(You are encouraged to copy and distribute this information)
September 28, 1998
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To: |
Cardiologists Cardiovascular Surgeons Emergency Physicians Neurologists Neuro Surgeons |
I am writing to let you know that the operation of certain medical devices, including pacemakers, implantable cardioverter/defibrillators and spinal cord stimulators, may be affected by the electromagnetic fields produced by anti-theft systems and metal detectors. The number of reported significant patient injuries is very low, and we are working with both the manufacturers of medical devices and the manufacturers of anti-theft systems and metal detectors to resolve this issue. In the meantime, you may use the following information and recommendations to help your patients prevent or minimize any adverse effects.
Anti-theft systems, also called electronic article surveillance (EAS) systems, are used in a wide variety of settings, including supermarkets, shopping malls and libraries. They typically consist of one or two columns placed opposite each other near entrances and exits. Several technologies are currently on the market, but generally an electromagnetic detection field is produced between the two columns and an alarm sounds if an article with a special tag is carried between the columns.
Metal detectors for airport and facility security applications can be either portals that a person walks through, or can be hand-held "wands" that are passed over a person’s body. Metal detectors use various technologies involving magnetic fields to detect the presence of metal.
In the past 10 years, FDA has received 44 adverse event reports where EAS systems and metal detectors appeared to interfere with the routine function of implantable pacemakers, implantable cardioverter/defibrillators and spinal cord stimulators. Similar events have also been reported in the literature. We believe that EAS systems or metal detectors can potentially interact with other electronic medical devices as well.
We have received 18 reports of interference of pacemakers from both EAS systems and metal detectors. The types of responses to the interference reported were: shifts in pacing rate; alteration to programmed pacing therapy; presyncope and syncope; and chest pain.
Effects reported in the literature from clinical laboratory investigations include: reversion to noise mode (asynchronous pacing at a predetermined rate); oversensing resulting in inhibition of pacing output in either chamber; and atrial sensing of the EAS field resulting in "tracked" ventricular pacing at pre-set limits. These reactions were typically transient.
We have received 2 reports of ICDs inappropriately shocking patients; one patient was leaning against an EAS system, and the other was being scanned with a hand-held metal detector. In 7 other reports, ICDs reverted to "monitor only" mode after being exposed to metal detectors.
We have received 17 reports of overstimulation from implanted spinal-cord stimulators when persons with these devices passed through security systems. (It was not reported whether the security systems were EAS systems or metal detectors.) Patients reported pain, jolts and shocks; in one case, a patient fell and was injured.
Interactions with EAS systems and metal detectors are unlikely to cause clinically significant symptoms in most patients. However, to be on the safe side, you may wish to advise patients with electronic medical devices, particularly those who are dependent on the device (e.g., pacemaker dependent), to take some simple precautions:
FDA solicits your help in collecting data on adverse events related to electromagnetic interference from EAS and metal detector systems as well as any other source. Practitioners who are employed by health care facilities that are subject to FDA’s user facility reporting requirements should follow the reporting procedures established by their facility. Practitioners can also report the incident directly to MedWatch, the FDA’s voluntary reporting program. The reports can be submitted by phone at 800-FDA-1088, by fax at 800-FDA-0178, or by mail to: MedWatch, Food and Drug Administration, HF-2, 5600 Fishers Lane, Rockville, MD 20857.
If you have any questions regarding this letter, please contact Nancy Pressly, CDRH, Office of Surveillance and Biometrics, HFZ-510, 1350 Piccard Drive, Rockville, MD 20850, FAX 301-594-2968, or e-mail nap@cdrh.fda.gov. Additional copies of this notification can be found on the FDA webpage at http://www.fda.gov/cdrh/safety.html. Postmarket safety notifications can also be obtained through e-mail on the day they are released by subscribing to our list server. To subscribe, visit http://service.govdelivery.com/service/subscribe.html?code=USFDACDRH_10 Additional information on medical devices and electromagnetic compatibility can be found on the FDA webpage at http://www.fda.gov/cdrh/emc/index.html.
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Sincerely yours, D. Bruce Burlington, M.D. |
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