Interference between GSM mobile phones and pace-makers: in vitro evaluation of interaction mechanisms

Aim of this study was to in-vitro evaluate the effectiveness of the filtered feedthrough assembly used to filter out the electromagnetic interference at the Input stage of Implantable pace-makers. We used three modified pace-makers of the same model, with an electrical connection to the output of the input sensing amplifier. The pace-makers differed for the level of protection against electromagnetic interference. We used a dual-band mobile phone. For each pace-maker the output of the sensing amplifier was monitored in 4 status: 1) no inhibition signal; 2) inhibition signal with amplitude 50% greater than the sensing threshold; 3) inhibition signal slightly lower than the sensing threshold; 4) inhibition signal slightly greater than the sensing threshold. For each pace-maker, evaluation has been performed in basal condition (no radiated power), during ringing and during talking. We found that the PMK with only the block capacitor shows asynchronous pacing and inhibition, while the other two PMKs do not interfere with the mobile phone, in any stage and for any mobile status.