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Model Number 302-20 |
Device Problems
High impedance (1291); Device Inoperable (1663)
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Patient Problem
Seizures (2063)
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Event Date 06/12/2014 |
Event Type
malfunction
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Event Description
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It was reported that the vns patient¿s device was tested during an office visit on (b)(6) 2014 and system diagnostic results showed high impedance (dc dc ¿ 7).The patient¿s parent stated that she no longer heard the patient¿s voice alteration that normally occurred with stimulation.The patient went to the hospital on (b)(6) 2014 after having three generalized seizures the previous week.It was noted that a football hit the patient in the chest/clavicle the previous week.The physician stated that the reported event was related to vns stimulation.X-rays dated (b)(6) 2014 were provided to the manufacturer for further review.The generator appears in the left chest in a normal placement.The filter feed-through wires appear to be intact.The lead connector pin appears fully inserted into the generator connector block.The electrodes appeared to be placed in normal arrangement.Part of the lead was behind the generator and could not be assessed.No clear lead breaks or sharp angles were found in the parts of the lead that could be assessed.Based on the images provided, the cause of the high lead impedance remains unknown.Further follow-up revealed that the patient¿s device was disabled on (b)(6) 2014.The patient¿s seizures had changed in type and were longer.Prior to the event, the patient only had simple seizures.The patient underwent lead replacement surgery on (b)(6) 2014.The explanted lead has not been returned to date.The patient was doing well following lead replacement surgery.
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Event Description
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Additional information was received stating that the vns patient underwent lead replacement surgery due to lead discontinuity.The explanted lead was returned to the manufacturer for analysis.Based on the findings, there is evidence to suggest discontinuities in the returned portions of the lead may have contributed to the reported high impedance.During the visual analysis, quadfilar coil 1 appeared to be broken approximately 24mm from the electrode bifurcation.Scanning electron microscopy was performed on the connector end of the quadfilar coil 1 coil break and identified the area on two of the broken strands as being mechanically damaged which prevented identification of the coil fracture type and no pitting.The area on a third broken coil strand was identified as having evidence of a stress induced fracture with mechanical damage and no pitting.Determination could not conclusively be made on the fracture mechanism.The area on the remaining broken coil strand was identified as having evidence of a stress induced fracture (fatigue appearance) with mechanical damage and no pitting.Scanning electron microscopy was performed on the electrode (mating end) of quadfilar coil 2 coil break (found at 24mm) and identified the area as having extensive pitting which prevented identification of the coil fracture type with mechanical damage.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.Low magnification sem analysis of the quadfilar coil shows characteristics typical of a lead discontinuity.The abraded openings and slice mark 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.With the exception of the observed discontinuity 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 and no other discontinuities were identified.Note that since the (+) white electrode was not returned for analysis, an evaluation and resulting commentary cannot be made on that portion of the lead.
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Manufacturer Narrative
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Device failure occurred, but did not cause or contribute to death.
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Manufacturer Narrative
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Manufacturer reviewed x-rays of implanted device.Device manufacturing records were reviewed.X-rays reviewed by manufacturer, no gross lead discontinuities visualized.Review of manufacturing records confirmed that the lead passed all functional tests prior to distribution.Device failure is suspected, but did not cause or contribute to a death.
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Search Alerts/Recalls
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