Valve failure

Press, 25 July 1984, Page 21

Valve failure

A woman has died in Britain after the failure of an artificial heart valve implanted 14 months ago. The valve, one of a type fitted to several hundred heart patients in Britain, malfunctioned because of metal fatigue, an inquest in South Yorkshire has been told. The manufacturers, Shiley. Incorporated, of Irvine, California, said last week that at least four other patients wearing the same kind of valve had died in Britain. The last victim, Mrs Beryl Inston, a wages clerk from Bilston, near Wolverhampton, died while visiting her son in Doncaster. The heart valve failed when one of the struts holding it in place gave way. An emergency operation at Sheffield’s Northern General Hospital successfully replaced the valve, but too long had elapsed since Mrs Inston’s collapse for her to regain consciousness. It is understood that the valve was one of a faulty batch which came on to the market in 1981 and which has been associated with about 60 deaths world-wide. The remainder were subsequently withdrawn. Although doctors are aware of the valves’ weaknesses, the risks associated with removing and replacing them are considered greater than the risks of leaving the valves in place. The faulty valves were a version of the Bjork-Shiley 60 degree Con-vex-Concave valve, which was developed by Professor Viking Bjork of the Karolinska Institute, Sweden, and Don Shiley, chairman of Shiley Inc. Resembling a saucer-shaped disc set in a circle, they were introduced in the 1970 s and considered a considerable improvement on previous designs. Over-all failure rate of the 60

degree valve is given by the company and by the Food and Drug Administration (the U.S. Government’s medical watchdog) as sbghtly more than one in 1000 valves. But this includes the withdrawn batch, and a more realistic failure rate, said the company spokesman, is six in 10,000. The general structure of the Shiley valve is said to offer the advantage of an easier blood flow and much less clotting, which is a major cause of death with a number of other valves. “The over-all complications with our valves are much less than with any of the competitors. And we know this through independent studies over which we have no control,” said the spokesman. However, there is growing discussion in the medical press about the Shiley valve, and the F.D.A. is urgently reviewing the claim that its advantages outweigh its disadvantages. A meeting with the manufacturers is soon to be held. An F.D.A. spokesman for the cardio-vascular division said the valve is under review by the F.D.A. as to whether it should remain on the market. Valves may be replaced following failure if caught rapidly. A Shiley spokesman noted: ’‘failures from metal fatigue usually occur during the first 18 to 24 months after implantation. If people get past this time they appear to be all right and our statistics are beginning to show this.” Artificial valves are used to replace a patient’s own when they have suffered irreparable damage, often from the effects of rheumatic fever. They allow the blood to be pumped through the chambers of the heart and out into the bloodstream, but close to prevent it returning. (Copyright — London Observer Service.)