During generator replacement surgery high lead impedance was observed after a new generator was connected to the existing lead.It was reported that no diagnostics were performed prior to surgery.It was reported that several diagnostics were performed after ensuring that the lead pin was fully inserted into the generator header; however, the high impedance remained.The surgeon reported that he saw a kink in the lead along with fluid in the tubing.The lead was explanted and a new lead and generator were then implanted.The explanted lead and generator were received for analysis.Analysis of the generator was completed on (b)(4) 2014.The generator performed according to functional specifications.During the product analysis there were no anomalies found with the pulse generator.Analysis of the lead is underway, but has not been completed to date.
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Additional information was received stating that there was no patient manipulation and trauma that could have caused a lead break.It is uncertain if diagnostic testing was completed prior to surgery.The patient is only seen once a year by the office and is currently doing well.The surgery was prophylactic, and the high impedance was discovered at surgery.Analysis of the returned lead portions was completed.During the visual analysis abraded openings were observed on the outer silicone tubing and on one of the inner silicone tubes.The lead assembly had dried remnants of what appear to have once been body fluids inside outer and inner silicone tubes, in some areas.During the visual analysis of the returned 46mm portion quadfilar coil 1 appeared to be broken approximately 10mm and 16mm from the end of the cut outer / inner silicone tubes.Scanning electron microscopy was performed and identified the coil break areas as having evidence of a stress induced fracture (fatigue appearance) with mechanical damage and no pitting.During the visual analysis of the returned 46mm portion quadfilar coil 2 appeared to be broken approximately 16mm from the end of the cut outer / inner silicone tubes.Scanning electron microscopy was performed and identified the area on one of the broken coil strands as having evidence of a stress induced fracture (fatigue appearance) with mechanical damage and no pitting.The area on the remaining broken coil strands was identified as being mechanically damaged which prevented identification of the coil fracture type with no pitting on two and pitting on one of the coil strands.Pitting was observed on the coil surface.It is believed that stimulation was present for a certain period of time as evidenced by the presence of metal pitting.The slice marks and abraded openings found on the outer silicone tubing, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids inside the outer silicone tubing.For the observed inner silicone tubing 1 fluid remnant, there was no obvious path for fluid ingress other than the cut ends that were made during the explanted process.The abraded opening found on inner silicone tubing 2, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids inside the inner silicone tubing.With the exception of the observed discontinuities, the condition of the returned lead portions is consistent with conditions that typically exist following an explant procedure.No other obvious anomalies were noted.The setscrew marks found on the lead 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, and no other discontinuities were identified.Based on the findings, there is evidence to suggest a discontinuity in the returned portions of the device which may have contributed to the reported high impedance.Note that since a portion of the lead assembly including the electrode array section was not returned for analysis, an evaluation cannot be made on that portion of the lead.
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