Lh. Leuer et al., MATERIAL PROPERTIES, BIOCOMPATIBILITY, AND WEAR-RESISTANCE OF THE MEDTRONIC PYROLYTIC CARBON, Journal of heart valve disease, 5, 1996, pp. 105-109
Pyrolytic carbon is the material of-choice for components in the major
ity of heart valves available today. Many manufacturers have verticall
y integrated their manufacturing capabilities to include their own car
bon manufacturing facilities. Medtronic is no exception. Because of th
e critical nature of pyrolytic carbon to the success of a valve design
, a series of in vitro tests were conducted to determine the relative
equivalence of Medtronic and CarboMedics, Inc. (CMI) pyrolytic carbon
based on the Medtronic Hall(TM) design. Correlation between in vivo an
d in vitro pyrolytic carbon wear is provided based on an analysis of e
xplanted Medtronic Hall discs manufactured by CMI. Material, physical,
chemical, and biocompatibility proprieties for Medtronic carbon were
determined using standardized techniques. Structural integrity of the
discs was evaluated by accelerated cyclic testing to determine depth o
f wear characteristics. Explanted valves were subjected to identical d
epth of wear analysis. No statistical difference was found between CMI
and Medtronic pyrolytic carbon discs based on mechanical and physical
properties and depth of wear on both inflow and outflow disc surfaces
. Furthermore, evaluation of CMI discs after explant from human subjec
ts confirms similar wear characteristics with a half life in excess of
the 570 years projected from the in vitro experiments. In summary, ma
terial properties, structural integrity and biocompatibility testing c
onducted on heart valve discs made by Medtronic showed results virtual
ly identical to those from testing of discs made by CMI.