Advancing neurovascular treatment: FeMnN—Mo composite wires for absorbable flow Diverters

Mon, 06 Feb 2023 14:35:00 Z

The growing demand for innovative solutions to treat intracranial aneurysms has driven advancements in medical materials. Researchers at Fort Wayne Metals have developed FeMnN-Mo composite wires as a foundation for absorbable flow diverters. These devices, designed to treat aneurysms by redirecting blood flow and promoting clot formation, are expected to dissolve after achieving their purpose, reducing long-term complications.

Challenges with existing materialsExisting flow diverters employ permanent metals such as 35N LT® or Nitinol. These devices function well but are unnecessary after aneurysm occlusion and can impede secondary procedures. Absorbable polymers like polyglycolic acid (PGA) and poly-l-lactic acid (PLLA) have been investigated as temporary options but require larger struts for sufficient strength, compromising device profile and flexibility. Absorbable Mg- and Fe-based devices have also been investigated but suffer from rapid degradation and premature fracture.

Innovative FeMnN-Mo composite wiresThe study introduces composite DFT® wires made of:

FeMnN shell: Provides strength, elasticity, and a cell-friendly surface.
Molybdenum (Mo) core: Offers enhanced radiopacity and staged corrosion protection.

These wires, available in diameters as fine as 25 µm, mimic the dimensions of traditional metallic flow diverters while addressing their limitations.

Key findings

Mechanical performance

The composite wires achieved mechanical properties comparable to non-absorbable counterparts, with customizable strength and elasticity by varying Mo content.
Braided prototypes demonstrated crush resistance similar to commercial devices, making them suitable for neurovascular applications.

Enhanced radiopacity

The Mo core significantly improved visibility under fluoroscopic guidance, essential for precise device placement.
Radiopacity increased proportionally with Mo content, ensuring adequate imaging performance without permanent markers.

Corrosion Behavior

In vitro and in vivo tests showed progressive and controlled degradation of the FeMnN shell, while the Mo core remained intact for at least six months.
This staged degradation minimizes the risk of premature fragmentation.

Biocompatibility

Cytotoxicity testing confirmed minimal impact on cellular health, supporting the material's safety for clinical use.

Advantages for Neurovascular Devices

Minimized profile: Comparable to traditional flow diverters, enabling easier navigation in small vessels.
Reduced long-term risks: Absorbability eliminates concerns like chronic inflammation, side branch blockage, and imaging artifacts from permanent implants.
Improved healing: Supports endothelial tissue regeneration over aneurysm necks for effective occlusion.

Future Directions
While these findings highlight the potential of FeMnN-Mo DFT® composite wires, further research is needed to optimize their degradation timeline and assess long-term clinical performance. Exploring additional configurations and alloy combinations could further enhance their functionality.

Conclusion
FeMnN-Mo DFT® composite wires represent a promising step forward in the development of absorbable flow diverters. By addressing critical challenges in material performance and compatibility, this innovation paves the way for safer and more effective neurovascular treatments.

Fort Wayne Metals - Technical Blog

Advancing neurovascular treatment: FeMnN—Mo composite wires for absorbable flow Diverters