When I was just beginning my career in biomaterials and medical devices, I heard about a truly dramatic breakthrough in heart valve design. Dr. Bjork and the Shiley Corporation had invented a radically different, hinge less, mechanical valve that held the promise of long-term functionality. The free-floating carbon occluder opened and closed against two metal ‘stents’ that kept the occluder from escaping. It was immediately recognized as the best performing valve on the market, by far. Sales soared, the company prospered, and patients absolutely benefitted from this remarkable innovation. Here is a picture of the original Bjork-Shiley Concavo-Convex valve:
But when the company tried to further improve the valve’s performance by allowing the occluder to open further (to 70 degrees instead of 60 degrees) the outflow strut started to develop cracks and occasionally failed at the weld, first on one side, and the all together, allowing the occluder to escape and almost always causing the patient to die before help arrived. The company, with the FDA’s approval, continued to sell their valve while they tried to fix the problem. During the years that this “learn while you earn” policy was in place, more that 82,000 valves were implanted, and at least 400 patients died from catastrophic valve failure. The product was eventually recalled, there were massive class-action lawsuits that went on for decades, and the whole incident is still referred to as one of the worst medical device recalls in history. This is a very short version of a very long story.
Over the years, I have tried to figure out what are the optimum lessons to teach from this disaster. Slowly over many years, the real reasons for these failures were finally determined. I (and many others) have written whole lecture series just on the forensic metallurgy of the fatigue failure that occurred and caused the failures at the weld sites. Another stunning fact is that the FDA did not have a single statistician on staff at the time (1979-1982), and a detailed analysis of the actual risks and benefits of recalling and replacing these valves was not attempted until much later in the history of the case. This was the basis of lectures on “How Safe is Safe Enough?” The lawyers were quickest to point out that the company made many serious errors of judgment during every stage of the long ordeal. Some were honest, but misplaced, attempts to keep the best available product on the market, some were just stupid, and some were later determined to be acts of deliberate, criminal negligence. I have discussed this failed decision “chain-of-command” at the company with my management students to explore how crisis scenarios like this one can be better anticipated, prepared for, and responded to with more effectiveness and with much more efficiency. This is just the beginning of the list of case-based topics that have been discussed and analyzed for over three decades, and the debate even continues today. Imagine the terabytes of doctoral dissertations that will be generated by the BP disaster!
But I was recently trying to make a different kind of point with a large group (over a hundred) of senior biomedical engineering students and found that this old case still had a few more pedagogical tricks up its sleeve. What are the ethical dilemmas created when we push our engineers to be “innovative”? What is their responsibility to their “customers” when their inventions go awry? What does it really mean when we say in our strategic plan that we are educating “societal engineers”? Those are really the questions I want to explore in the first story I want to share with you, and that is where I will start in my next post!
Note to readers: Thanks for your early comments, suggestions, and critiques. They are all very helpful so keep them coming! I added the subscription widget today (thanks, Jeff!) so now you can more easily follow this blog as it evolves.
For those who were expecting a complete curriculum on day one, I am afraid you will have to be a little patient. This is going to take a while. As Antoni Gaudi once said about his famous cathedral, “Don’t worry, my client is in no hurry!”