Turns out that Medical Device companies have making tweaks to their devices without putting them through human testing.  Calamity ensues.  First, Do No Harm.

A few years ago, the Food and Drug Administration announced a stunning recall, saying that electrical wires in some St. Jude Medical heart defibrillators, which were implanted in tens of thousands of people, were defective. It was a rerun for cardiac patients: In 2007, Medtronic recalled its Sprint Fidelis cardiac devices because of faulty wires.

In both cases, the F.D.A. warned that the wires could cause painful shocks or fail when needed, and patients were left to choose between living with the leads under close monitoring or having dangerous surgery to replace them. Both companies reported deaths linked to the flawed leads.

Now a new paper by Harvard researchers, using records only recently made available by the F.D.A., explains how the faulty leads got onto the market, shedding light on a little-known process used by manufacturers to alter medical devices without putting them through human trials. (An approval pathway for lower-risk medical devices, called the 510(k) clearance, has received more public scrutiny, including harsh criticism from the Institute of Medicine.)