Methods and results of
in vitro experiments examining the electromagnetic interference (EMI) imposed on active implantable medical devices (AIMDs) by electronic article surveillance (EAS) systems are presented. Examined EAS systems include eleven models provided by four manufacturers. They are classified into four categories according to operating principle, and consist of one magnetic-type system, four acousto-magnetic type systems, five electromagnetic-type systems, and one microwave-type system. Examined AIMDs include five models of implantable cardiac pacemakers and five models of implantable cardioverter defibrillators (ICDs) provided by six manufacturers. These EAS systems and AIMDs are currently available in the Japanese market. The
in vitro test system is based upon Irnich's flat torso phantom. The observed EMI on pacemakers is either missing pulses or undesirable generation of asynchronous pulses. The observed EMI on ICDs are inappropriate tachyarrhythmia detection and erroneous delivery of therapy. To summarize the results, in the worst case for pacemakers, interference occurred when approaching the EAS system up to 90 cm and entering the gate of the EAS system. The most significant effect was complete omission of pacing pulse and continuous generation of asynchronous pulses. These were observed when the pacemaker was set at maximum sensitivity. In the worst case for ICDs, interference occurred when approaching the EAS pedestal up to 90 cm within the gate. The most significant effect was inappropriate or inhibited tachyarrhythmia detection at 60 cm. These effects were drastically suppressed when the sensitivity was reduced and when the AIMD was far from the EAS system and magnetic field was attenuated. All AIMDs that experienced EMI returned to normal operation mode upon departing the EAS system.
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