It was reported the lead was found encapsulated by calcification at the site of the vns generator.When the generator was removed from the pocket, the lead was found to be damaged.Due to the lead damage, the lead was replaced.It was reported the vns device was tested during the pre-operative evaluation and no high impedance was noted.The suspect device is expected to be returned, but has not been received to date.
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Product analysis for the returned lead was completed.It was noted that a portion of the lead assembly, including the electrodes, was not returned for analysis.White deposits were observed in various locations.The deposits were analyzed with energy dispersion spectroscopy which identified silicon, phosphorus, sodium, magnesium, and calcium.During visual analysis, three areas of the coil strands were identified as having the appearance of being melted, with re-solidified material.Based on obvious signs of mechanical damage on the coil surface, it is possible the thermally-damaged coil was exposed to a high temperature device such as a cauterizing tool during the explant of the lead.There were also two stress-related fractures noted on the lead.The stress fractures were due to rotational forces, which most likely completed the fracture with mechanical damage.A third region of the coil appeared to be stretched, kinked, and extended past the end of the cut/torn outer and inner silicon tubes.Determination could not be made if the end was cut.The condition of the returned lead portion is consistent with conditions that typically exist following an explant procedure.No other obvious anomalies were noted except for the set of setscrew marks found near the end of the marked connector pin, indicating the lead had not been fully inserted into the cavity of the generator at one time.However, additional setscrew marks found on the connector pin provide evidence that, at one point in time, a good mechanical and electrical connection was present.The setscrew marks on the unmarked 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 discontinuity was identified.Based on the findings in the product analysis lab, there is no evidence to suggest a discontinuity in the returned portions of the lead.
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