Monoleaflet Tilting Disc Valves

Abstract

Three companies (Medical Incorporated, Shiley Laboratories, and Kastec, Inc.) began providing five different versions of tilting disc valves. Two emanated from the University of Minnesota, conceived by Walt Lillehei and Robert Kaster and covered by patents owned by the University. Another was conceived by Don Shiley, previously employed by Edwards Laboratories, who patented an alternative design called the Bjork-Shiley valve with a carbon occluder and metallic struts. There was legal action by the University of Minnesota, but the court ultimately ruled the Shiley design did not infringe the University’s patents; however, continuing reports of metallic strut failures clouded the future for the Shiley valve. Over the same time frame, Medical Incorporated converted its Lillehei-Kaster valve to the Omniscience valve with a metallic orifice and a carbon occluder and then on to the development of an all carbon version called the Omnicarbon valve. In 1975, Bob Kaster split from Medical Incorporated to form Kastec, Inc. to pursue a unique design that was ultimately acquired in 1979 by Medtronic, Inc. and marketed as the Medtronic-Hall valve with General Atomic as supplier of Pyrolite discs. By 2003, Medical Incorporated sales of its Omnicarbon valve, facing Medical Carbon Research Institute’s newly introduced On-X valve technology that had received the CE mark in Europe and FDA approval in the United States, decided to cease doing business. At about the same time, a Special Report titled Twenty-Five Year Experience with the Bjork Shiley Convexo-Concave Heart Valve: A Continuing Clinical Concern, May 31, 2005 (Circulation, May 31, 2005) caused Shiley’s demise.