Following the most recent recall of its controversial heart valve--the fourth in the breakage-prone valve's six-year history--the president of Shiley Inc. says the company is pinning its hopes for the future on an upgraded model.
Robert Curtis, Shiley's president and chief executive officer, said Wednesday that the Irvine-based company has developed another valve, almost identical to the one being recalled--that has been engineered to resist the breakage that so far has been linked to the deaths of about 18 heart valve recipients in the past three years. Shiley, Curtis said, plans to submit an application to the U.S. Food and Drug Administration for approval to market the new valve in the United States. It has been used in Europe since 1982.
He said the company, a subsidiary of the giant Pfizer pharmaceutical conglomerate, hopes to begin selling the valve in the United States early next year.
"That's the valve of the future for us," Curtis said of the valve that the company has named the "Monostrut."
Shiley's public announcement of the Monostrut valve comes after the company reported Friday that it was recalling all of the 60-degree larger size Bjork-Shiley convexo-concave valves manufactured since February, 1982, that have not been implanted.
Curtis said Wednesday that about 12,000 of the valves in 29-, 31- and 33-millimeter sizes were produced since February, 1982. All but 1,100 of those have been implanted in patients whose natural valves have failed.
The valves consist of a cobalt ring and a pyrolytic carbon disk that is held in place by two cobalt struts. When operating properly, the struts allow the disc to open and close, enabling blood to pass through the heart.
Heart surgeons and cardiologists say that the Bjork-Shiley 60-degree valves show less incidence of blood clotting and allow easier blood passage than do many other mechanical valves developed since the 1960s.
The chronic problem with the larger valves, which has prompted their repeated recall over the years, involves the fracture of a cobalt strut that allows the valve to swing open. When that strut gives way, the disk is lost in the patient's body and the heart can no longer pump blood.
According to the Food and Drug Administration, fractures have occurred in 28 of the larger valves manufactured since February, 1982, the date of the last recall. Of those failures, about two-thirds resulted in deaths.
Shiley initially offered to recall only valves manufactured from February through June, 1982, because an unusually high number of those valves had failed. But FDA officials said they believed it was too early to tell whether the valves manufactured after that time were any safer. At the FDA's request, Shiley agreed to take all of the valves off the market.
Curtis said Wednesday that Shiley has no plans to continue production of the larger size 60-degree convexo-concave valve model. He said that "the popularity of the valves has decreased in the last year," as surgeons have switched to other models.
One of the models physicians overseas are turning to, Curtis said, is Shiley's Monostrut. Since 1982, he said, Shiley has had FDA approval to sell that valve in Europe, where the company has been collecting data on its performance.
Curtis said that the Monostrut valve operates exactly like the 60-degree convexo-concave valve and has the same medical benefits. It is also sells for about the same price, $2,000.
The major difference, he said, is that the outlet strut on the recalled model was welded to the valve ring in two places and sometimes would break at the points of attachment. The outlet strut on the Monostrut is carved out of the same piece of metal as the ring and is therefore much stronger.
Curtis said that more than 12,000 Monostrut valves have been implanted in Europe since 1982 and that so far there have been no strut fractures.