Novel airway stent using a thermal shape-memory Ti-Ni alloy

Area of Science:

• Biomedical Engineering
• Materials Science
• Veterinary Medicine

Background:

• Tracheomalacia and bronchomalacia pose significant clinical challenges.
• Current treatment options for airway collapse often involve invasive surgical procedures.
• Nonsurgical interventions are needed for effective airway support.

Purpose of the Study:

• To develop and evaluate a novel tracheal or bronchial stent for nonsurgical implantation.
• To assess the feasibility of using a nickel-titanium shape-memory alloy for airway stenting.
• To investigate the biocompatibility and retention of the stent in a canine model.

Main Methods:

• A tracheal stent was fabricated from a 50% nickel-titanium alloy with a transition temperature of 20°C.
• The stent was designed with a horseshoe cross-section and delivered via bronchoscope after cooling.
• A tracheomalacia model was created in 10 dogs, and stents were implanted and explanted at intervals from 1 week to 6 months for examination.

Main Results:

• Nine out of ten implanted stents were found in the target tracheal region; one stent displaced to the bifurcation.
• Microscopic examination revealed gradual epithelial coverage of the stent wires over time.
• At 6 months post-implantation, 58% of the stent surface area was covered by epithelium.

Conclusions:

• Nickel-titanium alloy stents are a viable option for nonsurgical airway support.
• The shape-memory properties of the alloy facilitate minimally invasive implantation.
• The stent demonstrates good biocompatibility and tissue integration in a canine tracheomalacia model.