services. We programmed both at maximal sensitivity (PD 140 maximal electromagnetic flux density 3.82 μT, MH 5 maximal electromagnetic flux density 6.3 μT).


Test Protocol Patients were examined in supine position under continuous 12-lead electrocardiogram (ECG) monitoring. Documentation of stored and programmed parameters was performed before and after exposure to the hand-held metal detectors to detect changes in parameter settings or inappropriate function. During continuous ECG recording, we swiped the activated hand-held PD 140 and MH 5 metal detector on the skin above the cardiac rhythm device and along the lead(s) for ≥30 seconds.


Results


388 patients (mean age 66±15yrs, 76% males) participated in the study. 209 patients had pacemaker systems, comprising 81 devices from 37 model families of 11 manufacturers corresponding to 73% of all pacemaker families available on the market within the last ten years. 179 patients had cardioverter-defibrillator devices, comprising 61 devices from 26 model families of 7 manufacturers corresponding to 76% of cardioverter- defibrillator families available on the market within the last ten years. We observed no abnormal pacemaker or cardioverter-defibrillator system function during or after exposure to hand-held metal detectors. For a detailed list of the device models please see the original article in the Annals of Internal Medicine6


. Discussion


In this assessment of interference between commonly used hand-held metal detectors and a variety of cardiac rhythm devices we were unable to identify any adverse effects of use on cardiac device function. We aimed to maximise the likelihood of interference by using the highest possible magnetic field of two commonly used hand-held metal detectors and by increasing the duration of exposure to 30 seconds per testing, which by


December 2011 Aviationsecurityinternational


far exceeds conventional screening durations. Aiming to increase the generalisability of our results, we used in our testing protocol two commercially available, widely applied, hand-held metal detectors with different strengths of magnetic field and technical characteristics similar to those of other hand-held metal detector systems used for screening procedures. Our results are consistent with


previous studies which showed no electromagnetic interference when device recipients walked through metal detector gates which cause an electromagnetic field of even higher strength compared to hand-held metal detectors4,7


. The risk of clinically significant


interference between hand-held metal detectors and implanted cardiac rhythms devices seems unlikely for several reasons. First, pacemaker function may be inhibited when inappropriate signal detection (oversensing) exceeds the programmed threshold of sensitivity. In pacemaker-dependent patients, inhibition of pacing may cause loss of consciousness when the duration of the resulting pause exceeds six seconds8


.


This time period is not reached during a routine screening procedure, where the


device is exposed for a maximum of three seconds to the electromagnetic field of the hand-held metal detector. Second, in patients with implanted cardioverter- defibrillators, inappropriate detection of ventricular fibrillation and delivery of


shocks would require repeated


oversensing to satisfy detection criteria that is very unlikely provoked by a short screening procedure. Third, in patients with cardioverter-defibrillators, inappropriate detection of ventricular tachycardia and therapy delivery would require a stable oscillating signal with a frequency between 100 and 230 beat per minute. This is unlikely to be induced by an electromagnetic field of a hand-held metal detector. Nevertheless, our negative findings cannot be considered definitive


although a large variety of device models was examined in our study. Results are restricted to the device models


www.asi-mag.com


CI D 140 hand- held magnetometer


EA P 31


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52