Developments in cardiovascular valve technology - Biomaterials and Devices for the Circulatory System - page 86

and pericardial. This chapter discusses the major historical milestones in the
development of cardiac valves, in order to give the reader a perspective on
how innovative researchers in the early days of cardiac surgery, beginning
with Hufnagel and his original acrylic ball prosthesis, spurred the develop-
ment and clinical application of cardiac valve replacements. The historical
review culminates with the introduction of modern pyrolytic carbon-based
devices.
This chapter reviews clinical indications for valve replacement, with
emphasis on the aortic, mitral, and tricuspid valves, as well as the physiology
associated with valve replacements. Another section describes valve bioma-
terial and the effects of these materials on thrombogenicity, resistance or
susceptibility to infection. Finally, an introduction to newer biomaterial and
valve designs will further pique the reader, with the intent of spawning new
approaches in the ongoing refi nement of cardiac valves.

4.2 Historical perspectives

On September 11, 1952, Hufnagel performed the fi rst clinical implantation
of a mechanical valve prosthesis 16 following six years of experimentation in
his laboratory at Georgetown University Medical Center. Hufnagel's origi-
nal design was based on a bottle stopper, which had been patented by John
Williams in 1858. The device (Fig. 4.1) was implanted into the descending
thoracic aorta.
Although approximately 150 clinical cases utilizing the original Hufnagel
valve have been reported, the actual number of implants is unknown. A
case report in 1982 described the oldest known living recipient, a man who
survived with the implanted valve for 27 years before it was explanted due
to aortic dilatation. 17 Hufangel's success inspired Gordon Murray in 1955
to utilize a similar approach, but he substituted the prosthetic device with

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4.1 Hufnagel's caged-ball valve, designed for implantation in the
descending thoracic aorta in patients with aortic incompetence. Image
from the Historical Valve Museum collection, courtesy of Edwards
Lifesciences, Irvine, CA, USA.