Abstract 16952: Stent Geometry and Radial Force Comparison of Portico vs CoreValve
Background: Nitinol is a stent frame material used in self-expandable valves for transcatheter aortic valve replacement (TAVR). The design & processing of nitinol affects stent radial forces, and thus performance of such TAVR technologies. In this study, a comparison of stent frame geometry and radial force is done for Portico (St Jude Medical, St Paul MN) vs. CoreValve (CV) (Medtronic, Minneapolis MN).
Methods: Three CVs (2 [[Unable to Display Character: –]] 26mm & 1 [[Unable to Display Character: –]] 29mm valve) were characterized & compared to Portico (2 ea. of 23/25/27/29mm). To compare geometry, a micro-CT scan of CV frame was obtained, and a STL model was generated in SolidWorks. The valves were then loaded into its delivery system per IFU & deployed into a radial force tester (Machine Solutions Inc (MSI), AZ). The MSI was cycled from stent parent diameter to the catheter diameter (5mm) & back to obtain radial forces.
Results: Portico stent has 36 cells whereas CV has 135 cells. The open cell design allows a larger catheter (15F) to access coronaries in an implanted Portico as compared to 12F for CV. Mathematical analysis shows that CV has 36% higher surface area (minimum) as compared to Portico stent.
The radial force exerted by CV at 5mm is at least 2X times that of Portico. In addition, CV has a larger hysteresis loop from compression to expansion [[Unable to Display Character: –]] thus more energy is needed to compress CV into a catheter. Within its use range, Portico has a uniform hoop force as compared to CV (Figure). This enables Portico valve handling to be similar across its sizes.
Conclusions: The Portico stent frame has lower cell density & surface area as compared to CV. In conjunction with placement strategy, this potentially translates to lower clinical incidences of conduction disturbance. The radial forces of Portico allow resheathability, providing a physician with more placement control. Uniform radial force within use range should promote better apposition, anchoring and sealing of the Portico valve. The implication should be further characterized in a clinical setting.
Author Disclosures: S. Kumar: None. B. Moseman: None. K. Vietmeier: None.
- © 2014 by American Heart Association, Inc.