Pure pyrolytic carbon: preparation and properties of a new material, On-X carbon for mechanical heart valve prostheses
Ely, J.L.; Emken, M.R.; Accuntius, J.A.; Wilde, D.S.; Haubold, A.D.; More, R.B.; Bokros, J.C.
Journal of Heart Valve Disease 7(6): 626-632
1998
ISSN/ISBN: 0966-8519 PMID: 9870196 Document Number: 489637
Historically, the pyrolytic carbon used in mechanical prosthetic heart valves contained small amounts of silicon, this being a necessary additive to achieve consistently the hardness required for wear resistance. New processing technology has allowed the deposition of pyrolytic carbon without silicon, while maintaining adequate hardness to ensure wear resistance. A parametric study of coating parameters identified the conditions necessary to produce the optimal pure carbon material. In comparison with silicon-alloyed carbon, the pure carbon was found to be about 20% stronger, have a strain-to-failure about 25% higher and have a greater toughness. The enhanced strength, deformability and toughness of the new carbon permits designers to utilize component shapes and dimensions that could not be manufactured using the silicon-alloyed carbons. Such design features have hemodynamic benefits resulting in valve performance improvements.