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Evaluation of disc retention of Björk-Shiley Delrin heart valves
K Thyagarajan1, C H Conlin, D W Wieting
1Shiley Heart Valve Research Center, Irvine, CA 92714, USA.
Background And Aims Of The Study:
Impact wear grooves have been observed in the occluder discs of clinically explanted Björk-Shiley Delrin (BSD) heart valves due to repetitive closing impacts against the inlet strut. We examined whether this impact wear could increase the disc-to-strut gap, which could in turn affect the retention of occluder disc.
Materials And Methods:
Three BSD heart valves with deep wear grooves were tested in a left ventricular assist device set-up simulating dynamic conditions that would facilitate the dislodgement.
Results:
The disc was found to be rotating within the flange during the testing and no embolization of the occluder disc occurred in any of the BSD valves tested. The Björk retention limit and the physical retention limit were calculated for each valve. The Björk retention limit is defined as (disc well depth)-(disc-to strut gap)-(1/2 outlet strut wire diameter) and the physical retention as (disc well depth)-(disc-to strut gap).
Conclusion:
The disc retention would not be affected by the impact wear grooves as long as the disc-to-strut gap did not exceed the physical retention limit.