Attempts at replacing diseased natural human valves with prostheses began about four decades ago. The details of the development of heart valve prostheses, design considerations,

in vitro

functional testing, and durability testing of valve prototypes can be found in several monographs [Shim and Lenker, 1988; Chandran, 1992]. The heart valve prostheses can be broadly classified into

mechanical prostheses

(made of non-biological material) and


(made of biological tissue). Currently available mechanical and tissue heart valve prostheses in the U.S. are listed in Table 7.1.