaneurysm with change in wall contour. The technical success rate, as defined by complete exclusion of lesions without leaks, stroke, arm ischemia or stent-related complications, was 90%.
Results
Proximal stent collapse occurred in 4.5% of patients (3 of 66 inserted stents) during follow-up of 4 to 8 years (mean, 6 years). Patients with stent collapse tended to have an acute aortic arch angle with long-intraluminal stent lip, when compared with patients with noncollapsed stents. Intraluminal lip protrusion more than 10-mm increased collapse (
p
< 0.001). Stent-grafts sizes larger than 28 mm also demonstrated a higher collapse rate (
p
< 0.001).
Conclusions
The risk of stent collapse appears related to poor apposition of the stent due to severe aortic arch angulation in young patients and to large stent sizes (>28 mm). Such age groups may have more anatomical and aortic size changes during the growth. Clinical and radiological surveillance is essential in follow-up after stent-graft treatment for traumatic aortic injury.
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Affiliation(s)
- Abdullah Alhaizaey
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Badr Aljabri
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Musaad Alghamdi
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Ali AlAhmari
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Ahmed Abulyazied
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Mohammed Asiry
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
| | - Mohammed Al-Omran
- Division of Vascular Surgery, King Khalid University, Aseer Central Hospital, Abha, Saudi Arabia
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Wu MCH, Muchowski HM, Johnson EL, Rajanna MR, Hsu MC. Immersogeometric fluid-structure interaction modeling and simulation of transcatheter aortic valve replacement. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2019; 357:112556. [PMID: 32831419 PMCID: PMC7442159 DOI: 10.1016/j.cma.2019.07.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The transcatheter aortic valve replacement (TAVR) has emerged as a minimally invasive alternative to surgical treatments of valvular heart disease. TAVR offers many advantages, however, the safe anchoring of the transcatheter heart valve (THV) in the patients anatomy is key to a successful procedure. In this paper, we develop and apply a novel immersogeometric fluid-structure interaction (FSI) framework for the modeling and simulation of the TAVR procedure to study the anchoring ability of the THV. To account for physiological realism, methods are proposed to model and couple the main components of the system, including the arterial wall, blood flow, valve leaflets, skirt, and frame. The THV is first crimped and deployed into an idealized ascending aorta. During the FSI simulation, the radial outward force and friction force between the aortic wall and the THV frame are examined over the entire cardiac cycle. The ratio between these two forces is computed and compared with the experimentally estimated coefficient of friction to study the likelihood of valve migration.
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Affiliation(s)
- Michael C. H. Wu
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
- School of Engineering, Brown University, 184 Hope Street, Providence, Rhode Island 02912, USA
| | - Heather M. Muchowski
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
- Department of Mathematics, Iowa State University, 396 Carver Hall, Ames, Iowa 50011, USA
| | - Emily L. Johnson
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Manoj R. Rajanna
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, 2043 Black Engineering, Ames, Iowa 50011, USA
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24
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Does clinical data quality affect fluid-structure interaction simulations of patient-specific stenotic aortic valve models? J Biomech 2019; 94:202-210. [DOI: 10.1016/j.jbiomech.2019.07.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/29/2019] [Accepted: 07/31/2019] [Indexed: 11/17/2022]
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25
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Luraghi G, Migliavacca F, García-González A, Chiastra C, Rossi A, Cao D, Stefanini G, Rodriguez Matas JF. On the Modeling of Patient-Specific Transcatheter Aortic Valve Replacement: A Fluid-Structure Interaction Approach. Cardiovasc Eng Technol 2019; 10:437-455. [PMID: 31309527 DOI: 10.1007/s13239-019-00427-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/04/2019] [Indexed: 12/14/2022]
Abstract
PURPOSE Transcatheter aortic valve replacement (TAVR) is a minimally invasive treatment for high-risk patients with aortic diseases. Despite its increasing use, many influential factors are still to be understood and require continuous investigation. The best numerical approach capable of reproducing both the valves mechanics and the hemodynamics is the fluid-structure interaction (FSI) modeling. The aim of this work is the development of a patient-specific FSI methodology able to model the implantation phase as well as the valve working conditions during cardiac cycles. METHODS The patient-specific domain, which included the aortic root, native valve and calcifications, was reconstructed from CT images, while the CAD model of the device, metallic frame and pericardium, was drawn from literature data. Ventricular and aortic pressure waveforms, derived from the patient's data, were used as boundary conditions. The proposed method was applied to two real clinical cases, which presented different outcomes in terms of paravalvular leakage (PVL), the main complication after TAVR. RESULTS The results confirmed the clinical prognosis of mild and moderate PVL with coherent values of regurgitant volume and effective regurgitant orifice area. Moreover, the final release configuration of the device and the velocity field were compared with postoperative CT scans and Doppler traces showing a good qualitative and quantitative matching. CONCLUSION In conclusion, the development of realistic and accurate FSI patient-specific models can be used as a support for clinical decisions before the implantation.
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Affiliation(s)
- Giulia Luraghi
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza L. da Vinci 32, 20133, Milan, Italy.
| | - Francesco Migliavacca
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza L. da Vinci 32, 20133, Milan, Italy
| | - Alberto García-González
- Laboratori de Càlcul Numèric (LaCàN), E.T.S. de Ingenieros de Caminos, Canales y Puertos, Universitat Politècnica de Catalunya (UPC), Jordi Girona 1-3, 08034, Barcelona, Spain
| | - Claudio Chiastra
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza L. da Vinci 32, 20133, Milan, Italy.,PoliToBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
| | - Alexia Rossi
- Department of Biomedical Sciences, Humanitas University, via Rita Levi Montalcini 4, 20090, Pieve Emanuele, MI, Italy
| | - Davide Cao
- Department of Biomedical Sciences, Humanitas University, via Rita Levi Montalcini 4, 20090, Pieve Emanuele, MI, Italy
| | - Giulio Stefanini
- Department of Biomedical Sciences, Humanitas University, via Rita Levi Montalcini 4, 20090, Pieve Emanuele, MI, Italy
| | - Jose Felix Rodriguez Matas
- Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Piazza L. da Vinci 32, 20133, Milan, Italy
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26
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Salemizadeh Parizi F, Mehrabi R, Karamooz-Ravari MR. Finite element analysis of NiTi self-expandable heart valve stent. Proc Inst Mech Eng H 2019; 233:1042-1050. [PMID: 31354047 DOI: 10.1177/0954411919865404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Transcatheter aortic valve implantation is a minimally invasive treatment for severe symptomatic aortic valve stenosis. Nitinol stents are proposed for aortic stenosis patients at high risk. In the present study, at different implantation depths in the aortic valve, the crimping and performance of Nitinol stents are investigated. To do so, a constitutive model based on Microplane theory is utilized and implemented through the finite element to express the constitutive characteristics of Nitinol. The self-expanding stent made of NiTi is designed and simulated using the finite element method. To validate the developed model, the obtained results using beam and solid finite element models are compared with those reported in the literature. Superelastic behavior as well as shape memory effect of the Nitinol stent is studied during crimping and deployment. The simulated results show that the produced radial force increases by increasing the implantation depth in a cardiac cycle.
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Affiliation(s)
| | - Reza Mehrabi
- Department of Mechanical Engineering, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran.,Dynamic and Smart Systems Laboratory, Mechanical, Industrial and Manufacturing Engineering Department (MIME), University of Toledo, Toledo, OH, USA
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Gajewski T, Szajek K, Stȩpak H, Łodygowski T, Oszkinis G. The influence of the nylon balloon stiffness on the efficiency of the intra-aortic balloon occlusion. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019; 35:e3173. [PMID: 30447053 DOI: 10.1002/cnm.3173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 09/10/2018] [Accepted: 11/08/2018] [Indexed: 06/09/2023]
Abstract
In interventional procedures, the balloon inflation is used to occlude the artery and thus reduce bleeding. There is no practically accepted measure of the procedure efficiency. A finite element method model with state-of-the-art modelling techniques was built in order to predict the occlusion levels under the influence of different balloon inflation and its material stiffness. The geometries of a healthy human thoracic aorta and an occlusion balloon were idealized. The non-linear constitutive material of Gasser-Ogden-Holzapfel model was employed for the thoracic aorta; the balloon was model as the hyperelastic model. The realistic physiological blood pressure and the balloon inflation pressures were applied to simulate the different occlusion levels. The final outcome shows an important influence of the material stiffness on the balloon deformation and thus the occlusion efficiency.
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Affiliation(s)
- Tomasz Gajewski
- Institute of Structural Engineering, Poznań University of Technology, Poznań, Poland
| | - Krzysztof Szajek
- Institute of Structural Engineering, Poznań University of Technology, Poznań, Poland
| | - Hubert Stȩpak
- Department of Vascular and Endovascular Surgery, Angiology, and Phlebology, Poznań University of Medical Sciences, Poznań, Poland
| | - Tomasz Łodygowski
- Institute of Structural Engineering, Poznań University of Technology, Poznań, Poland
| | - Grzegorz Oszkinis
- Department of General and Vascular Surgery, Poznań University of Medical Sciences, Poznań, Poland
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Bhogal P, Pederzani G, Grytsan A, Loh Y, Brouwer PA, Andersson T, Gundiah N, Robertson AM, Watton PN, Söderman M. The unexplained success of stentplasty vasospasm treatment : Insights using Mechanistic Mathematical Modeling. Clin Neuroradiol 2019; 29:763-774. [PMID: 30915482 DOI: 10.1007/s00062-019-00776-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 03/08/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cerebral vasospasm (CVS) following subarachnoid hemorrhage occurs in up to 70% of patients. Recently, stents have been used to successfully treat CVS. This implies that the force required to expand spastic vessels and resolve vasospasm is lower than previously thought. OBJECTIVE We develop a mechanistic model of the spastic arterial wall to provide insight into CVS and predict the forces required to treat it. MATERIAL AND METHODS The arterial wall is modelled as a cylindrical membrane using a constrained mixture theory that accounts for the mechanical roles of elastin, collagen and vascular smooth muscle cells (VSMC). We model the pressure diameter curve prior to CVS and predict how it changes following CVS. We propose a stretch-based damage criterion for VSMC and evaluate if several commercially available stents are able to resolve vasospasm. RESULTS The model predicts that dilatation of VSMCs beyond a threshold of mechanical failure is sufficient to resolve CVS without damage to the underlying extracellular matrix. Consistent with recent clinical observations, our model predicts that existing stents have the potential to provide sufficient outward force to successfully treat CVS and that success will be dependent on an appropriate match between stent and vessel. CONCLUSION Mathematical models of CVS can provide insights into biological mechanisms and explore treatment approaches. Improved understanding of the underlying mechanistic processes governing CVS and its mechanical treatment may assist in the development of dedicated stents.
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Affiliation(s)
- P Bhogal
- Department of Interventional Neuroradiology, The Royal London Hospital, Whitechapel Road, E1 1BB, London, UK.
| | - G Pederzani
- Department of Computer Science, University of Sheffield, Sheffield, UK.,Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK
| | - A Grytsan
- Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK
| | - Y Loh
- Uniformed Services University, University of California, Los Angeles, USA.,Swedish Neuroscience Institute, 550 17th Avenue Seattle, 98122, Washington, USA
| | - P A Brouwer
- The Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - T Andersson
- The Karolinska University Hospital, 171 76, Stockholm, Sweden.,AZ Groeninge, Kortrijk, Belgium
| | - Namrata Gundiah
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India
| | - Anne M Robertson
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, USA
| | - Paul N Watton
- Department of Computer Science, University of Sheffield, Sheffield, UK.,Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK.,Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA, USA
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Fretting damage of Ni-rich ultrafine grained NiTi superelastic wires. J Mech Behav Biomed Mater 2018; 90:655-664. [PMID: 30502674 DOI: 10.1016/j.jmbbm.2018.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 10/12/2018] [Accepted: 11/18/2018] [Indexed: 01/16/2023]
Abstract
The effects of fretting on Ni-rich ultra-fine grained NiTi superelastic wires have been characterized. Fretting tests have been performed using wire on wire in 90° cross-cylinder configuration until 105 cycles in air at 25 °C. Constant displacement amplitude of 50 µm and normal loads of 10, 20 and 50 N were considered. For a normal load of 10 N, the tribosystem performed in Gross Slip Regime and the predominance of wear damage was observed. Mixed Fretting Regime was instead observed for normal loads of 20 N and 50 N. In these cases, the predominant damage mechanism was crack formation with the cracks oriented normal to the displacement direction. Occurrence of martensitic transformation in the contact region was inferred from the particular shape of the fretting loops. Due to their possible impact on biocompatibility, the debris detached from the tribosystem during the different experiments were collected and characterized by TEM. They consisted in agglomerations of nano-crystalline TiO2 (rutile) and NiO oxide particles sized between 10 and 20 nm.
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