A self-expandable nitinol frame for cable-driven parallel mechanisms in minimally invasive cardiovascular interventions.

Abstract

The integration of self-expandable nitinol frames with cable-driven parallel mechanisms offers a promising advancement in minimally invasive cardiovascular interventions. This study presents the design, fabrication, and verification of a miniaturized self-expandable nitinol frame to enhance catheter tip steerability and navigation within complex vascular anatomies. The frame is reduced in size for delivery through 7-8 Fr sheaths while accommodating diverse vascular diameters, allowing up to a maximum expansion of 15 mm. Iterative design and parametric studies ensured robust vessel anchoring with minimal deflection to maintain catheter tip control accuracy. Extensive testing included finite element simulations and benchtop experiments. Crimping simulations confirmed that the maximum Von Mises stresses (575 MPa) did not exceed nitinol's yield stress, and deformation profiles matched experimental results. Deflection tests showed minimal deflections below 0.45 mm at the frame's anchoring points, ensuring precise tip control. Radial force studies validated balanced forces below 6 N (for target vessel diameters), preventing migration without damaging vessel walls. Friction studies demonstrated superior performance, reducing friction and enhancing force transmission efficiency. These findings indicated that the proposed miniaturized frame design is a feasible option for cardiovascular interventions.