Multi-scale mechanical investigation of stainless steel and cobalt–chromium stents

Kapnisis, Konstantinos; Constantinides, Georgios; Georgiou, Harry M.; Cristea, Daniel; Gabor, Camelia; Munteanu, Daniel; Brott, Brigitta C.; Anderson, Peter G.; Lemons, Jack E.

doi:10.1016/j.jmbbm.2014.09.010

Cited by 42 publications

(34 citation statements)

References 51 publications

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“…Therefore, the potential risk of fracture can be classified as low. This estimation is in good agreement with the results of Kapnisis [15]. He compared stainless steel and CoCr stents with similar geometry with regard to their fracture behavior after 100 million load cycles.…”

Section: Resultssupporting

confidence: 89%

“…As available from the extended areas of green and yellow colors in the stent bow and in contrast to that predominantly blue coloring in the stent strut the much lower deformation in the strut than in the bow becomes obvious. This is in good agreement with the locations of high misorientations corresponding to high plastic deformation as well as high hardness measured by Kapnisis [15]. In his investigations of the hardness by means of nanoindentation he identified regions of high hardness in the stent bows and correlated them to high plastic deformation.…”

Section: Resultssupporting

confidence: 87%

“…They could identify regions of high hardness and related them to the gradient of plastic strains generated during the deployment process and the associated stress. These regions were correlated with the locations where macroscopic fractures have been observed in both mechanically tested and human explanted stents because of a reduction in plastic work ratio [15]. …”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs

Weiß

Mitevski

2015

Materials

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Coronary heart disease is still one of the most common sources for death in western industrial countries. Since 1986, a metal vessel scaffold (stent) has been inserted to prevent the vessel wall from collapsing. Most of these coronary stents are made from CrNiMosteel (316L). Due to its austenitic structure, the material shows a good combination of strength, ductility, corrosion resistance, and biocompatibility. However, this material has some disadvantages like its non-MRI compatibility and its poor fluoroscopic visibility. Other typically used materials are the CoBase alloys L-605 and F-562 which are MRI compatible as well as radiopaque. Another interesting fact is their excellent radial strength and therefore the ability to produce extra thin struts with increased strength. However, because of a strut diameter much less than 100 μm, the cross section consists of about 5 to 10 crystal grains (oligocrystalline). Thus, very few or even just one grain can be responsible for the success or failure of the whole stent. To investigate the relation between microstructure, mechanical factors and stent design, commercially available Cobalt-Chromium stents were investigated with focus on distinct inhomogeneous plastic deformation due to crimping and dilation. A characteristic, material related deformation behavior with predominantly primary slip was identified to be responsible for the special properties of CoCr stents.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs

Weiß

Mitevski

2015

Materials

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“…Nanometer‐thick regions of oxides are lost under complex in vivo conditions, such as vessel tortuosity, high curvature, vascular wall stresses as well as blood flow wall shear stresses and diffuse calcification . These conditions may compound their effects when two or more overlapping stents are deployed, a common clinical practice in interventional procedures especially in areas of branches and bifurcations or when treating long or recurrent lesions.…”

Section: Discussionmentioning

confidence: 99%

In vivo monitoring of the inflammatory response in a stented mouse aorta model

Kapnisis

Pitsillides

Prokopi³

et al. 2015

J Biomedical Materials Res

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The popularity of vascular stents continues to increase for a variety of applications, including coronary, lower limb, renal, carotid, and neurovascular disorders. However, their clinical effectiveness is hindered by numerous postdeployment complications, which may stimulate inflammatory and fibrotic reactions. The purpose of this study was to evaluate the vessel inflammatory response via in vivo imaging in a mouse stent implantation model. Corroded and noncorroded self-expanding miniature nitinol stents were implanted in mice abdominal aortas, and novel in vivo imaging techniques were used to assess trafficking and accumulation of fluorescent donor monocytes as well as cellular proliferation at the implantation site. Monocytes were quantitatively tracked in vivo and found to rapidly clear from circulation within hours after injection. Differences were found between the test groups with respect to the numbers of recruited monocytes and the intensity of the resulting fluorescent signal. Image analysis also revealed a subtle increase in matrix metalloproteinase activity in corroded compared with the normal stented aortas. In conclusion, this study has been successful in developing a murine stent inflammation model and applying novel in vivo imaging tools and methods to monitor the complex biological processes of the host vascular wall response.

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“…48,53 Such zones are the most vulnerable to the risk of long-term fatigue failure and they present the highest fatigue indicator factors (see Figs. 7 and 8).…”

Section: Numerical Evidencementioning

confidence: 99%

Fatigue of Metallic Stents: From Clinical Evidence to Computational Analysis

et al. 2015

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The great success of stents in treating cardiovascular disease is actually undermined by their long-term fatigue failure. The high variability of stent failure incidence suggests that it is due to several correlated aspects, such as loading conditions, material properties, component design, surgical procedure, and patient functional anatomy. Numerical and experimental non-clinical assessments are included in the recommendations and requirements of several regulatory bodies and they are thus exploited in the analysis of stent fatigue performance. Optimization-based simulation methodologies have been developed as well, to improve the fatigue endurance of novel designs. This paper presents a review on the fatigue issue in metallic stents, starting from a description of clinical evidence about stent fracture up to the analysis of computational approaches available from the literature. The reported discussion on both the experimental and numerical framework aims at providing a general insight into stent lifetime prediction as well as at understanding the factors which affect stent fatigue performance for the design of novel components.

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Multi-scale mechanical investigation of stainless steel and cobalt–chromium stents

Cited by 42 publications

References 51 publications

Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs

Microstructure and Deformation of Coronary Stents from CoCr-Alloys with Different Designs

In vivo monitoring of the inflammatory response in a stented mouse aorta model

Fatigue of Metallic Stents: From Clinical Evidence to Computational Analysis

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