Viking Olov Björk was a Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 cardiac surgeon.

In 1968, he collaborated with American engineer Donald Shiley

Donald Shiley

Donald Pearce Shiley was one of the co-inventors of Pfizer's Bjork–Shiley heart valve. He was a 1951 alumnus of the University of Portland, where he studied engineering....

 to develop the first "monostrut tilting disc valve" used to replace the aortic

Aortic valve

The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....

 or mitral valve

Mitral valve

The mitral valve is a dual-flap valve in the heart that lies between the left atrium and the left ventricle...

.

The Bjork–Shiley heart valve

Heart valve

A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...

 was manufactured by Pfizer

Pfizer

Pfizer, Inc. is an American multinational pharmaceutical corporation. The company is based in New York City, New York with its research headquarters in Groton, Connecticut, United States...

after they bought the Shiley company in 1979. In 1980 Björk wrote to Pfizer threatening to publish cases of valve failures — often fatal to the patients — unless corrective action was taken. This eventually led to long lawsuit that involved the recall of all existing valves and Pfizer allocating up to US$20 million to pay compensation.

Björk died on 18 February 2009.