Objective The design and material determine the mechanical properties of stents and implant behaviour during the intervention. In vitro parameters such as radial force, flexibility and wall adaptation of different stents were investigated in order to obtain evidence for clinical use.
Material and Methods A total of 8 current stent systems (Sinus Carotid RX, Cristallo Ideale, Adapt, Carotid Wallstent, Vivexx Carotid Stent, Xact Carotid Stent, Protégé Rx and Precise) with a diameter of 8 mm and a length of 40 mm, which are authorised for the treatment of carotid stenoses, were investigated. The radial force on expansion as a function of the diameter, the flexural rigidity of the stent system and of the stent in its expanded state, as well as the collapse pressure in a thin, flexible sleeve were measured. The wall adjustment of the expanded stents was documented by fluoroscopy after release in a step and curve model and assessed.
Results The flexural rigidity of the stent systems declined significantly in the expanded state, whereby the Xact Carotid stent showed the highest value (291.1 Nmm2) in contrast to 31.6 to 39.0 Nmm2 for the Sinus Carotid and Cristallo Ideale. The radial force on expansion of the stents to 7 mm was lowest in the Adapt (0.009 N/mm) and highest in the Precise (0.068 N/mm), while the hybrid stents achieved values of between 0.027 and 0.046 N/mm. The collapse pressure was highest in the Carotid Wallstent as a result of its particular stent structure (0.48 bar), compared with the other stents (0.1 - 0.2 bar). The best wall adjustment in the curve model was shown by the Precise, the Sinus Carotid Rx and the Vivexx Carotid Stent. The diameter change from 5 to 7 mm was smoothly adapted by Cristallo Ideale and Carotid Wall Stent. The extraordinary design of the Adapt showed poor vessel wall adaptation both in step and curved vessels.
Conclusion As a result of their design, the Sinus Carotid Rx and the Cristallo Ideale in the “hybrid design” show the best wall adjustment, with comparable radial force and high flexibility, and thus can also be used in the case of an axis-deviant vascular course with variations in vessel diameter, whereby the Cristallo Ideale has the advantage that it has a “closed-cell” design in the middle third of the stent. In the event of unusual vascular anatomies, the other stents should be taken into consideration with their specifications in individual cases.
Disclosures C. Wissgott: None. W. Schmidt: None. P. Behrens: None. K. Schmitz: None. R. Andresen: None.
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