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Mechanical and morphological study of biostable polyurethane heart valve leaflets explanted from sheep
Gillian M Bernacca1, Ian Straub, David J Wheatley
1University Department of Cardiac Surgery, Royal Infirmary, 10 Alexandra Parade, Glasgow G31 2ER, United Kingdom. g.bernacca@clinmed.gla.ac.uk
Journal of Biomedical Materials Research
|May 10, 2002
Summary
Novel polyurethanes for heart valves showed no biodegradation after 9 months in sheep. Material analysis and mechanical testing confirmed biostability, indicating potential for durable medical devices.
Area of Science:
- Biomaterials Science
- Polymer Chemistry
- Cardiovascular Engineering
Background:
- Development of biostable materials is crucial for long-term performance of artificial heart valves.
- Siloxane-based polyurethanes offer potential for cardiovascular applications due to their inherent flexibility and biocompatibility.
Purpose of the Study:
- To evaluate the in vivo biostability and mechanical integrity of two novel polyurethanes (EV3.34 and EV3.35) in a sheep mitral heart valve model.
- To assess potential degradation and changes in material properties after implantation.
Main Methods:
- Flexible trileaflet heart valves manufactured from EV3.34 and EV3.35 polyurethanes were implanted in the mitral position of sheep.
- Explanted valves at 6 and 9 months were analyzed using Attenuated Total Reflectance Fourier Transform Infrared Spectrometry (ATR/FTIR) and Scanning Electron Microscopy (SEM).
- Cyclic mechanical testing was performed on explanted leaflet material to assess changes in mechanical properties.
Main Results:
- ATR/FTIR analysis revealed no degradation of functional groups, with a slight surface enrichment of siloxane soft segment observed.
- SEM showed similar surface morphology between explanted and control leaflet materials.
- EV3.34 maintained similar inelastic energy loss and residual strain, while EV3.35 showed a reduction in these mechanical properties.
Conclusions:
- The siloxane-based polyurethanes EV3.34 and EV3.35 demonstrate no evidence of biodegradation after 9 months of implantation in functional heart valves in a sheep model.
- The retention of mechanical properties, supported by FTIR and SEM findings, suggests the potential suitability of these materials for cardiovascular applications.