The Björk-Shiley Convexo-Concave valve — a Welded Strut That Snapped and Killed Two-Thirds

When Shiley Inc. and its parent Pfizer pulled the Björk-Shiley Convexo-Concave (BSCC) heart valve from the world market in 1986, the device had been sold for seven years as a refinement of an already trusted prosthesis — and the refinement was the thing that killed people. Co-invented by American engineer Donald Shiley and the Swedish cardiac surgeon Viking Björk, the convexo-concave disc was a geometric tweak meant to improve blood flow over the company’s well-regarded flat-disc tilting valve. To make the new geometry work, the outlet strut that captured the swinging disc was changed and welded to the valve ring. That weld was the flaw. Under the relentless cyclic load of roughly 40 million heartbeats a year, the strut fractured at the weld, the disc escaped, and the valve failed catastrophically — often producing sudden death before the patient could reach an operating room.

The harm was not a rare anomaly tolerated by an unlucky few. Of the roughly 86,000 convexo-concave valves implanted worldwide, more than 600 are documented to have fractured, and in approximately two-thirds of those cases the patient died. The 60-degree version received U.S. Food and Drug Administration approval in 1979; a higher-flow 70-degree variant was sold abroad but never cleared in the United States, and it fractured at even higher rates. Because the failure mode was a fatigue crack that gave no reliable warning, surgeons and patients spent the late 1980s and 1990s trapped in an excruciating calculus: a working valve might snap tomorrow, but elective re-operation to remove it carried its own mortality.

What turned a metallurgical defect into a scandal was the factory. Sworn testimony and a 1984 engineer’s complaint described a Shiley plant in Irvine, California where valves rejected by inspectors were fished back out, reground to hide cracked welds, renumbered, and passed with falsified paperwork — welders were poorly trained, equipment was in “horrible” condition, and struts were forced onto flanges with pliers. The legend of an improved valve concealed a manufacturing line that could not reliably make the one weld on which a patient’s life depended. Litigation, not the FDA, ultimately fixed the price: the Bowling v. Pfizer class action settled in 1992 for roughly $215 million, with a further fund earmarked for future fracture claims, while implanted patients carried the device — and the fear — for the rest of their lives.