Pure pyrolytic carbon: preparation and properties of a new material, On-X carbon for mechanical heart valve prostheses.
OBJECTIVE
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.


METHODS
A parametric study of coating parameters identified the conditions necessary to produce the optimal pure carbon material.


RESULTS
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.


CONCLUSIONS
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.
Ely
J L
JL
Medical Carbon Research Institute, Austin, Texas 78754, USA.
Emken
M R
MR
Accuntius
J A
JA
Wilde
D S
DS
Haubold
A D
AD
More
R B
RB
Bokros
J C
JC
D002244:Carbon; D006350:Heart Valve Prosthesis; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design
D002244:Carbon