Early wear development in a novel mechanical heart valve prosthesis made from polymeric materials

Abstract

Background and aim of the study: Currently, 95% of all implanted mechanical heart valve prostheses are constructed completely, or at least partially, from pyrolytic carbon. In order to develop a mechanical heart valve prosthesis made from alternative materials, a special hinge design was tested which enabled the integration of wear-resistant tribomaterials into the highly loaded hinges of leaflets.

Methods: The wear behavior of different material couples was investigated in vitro. Wear testing was performed using a specially designed durability tester that controlled the pressure difference across the closed heart valve prosthesis in a water-glycerol mixture with blood analog viscosity. Conditions were set according to FDA and ISO standards for heart valve testing. Qualitative assessment of wear behavior was performed using light microscopy and scanning electron microscopy at intervals of 10, 40, and each subsequent 50 million cycles.

Results: None of the investigated heart valve prostheses failed during the durability tests. Compared to the reference valve made from polymeric materials, wear especially in the hinges could be reduced to an acceptable level by integrating wear-resistant tribomaterials into the leaflets.

Conclusion: A leaflet design which enables the integration of tribomaterials into the highly loaded hinges of leaflets leads to an optimization of wear behavior of a mechanical heart valve prosthesis made from polymeric materials. Abrasive wear in the hinges may be reduced to an acceptable level for the functionality of the heart valve prosthesis. Durability tests will be continued in order to confirm the promising wear behavior of this novel heart valve prosthesis.