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Rofo 2014; 186(2): 157-165
DOI: 10.1055/s-0033-1350439
Experimentelle Radiologie
© Georg Thieme Verlag KG Stuttgart · New York

Experimental Investigation of Modern and Established Carotid Stents

Experimentelle Untersuchung von modernen und etablierten Carotis-Stents
C. Wissgott
1   Institute of Diagnostic and Interventional Radiology/Neuroradiology, Westkuestenklinikum Heide – Academic Teaching Hospital of the Universities of Kiel, Luebeck and Hamburg, Heide
,
W. Schmidt
2   Institute for Biomedical Engineering, University of Rostock, Rostock-Warnemünde
,
P. Behrens
2   Institute for Biomedical Engineering, University of Rostock, Rostock-Warnemünde
,
C. Brandt
2   Institute for Biomedical Engineering, University of Rostock, Rostock-Warnemünde
,
K. P. Schmitz
2   Institute for Biomedical Engineering, University of Rostock, Rostock-Warnemünde
,
R. Andresen
1   Institute of Diagnostic and Interventional Radiology/Neuroradiology, Westkuestenklinikum Heide – Academic Teaching Hospital of the Universities of Kiel, Luebeck and Hamburg, Heide
› Author Affiliations
Further Information

Publication History

18 April 2013

16 July 2013

Publication Date:
30 August 2013 (online)

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Abstract

Purpose: The design and material determine the mechanical properties of stents. In vitro parameters such as radial force, flexibility and wall adaptation of different stents were investigated in order to obtain evidence for clinical use.

Materials and Methods: A total of 8 stents, including 2 hybrid stents with a combination of closed/open-cell design (Sinus Carotid RX, Cristallo Ideale), 3 closed-cell stents (Adapt, Carotid Wallstent, Xact Carotid) and 3 open-cell stents (Vivexx Carotid, Protégé Rx and Precise) with a diameter of 8 mm and a length of 40 mm, were investigated. The radial force, the bending stiffness of the stent system and of the stent, and the collapse pressure were measured. The wall adjustment of the stents was documented by fluoroscopy and assessed in a step and curve model.

Results: The bending stiffness of the stent systems declined significantly in the expanded state, whereby the Xact Carotid stent showed the highest value (291.1 N/mm2) in contrast to 31.6–39.4 N/mm2 for the Sinus Carotid and Cristallo Ideale. The radial force on expansion of the stents to 7 mm was lowest for the Adapt (0.009 N/mm) and highest for the Precise (0.068 N/mm). The collapse pressure was highest for the Carotid Wallstent (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 the Cristallo Ideale and the Carotid Wallstent. The Adapt showed poor vessel wall adaptation in both step and curved vessels.

Conclusion: As a result of their design, the Sinus Carotid Rx and the Cristallo Ideale show the best wall adjustment, with comparable radial force and high flexibility, whereby the Cristallo Ideale has the advantage that it has a closed-cell design in the middle third of the stent. The other stents should be taken into consideration with their specifications in individual cases.

Key Points: The investigation of carotid stents provides an objective comparison of mechanical properties. Conclusions about the respective optimum uses of stents can be drawn from this. The hybrid stents show a good balance of properties for wide applicability.

Citation Format:

• Wissgott C, Schmidt W, Behrens P et al. Experimental Investigation of Modern and Established Carotid Stents. Fortschr Röntgenstr 2014; 186: 157 – 165

Zusammenfassung

Ziel: Design und Material bestimmen die mechanischen Eigenschaften von Stents. In vitro Kennwerte wie Radialkraft, Flexibilität und Wandanpassung unterschiedlicher Stents wurden untersucht, um Hinweise für den klinischen Einsatz zu bekommen.

Material und Methoden: Es wurden 8 Stents, hiervon 2 Hybrid-Stents mit einer Kombination von closed-/open-cell-design (Sinus Carotid RX, Cristallo Ideale), 3 closed-cell-Stents (Adapt, Carotid Wallstent, Xact Carotid) und 3 open-cell-Stents (Vivexx Carotid, Protégé Rx und Precise) mit einem Durchmesser von 8 mm bei einer Länge von 40 mm, untersucht. Gemessen wurden die Radialkraft, die Biegesteifigkeit des Stentsystems und des Stents sowie der Kollapsdruck. Die Wandanpassung der Stents wurde in einem Stufen- und Kurvenmodell fluoroskopisch dokumentiert und beurteilt.

Ergebnisse: Die Biegesteifigkeit der expandierten Stents war deutlich geringer als die der Stentsysteme, wobei der Xact Carotid Stent den höchsten Wert (291,1 N/mm2) aufwies im Gegensatz zu 31,6 bis 39,4 N/mm2 für den Sinus Carotid und Cristallo Ideale. Die längenbezogene Radialkraft bei Expansion der Stents auf 7 mm war beim Adapt (0,009 N/mm) am niedrigsten und beim Precise (0,068 N/mm) am höchsten. Der Kollapsdruck ist beim Carotid Wallstent am höchsten (0,48 bar) im Vergleich zu den übrigen Stents (0,1 – 0,2 bar). Die beste Wandanpassung im Kurvenmodell zeigten der Precise, der Sinus Carotid Rx und der Vivexx Carotid Stent. Der Durchmessersprung von 5 auf 7 mm im Stufenmodell wurde am besten vom Cristallo Ideale und dem Carotid Wall Stent überwunden. Der Adapt zeigt in beiden Modellen die schlechteste Wandanpassung.

Schlussfolgerung: Designbedingt zeigen der Sinus Carotid Rx und der Cristallo Ideale die beste Wandanpassung bei vergleichbarer Radialkraft und hoher Flexibilität, wobei der Cristallo Ideale den Vorteil hat, dass er über ein closed-cell-Design im mittleren Stentdrittel verfügt. Die übrigen Stents sind im Einzelfall weiterhin zu berücksichtigen.

Kernaussagen: Die Untersuchung der Carotis-Stents liefert eine objektive Vergleichbarkeit der mechanischischen Eigenschaften. Hieraus können Schlussfolgerungen über die jeweilige optimale Einsatzmöglichkeiten der Stents gezogen werden. Die Hybrid-Stents zeigen dabei ausgewogene Eigenschaften für eine breite Anwendungsmöglichkeit.

Key words

carotid arteries - interventional procedures - stents - experimental study
 

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