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Polyurethane heart valve durability: effects of leaflet thickness and material
G M Bernacca1, T G Mackay, M J Gulbransen
1University Department of Cardiac Surgery, Glasgow Royal Infirmary University NHS Trust Scotland, UK.
The International Journal of Artificial Organs
|June 1, 1997
Summary
Polyurethane heart valves with thicker leaflets show improved durability. Polyetherurethaneurea (PEUE) valves, particularly those with median leaflet thickness around 150 microns, exceeded 800 million cycles in fatigue testing, indicating potential for clinical use.
Area of Science:
- Biomaterials Engineering
- Cardiovascular Device Development
- Polymer Science
Background:
- Flexible trileaflet polyurethane valves are fabricated using dip-moulding onto injection-moulded frames.
- Leaflet thickness is a critical factor influencing both valve durability and hydrodynamic function.
Purpose of the Study:
- To investigate the relationship between leaflet thickness and the durability of polyurethane valves.
- To compare the performance of polyetherurethane (PEU) and polyetherurethaneurea (PEUE) leaflets.
Main Methods:
- Fabrication of 31 trileaflet polyurethane valves with varying leaflet thicknesses (60-200 microns).
- Valves were composed of either PEU (n=22) or PEUE (n=9).
- Accelerated fatigue testing at 37°C to monitor failure.
Main Results:
- PEU leaflet thickness did not correlate with durability, with all PEU valves failing before 400 million cycles.
- PEUE valves demonstrated significantly higher durability, exceeding 800 million cycles.
- In PEUE valves, durability showed a strong positive correlation with leaflet thickness (r=0.93, p<0.001), with optimal performance around 150 microns.
Conclusions:
- Polyurethane valves can be engineered for both favorable hydrodynamic properties and enhanced durability.
- PEUE leaflets, specifically with a median thickness of approximately 150 microns, offer promising durability for potential clinical applications.
- Optimizing leaflet thickness is crucial for developing clinically viable polyurethane heart valves.