Two Starr-Edwards artificial mitral valves, ball & cage design, USA, c 1979.
© Science Museum / Science & Society Picture Library
These heart valves are made of plastic and metal and contained in sterile cases made by Edwards Laboratories Inc. Mitral stenosis occurs when the three flaps of the mitral valve in the left side of the heart begin to fuse together and prevent the normal flow of blood. This was a frequent long-term consequence of rheumatic fever, once a common childhood illnes, but could be treated by replacing the heart valves. The first human implant of an artificial valve was performed in 1952.