May 20, 2003 (Washington, D.C.) -- Hundreds of thousands of Americans who have tiny lifesaving devices implanted under their skin worry every time they approach a metal detector -- will the security device turn off a pacemaker or cause an implanted defibrillator to send an unnecessary shock? Most patients heed advice from manufacturers and simply avoid metal detectors, but that means submitting to an old-fashioned "frisk" before boarding a plane.
Now, new research from a team of German heart specialists suggests that metal detectors actually pose no risk to patients with implantable defibrillators, also called ICDs, or pacemakers. Since metal detectors have moved beyond airport security and into schools, this is clearly a welcome finding, says Stephen C. Hammill, MD, professor of medicine at the Mayo Clinic Medical School in Rochester, Minn.
The new findings were presented at the annual meeting of the North American Society for Pacing and Electrophysiology.
Since these tiny devices are carefully calibrated to either keep the heart beating at a healthy rate (pacemaker) or to deliver a lifesaving jolt of electricity that shocks an erratically beating heart back into regular rhythm (implanted defibrillator), there was concern that any interference from a magnetic field would disrupt these devices. "There is always a concern that when a magnet comes near the device it may cause it to malfunction, or wipe out its memory," Hammill says.
In the new study, researchers from the German Heart Institute in Munich tested a standard airport metal detector on 148 implanted defibrillator patients who agreed to be tested during a routine office visit. First, the patients walked through the detector twice, and then "they stood inside the detector and turned around slowly," Sonja Weyerbrock, MD, tells WebMD. "In no case did the metal detector cause any problems, and we feel that we can safely say that device patients should not worry about metal detectors," she says.
She says that the metal detector used in the study is made in Italy and is used at all European airports and about half of the airports in the U.S. But there is "virtually no difference in the magnetic fields among metal detector manufacturers, so we think these findings apply to all metal detectors."
Moreover, all four major implanted defibrillator makers -- Guidant, Medtronic, St. Jude Medical/Ventritex, and Biotronik -- were represented. "I think this is as complete a picture as we can get," Weyerbrock says.
Weyerbrock says next month her group will publish a study in the Journal of the American College of Cardiology that concludes that metal detectors have no adverse effect on either implanted defibrillators or pacemakers. "We conducted the pacemaker study the same way as we tested the ICDs, and both devices will be discussed in our upcoming study."
Hammill says the new report joins a series of studies that have debunked some earlier concerns. "At first we had some concerns about cell phones, but after that issue was studied, it was determined that cell phones posed no risk as long they were not carried in an inside pocket over the device," he tells WebMD.
The next concern was "theft detectors in stores. There was a report that a patient stood inside the detector for several minutes and as result the patient's pacemaker turned off and the patient collapsed. But additional study demonstrated that there is no danger from theft detectors as long as patients don't unnecessarily linger inside them," he says.
The American Heart Association estimates that about 145,000 pacemakers were implanted in 2000, the last year for which data are available, and the North American Society for Pacing and Electrophysiology estimates that about 100,000 Americans receive implanted defibrillators every year.
Finally, Hammill says, "This is really good news for these patients because it means they have one less worry." But he says that it will probably take some time before the standard warnings about metal detectors are dropped by device manufacturers.