(b)(4).The valve was returned for evaluation.Visual inspection of the valve found that the stator, x-ray dot and pivot were dislodged.Due to this, the programming and pressure tests could not be performed.The valve was leak, flush and reflux tested, with no issues found.The valve was then dismantled and evaluated at appropriate magnification.Bump marks were noted in the valve casing.This is likely due to the valve receiving a hard knock.Corrosion was found on the stator and x-ray dot.The lot history record for product was reviewed for completeness during the release process to inventory.No issues were found when the device was released to stock.Investigation of the returned device confirmed the issue reported by the customer.While root cause could not be conclusively determined, it is likely that the dislodged stator and corrosion was due to the valve receiving a hard knock.Stator dislodgement of chpv was investigated through a previous investigation.The investigation concluded that several factors may contribute to the stator dislodgement.Trauma to the valve, whether it occurs while implanted or at explant, was the root cause of stator dislodgement.Galvanic corrosion could not be established as a direct root cause for those valves investigated, however it was found to be a contributing factor when trauma to the valve was found.Corrosion, when it arises, only arises after long term exposure to csf.-this issue will continue to be monitored through monthly complaint trending and the post market surveillance process.Trends will be monitored for this or similar complaints.At present, we consider this complaint to be closed.
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