Use of Circular Foldable Nitinol Blades for Resecting Calcified Aortic Heart Valves

• Published in: Journal of materials engineering and performance 2009-08, Vol.18 (5-6), p.463-469
• Main Authors: Hauck, Florian, Wendt, Daniel, Stühle, Sebastian, Kawa, Emilia, Wendt, Hermann, Müller, Wiebke, Thielmann, Matthias, Kipfmüller, Brigitte, Vogel, Bernd, Jakob, Heinz
• Format: Article
• Language: English
• Subjects: Blades (cutting); Characterization and Evaluation of Materials; Corrosion and Coatings; Cutting; Engineering Design; Heart valves; Intermetallics; Materials Science; Nickel titanides; Quality Control; Reliability; Safety and Risk; Shape memory alloys; Tribology; Valve leaflets; Valves
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-009-9436-4

The use of percutaneous aortic valve implantation is limited, as the native calcified valve is left in situ. A new device has been developed for resecting calcified aortic valves, using collapsible nickel-titanium blades: laser-cut T-structures of Nitinol sheet-material (Ni51Ti49 at.%) have been grinded on a high-speed milling cutter to produce cutting edges which have been given the shape of half-circles afterwards. These have been connected to each other and to struts by using rivets which also serve as articulating axes for the cutting ring. The blades are folded around these axes and retreated into a tube to be inserted in the heart through the calcified valve leaflets. Once released, the cutting edges regain their ring-shape. By combining rotation of the ring with a translating movement against a second ring of slightly greater diameter on the instrument, a punching process is created which cuts the calcified valve leaflets and leaves a circular annulus, where a prosthesis can be fixed. In vitro cutting of artificially calcified valves ( n  = 6) resulted in a resection time of t  = 22 ± 6.29 s with a maximum turning moment of M  = 2.4 ± 1.27 Nm, proving the function and the feasibility of the concept.