The recent failure of hundreds of Bjork-Shiley Convexo-Concave (C/C) mechanical heart valves provides a case study on how information about the risk of failure was communicated to patients and the medical community.

In 1979 Shiley introduced a similar valve, the 60[degrees] Convexo-Concave (C/C), which they believed would improve blood flow through the valve.

Early in 1980, we asked that a selected group of Convexo-Concave valves be returned to Shiley for evaluation [the first recall] due to an incidence of strut fracture of .000103 (1.03 x [10.sup.-4]) per implant-month.

Although the C/C valve has a much higher rate of fracture, that is more than offset by "a 47% reduction in serious complications with the Convexo-Concave valve."[19]