Artificial heart valves are used to replace damaged or diseased heart valves that can't be repaired. Hundreds of people have had to have their Bjork Shiley heart valves replaced because of strut fractures and other safety issues. Worldwide, 619 valve fractures have been reported to Shiley. Defective Bjork Shiley heart valves were implanted in more than 40,000 Americans and approximately 86,000 persons worldwide. In approximately two thirds of the cases, it is reported the patient died following the valve fracture.

Shiley manufactured and sold the Bjork Shiley Convexo-Concave (BSCC) valve between 1979 and 1986, until the Food and Drug Administration (FDA) forced it off the market. Pfizer purchased Shiley in 1979 at the onset of its BSCC valve ordeal. In 1992, after years of litigation, Pfizer sold Shiley's businesses to Italy 's Sorin Biomedical. Sorin opted not to purchase rights to the BSCC valve. Later a firm by the name of Alliance Medical Technologies, composed of former Shiley and Pfizer employees, purchased the rights to Shiley's Monostrut heart valve line from Sorin.