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Editor: Marc Jay Bern
Profession: Defective Medical Device Lawyer

Category: About Sprint Fidelis Defibrillator Lead Lines

In an article on the LA Times website, Cardiologist Dr. William Maisel, a consultant to the FDA, explains what goes wrong with the Sprint Fidelis leads in defibrillators.

Several things can go wrong and cause the device to malfunction. In a 2006 study, Dr. Maisel and his colleagues discovered that over 2.6 million pacemakers and defibrillators implanted between 1990 and 2002, only 0.65% of them malfunctioned. A quarter of the problems were blamed on battery issues and a little more than a quarter were blamed on electrical issues.

The leads can go bad because the wire itself breaks (which is what happened in the Medtronic cases) or the insulation cracks. "What we wonder is how come they don't break more often," Maisel says. Not only do the wires have to handle 750 volts, but each time the heart beats, the lead moves. "That's 500 million movements over the life of the device," Maisel adds. "In a perfect device, that's 500 million consecutive signals without error. It's an amazing thing that we're asking these wires to do."

If a lead cracks or breaks, the device starts to receive electrical noise and thinks the heart is beating incorrectly. A pacemaker sends a tiny shock to the heart, but with defibrillators, patients can feel the power. Some patients describe the sensation as being struck by lightening or kicked in the chest by an elephant.

Often times, routine checkups can help give clues that the device is malfunctioning and not working properly. Doctors are able to measure the size of the electrical signal from the heart, how much energy it takes to pace the heart and the impedance of the wire. If the measurements are wrong, doctors commonly request an x-ray to help detect a crack in the wire.

Lead fractures can be hard to predict - the break is sudden in most instances.