On (b)(6) 2014, it was reported that the patient was referred for generator replacement due to battery depletion and that prior to the replacement, system diagnostics were performed on the existing generator and results were normal.However, when the new generator was attached to the leads, the impedance was high.The lead was disconnected and re-inserted, and the impedance was high again.The test resistor was connected to the generator and the impedance was normal.The physician re-attached the generator to the lead and the impedance was then low.A new generator was then connected to the lead and the impedance was high again.The physician therefore replaced the lead as well.The explanted lead and generator were received for product analysis on (b)(6) 2014.Product analysis is still underway and has not yet been completed.
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On (b)(4) 2014, product analysis was completed on the lead which confirmed opening of both inner tubing sections in adjacent areas, exposing conductive quadfilar coils and creating a potential short-circuit condition.Small portions of the (+) white and (-) green inner silicone tubes and quadfilar were not returned for analysis; therefore, a complete evaluation could not be performed on the entire lead product.During the visual analysis of the returned 31mm portion, abraded openings were observed on both of the inner silicone tubes, past the electrode bifurcation, and both of the quadfilar coils appeared to be exposed.During the visual analysis of the returned 3mm portion the (+) white electrode ribbon appeared to be embedded in what appeared to be remnants of dried body tissue.This condition may have prevented the (+) white electrode ribbon from coming in contact with the vagus nerve.The abraded opening found on the outer silicone tubing and the cut ends that were made during the explanted process, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids inside the outer silicone tubing.With the exception of the observed tissue-covered (+) white electrode ribbon and the inner tubing abraded openings, the condition of the returned lead portions is consistent with conditions that typically exist following an explant procedure.No other obvious anomalies were noted except for the half sets of setscrew marks found near the end of the connector pin indicating the lead had not been fully inserted into the cavity of the generator at one time.Additional setscrew marks found on the connector pin provide evidence that, at one point in time, a good mechanical and electrical connection was present.Continuity checks of the returned lead portions were performed, during the visual analysis, with no discontinuities identified.The positive electrode condition may have contributed to the reported high impedance.Product analysis was completed on the generator on (b)(4) 2014.The end of service condition was determined to be the result of normal battery depletion.The depletion was an expected event as determined by blc and battery voltage measurement.The module performed according to functional specifications; there was no condition noted during the product analysis evaluation that would suggest any anomaly with the device.
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