The initial development process in the field of prosthetic heart valves involved the search for biologically compatible materials and hemologically tolerant designs; success could not be achieved without the union of these two factors. At that time, there was no satisfactory mechanism to achieve this goal scientifically; a trial-and-error method was used. The development of prosthetic heart valves became the purview of numerous cardiovascular surgeons, who often collaborated with engineers; to distinguish one valve from another, each prosthesis often became identified with the surgeon developer (6).
Lillehei and his colleagues developed four different valves: (1) a nontilting disk valve called the Lillehei-Nakib Toroidal Valve in 1967; (2) two tilting disk valves, the Lillehei-Cruz-Kaster in 1963 and the Lillehei-Kaster in 1970 (produced by Medical Inc. in 1970 and eventually distributed by Medtronic Inc. in 1974); and (3) a bileaflet valve, the Lillehei-Kalke in 1965 (manufactured by Surgitool [now Medical Engineering Corporation, Racine, WI] in 1968 and used clinically by Dr. Lillehei at the New York Cornell Medical Center) (Fig. 12).
The st. Jude bileaflet valve was designed by chris Posis, an industrial engineer who approached Demetre Nicoloff MD, a cardiovascular surgeon at the university of Minnesota. This valve had floating hinges located near the central axis of the rigid housing as well as an opening to the outer edge of each leaflet, leaving a small central opening (Fig. 13) (7). Nicoloff first implanted this valve in october 1977, and it provided the foundation for the beginning of St. Jude Medical Inc. Dr. Nicoloff was asked to serve as the medical director of the new company; however, he declined because of the demands of his clinical practice. Rather, he suggested that Dr. C.W. Lillehei become the medical director, a post that Lillehei held until his death in 1999 (6).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.