Electronic anti-theft systems pose a threat to cardiac device patients

shape as they would be in a patient and the devices were tested in unipolar and bipolar settings. The distance between devices and the floor was set for average height patient. Devices were tested in static positions and using a robot to simulate a patient walking through the EAS systems, leaning towards them, and facing them.

The investigators found that the pedestal systems interfered with cardiac device functioning particularly when the devices were in close proximity and lingered. Devices programmed for unipolar sensing had the most interactions which included prolonged inhibition of pacing and inappropriate ICD therapy. Devices programmed with bipolar sensing showed fewer interactions but unintentional shocks and other inappropriate tachycardia therapy was observed.

Professor Stevenson said: “Significant interactions occurred with nearly all the pacemakers and ICDs when the robot closely faced the EAS system and the device lead loop was parallel to the EAS system loop. Facing or having your back to an EAS pedestal or a toddler with a pacemaker crawling over a subfloor system is of particular concern.”

Wall (doorframe) systems did not interfere. Preliminary tests of under floor systems (only two CIED manufacturers), which are completely hidden, did not interfere when flat or at a 30 degree angle from vertical. Professor Stevenson said: “We know from the physics that at 90 degrees (this is when the patient’s chest is close and parallel to the floor) we would likely have serious interactions. Further testing is needed to find out when the angle becomes dangerous. I suspect it will be about 45 degrees. This angle could occur with a patient really slouching in a chair for example.”

He continued: “Unipolar sensing is sometimes required but otherwise I would urge doctors to use bipolar sensing since the lead loop area is smaller, lowering the chance of interference. Doctors must educate patients about the potential dangers of EAS systems as many have never been warned not to lean or linger in retail store entrances. It is particularly important that patients do not sit or slouch in a chair or couch in store entry areas.”

Professor Stevenson concluded: “Electronic anti-theft systems are a part of everyday life, with more than 800 000 pedestals alone installed worldwide. Patients are safe if they walk at a constant pace through the system. EAS gates that are obscured with advertising or goods for sale, or hidden in the floor with couches or chairs adjacent, are a serious concern and EAS manufacturers have a responsibility to ensure that retailers install them in such a way that they are visible and well marked.”