Tests of pacemakers and implantable cardioverter-defibrillators indicate that patients with such devices are unlikely to experience any problems while passing through standard airport metal detector gates, according to an article in the June 4th issue of the Journal of the American College of Cardiology.

"Testing a lot of different pacing devices, we have not seen any interference. Currently, patients are not obliged to walk through the metal detector gate, but if they did, it would not harm their health or their device," said Christof Kolb, MD, lead author of the German study. "Whether the results of this study mean that pacemaker or implantable cardioverter-defibrillator patients should generally be allowed to cross airport metal detector gates has to be determined by government authorities," he added.

The researchers set up a standard airport metal detector in their clinic and then studied 348 patients who came in for routine checks of their pacemakers or implantable cardioverter-defibrillators. The 200 pacemaker patients were connected to an electrocardiogram while passing through the equipment. The investigators turned off the electric shock capability, but not the heart rhythm sensors, of the cardioverter-defibrillators in 148 patients during testing. After the test, the researchers downloaded the internal monitoring data from the cardioverter-defibrillators to see whether they detected any external electromagnetic signals that might have triggered an inappropriate shock.

Patients with such heart device implants are often warned to avoid airport metal detectors. Other devices, such as electronic theft detectors in stores, have been known to cause electromagnetic interference. For pacemaker patients, such interference could block pacemaker signals and interrupt heart rhythm. Interference could cause cardioverter-defibrillators to falsely detect a dysrhythmia and trigger a painful shock unnecessarily.

Despite the growing use of both implanted heart devices and electromagnetic security sensors, Kolb said the last study of airport metal detectors was done 15 years ago, using older varieties of pacemakers. He added that implantable cardioverter-defibrillators have not been systematically studied in airport metal detectors.

"I was often asked by pacemaker or cardioverter-defibrillator patients questions like this: What would happen if I passed an airport metal detector by accident? What would happen if I was urged to cross an airport metal detector gate? For example, in a foreign country when I don't speak the language or airport officials don't accept the pacemaker or implantable device card? Especially after September 11th patient questions concerning this topic increased a lot. I was not able to give a definite answer. This prompted me to test whether or not there is a hazard for these patients," Kolb said.

The researchers studied a large number of patients who had a variety of U.S. and European pacemakers and implantable cardioverter-defibrillator devices in order to look for rare cases of interference. Kolb said laboratory bench tests of the devices would not have guaranteed that the results could be applied to real-life situations.

Charles D. Swerdlow, MD, who was not part of the research team, said, "This study has a lot of practical value. Cardiologists can recommend to their patients with pacemakers and defibrillators that they can walk through airport metal detectors without any special notification of the security or staff or special screening."

Steven L. Higgins, MD, who also was not connected with the research team, noted, "Patients underwent a 'worst-case scenario'" test including prolonged evaluation within the metal detector in various positions. Since most passengers spend only a few seconds within the airport metal detector, this study provides reassurance that these detectors are likely safe."