• Vaughan, Ted J.
• Gries, Thomas
• Ronan, William
• Lucchetti, Agnese
• Bernini, Martina
• Mckenna, Ciara G.
• Hellmuth, Rudolf
• Dunlop, Craig
• Osullivan, Mike

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose</jats:title><jats:p>Altered hemodynamics caused by the presence of an endovascular device may undermine the success of peripheral stenting procedures. Flow-enhanced stent designs are under investigation to recover physiological blood flow patterns in the treated artery and reduce long-term complications. However, flow-enhanced designs require the development of customised manufacturing processes that consider the complex behaviour of Nickel-Titanium (Ni-Ti). While the manufacturing routes of traditional self-expanding Ni–Ti stents are well-established, the process to introduce alternative stent designs is rarely reported in the literature, with much of this information (especially related to shape-setting step) being commercially sensitive and not reaching the public domain, as yet.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>A reliable manufacturing method was developed and improved to induce a helical ridge onto laser-cut and wire-braided Nickel–Titanium self-expanding stents. The process consisted of fastening the stent into a custom-built fixture that provided the helical shape, which was followed by a shape-setting in air furnace and rapid quenching in cold water. The parameters employed for the shape-setting in air furnace were thoroughly explored, and their effects assessed in terms of the mechanical performance of the device, material transformation temperatures and surface finishing.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Both stents were successfully imparted with a helical ridge and the optimal heat treatment parameters combination was found. The settings of 500 °C/30 min provided mechanical properties comparable with the original design, and transformation temperatures suitable for stenting applications (<jats:italic>A</jats:italic><jats:sub>f</jats:sub> = 23.5 °C). Microscopy analysis confirmed that the manufacturing process did not alter the surface finishing. Deliverability testing showed the helical device could be loaded onto a catheter delivery system and deployed with full recovery of the expanded helical configuration.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>This demonstrates the feasibility of an additional heat treatment regime to allow for helical shape-setting of laser-cut and wire-braided devices that may be applied to further designs.</jats:p></jats:sec>

Topics

• impedance spectroscopy
• surface
• nickel
• titanium
• size-exclusion chromatography
• wire
• quenching
• microscopy