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Model Number 304-20 |
Device Problem
High impedance (1291)
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Patient Problem
No Known Impact Or Consequence To Patient (2692)
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Event Date 11/10/2015 |
Event Type
malfunction
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Manufacturer Narrative
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(b)(4).
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Event Description
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It was reported that the patient was receiving an initial implant on (b)(6) 2015.During the surgery, high impedance was detected on the new vns system.The lead pin was disconnected and reconnected to the generator several times with additional diagnostic tests resulting in high impedance.A new lead was then opened and attached to the vagus nerve.When the new lead was connected to the generator, diagnostics again resulted in high impedance.The test resistor pin was then placed in the generator, but again diagnostics resulted in high impedance.A new generator was then opened and connected to the second lead.The subsequent diagnostic test resulted in a normal impedance value of 1,214 ohms.The surgery was then completed with these second devices implanted.The opened but unused generator and lead have not been received by the manufacturer to date.No additional relevant information has been obtained to date.
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Event Description
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Additional information was received that diagnostics were reportedly performed as opposed to just interrogations during the implant surgery where high impedance was detected.The explanted generator and lead were received by the manufacturer for analysis.Analysis of the suspect generator yielded no observed anomalies.The generator performed according to functional specifications.Various electrical loads were attached to the generator and results of diagnostic tests demonstrate that accurate resistance measurements were obtained in all instances.Review of the ram/flash data downloaded from the generator shows the increased impedance was corrected; from a value of 12258 ohms to a value of 4015 ohms, and the time of change detection was (b)(6) 2015 (date of implant).This is indicative that diagnostics performed with the test resistor indeed resulted in normal diagnostic values.Analysis of the returned lead has not been completed to date.No additional relevant information has been received to date.
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Event Description
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Analysis of the returned lead was completed.A bent pin was identified in the lead connector.The identified bend of the connector pin may have been a contributing factor for the reported high lead impedance.However, the exact point in time of when this condition occurred is unknown.No other anomalies were identified in the returned lead.Programming history was reviewed for this patient and identified that only one system diagnostics test was completed during implant, which indeed resulted in high lead impedance.However, once the next lead was implanted, only interrogations were performed which continued to report the stored high lead impedance, without actually re-assessing the actual impedance.No additional relevant information has been received to date.
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Search Alerts/Recalls
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