It was reported that low impedance was observed on vns patient's system implanted on (b)(6) 2015.The impedance was already found to be low some times before, but when the patient's device was checked in (b)(6) 2016, 3 system diagnostic tests were performed which showed impedance values of 600 ohms, 3000 ohms and again less than 600 ohms.X-ray was taken and sent to the manufacturer for review.The generator appears on the x-ray to be placed in upper chest in normal arrangement.The filter feed-through wires appears to be intact.The pin connector appears to be fully inserted.The electrodes appeared to be placed in normal arrangement.It is unable to assess the presence of the strain-relief bend and loop and if they were placed as specified by labeling.One tie-down is visible to secure the implanted lead.A portion of lead behind the generator could not be assessed.A clear lead discontinuity is visible, near the clavicle.A sharp angle is visible in the chest near the generator block connection and in that area, the lead appears to be twiddled.Based on the x-ray image, the cause for low impedance could be a short circuit in the lead part that appears to be twiddled.Further information was received from the nurse, indicating that no loss of efficacy yet but the patient recently could not perceive stimulation in magnet or normal mode.It was reported that no trauma was noted.The nurse indicated that it's unlikely that twiddling occurred as the generator is fairly deep and under a large breast.It was reported that the patient suffers from anxiety.Review of manufacturing records confirmed that both, the generator and the lead, passed all functional tests prior to distribution.No known surgical interventions have been performed to date.
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