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Small caliber vascular grafts. Part II: Polyurethanes revisited
1CardioTech International, Inc., Woburn, MA 01801, USA.
Journal of Biomaterials Applications
|July 1, 1996
Summary
Polyurethanes offer excellent biocompatibility for small caliber vascular grafts, with advancements in material stability and processing technologies enhancing their performance and healing potential. Further modifications are needed to maximize biodurability for broader clinical applications.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Biomedical Engineering
Background:
- Polyurethanes are highly bio- and blood-compatible polymers extensively used in biomedical applications.
- Their structure-property relationships allow for the development of materials mimicking natural tissue mechanics.
- Polyurethanes have been crucial in advancing small-caliber vascular graft technology for various bypass indications.
Purpose of the Study:
- To review the achievements and discuss trends in polyurethane-based vascular graft development.
- To explore how material modifications influence graft properties like durability, elasticity, and healing.
- To identify future directions for enhancing polyurethane biodurability for improved graft performance.
Main Methods:
- Intelligent utilization of structure/property relationships in polyurethane synthesis.
- Surface and bulk modifications with biologically active agents (e.g., anticoagulants, anti-infectives).
- Fabrication techniques including casting, spinning, extrusion, dip coating, and spraying, coupled with phase inversion.
Main Results:
- Early polyurethanes (polyester-based) showed hydrolytic instability; polyether-based versions offered improvements but faced oxidative sensitivity and in vivo instability.
- Polycarbonate polyols represent a significant advancement, yielding hydrolytically and oxidatively stable materials with improved biodurability.
- Various processing technologies enable the creation of porous, multilayered conduits with desirable vascular graft characteristics.
Conclusions:
- Polyurethanes have evolved significantly, with polycarbonate-based materials showing promise for vascular access and peripheral grafts.
- Further research into modifying both soft and hard segments is essential to maximize biodurability for patent small-caliber grafts.
- Continued innovation in material design and processing holds potential for realizing the full capabilities of polyurethanes in vascular device development.