The Bjork-Shiley valve is a mechanical
heart valve prosthesis. Beginning in 1971, it has been used to replace the aortic or mitral valves. It marks the first example of a successfully used tilting-disc valve. It was manufactured first by Shiley Inc., then later by Pfizerafter that company purchased Shiley. One model of the Bjork-Shiley valve became the subject of a famous lawsuit and recall after it was shown to malfunction, usually fatally, in a number of cases.
The Bjork valve consists of a single carbon-coated disc in a
metalhousing. The discs are held in place by two metal struts, an inflow and an outflow strut. The standard design Bjork-Shiley valve is a very durable valve and was widely used in the 1970s. [cite web |url=http://www.rjmatthewsmd.com/Definitions/valves.htm |title=Valves |accessdate=2006-05-28]
Attempts to improve the design of the valve and speed manufacturing, however, led to a weaker structure, with serious consequences. Beginning in 1979, Bjork-Shiley valves with the convexo-concave design had a tendency to develop fractures in the outflow strut which could result in catastrophic valve failure and possibly sudden cardiac death. Later analysis revealed that the strut was fracturing at the place where it was welded onto the metal valve ring. One end of the strut would fracture first, followed by the second strut some months later. Eventually, 619 of the 80,000 convexo-concave valves implanted fractured in this way, with the patient dying in two thirds of those cases. The convexo-concave valve was forced off the market by the FDA in 1986. [cite web |url=http://www.yourlawyer.com/topics/overview/bjork_shiley_heart_valve |title=Bjork-Shiley Heart Valve |accessdate=2005-05-28] Valves welded by specific welders were at greater risk of fracture. The Convexo-Concave valve was withdrawn from the market and multiple
lawsuitsfiled. This recall and legal struggle have been described as "perhaps the most infamous recall case on record". [cite web |url=http://www.lawyersandsettlements.com/articles/bjork.html |title=Lethal Defects of Bjork-Shiley Heart Valve| last=Pringle| first=Evelyn |accessdate=2006-05-28]
Not all of these valves were removed and replaced. The risk of valve fracture must be balanced against the risk of the surgery to replace the valve.
Decision tools have been published and are available from a trust set up for this purpose during the litigation surrounding the valve "recall". The tools take into account patient age, the size and location of the valve ( aorticor mitral) and other factors to come up with a recommendation as to whether surgery to replace the valve is worthwhile. In some patients the risk of surgery to replace the valve is higher than the risk of the valve fracturing. A compensation fund was also established to provide money for patient compensation and to pay for the costs of heart surgery to replace the valve.
More recent models of the Bjork-Shiley valve did away with the convexo-concave design and are reliable valves that do not require replacement.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Björk (disambiguation) — The name Björk or Bjork can refer to:* Any woman in Iceland with Björk as her given name. It s a fairly common Icelandic name given to girls meaning birch, specifically the only native tree of Iceland, Betula pubescens tortuosa (Arctic Downy… … Wikipedia
valve — 1. A fold of the lining membrane of a canal or other hollow organ serving to retard or prevent a reflux of fluid. 2. Any formation or reduplication of tissue, or flaplike structure … Medical dictionary
Björk — V. O., 20th century Swedish cardiothoracic surgeon. See B. Shiley valve … Medical dictionary
Shiley — D. B., 20th century U.S. engineer. See Björk S. valve … Medical dictionary
Artificial heart valve — An artificial heart valve is a device implanted in the heart of a patient with heart valvular disease. When one of the four heart valves malfunctions, the medical choice may be to replace the natural valve with an artificial valve. This requires… … Wikipedia
Donald Shiley — Donald P. Shiley Born Donald Pearce Shiley January 19, 1920 Died July 31, 2010 (aged 90) Donald Pearce Shiley (January 19, 1920 – July 31, 2010) was one of the co inventors of Pfizer s Bjork–Shiley heart valve. He was a 1951 alumnus of the… … Wikipedia
Viking Bjork — (born 1919) is a Swedish cardiac surgeon.In 1968 he collaborated with American engineer Donald Shiley to develop the first monostrut tilting disc valve used to replace the aortic or mitral valve. The Bjork Shiley heart valve was manufactured by… … Wikipedia
B-S — Bjork Shiley [valve] … Medical dictionary
B-S — • Bjork Shiley [valve] … Dictionary of medical acronyms & abbreviations
Marian Ionescu — Marian Ion Ionescu Marian Ion Ionescu (born 21 August 1929) is a pioneer British cardiac surgeon who spent his professional life initially in his native Romania and afterwards, the main part of his productive life in Great Britain. His interest… … Wikipedia