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Same event: mdr#3004721439-2021-00148.Investigation: visual inspection: no significant deformations or damage of the shuntassistant were detected during the visual inspection.The returned valves were connected with a bactiseal catheter.Permeability test: a permeability test has shown that the valve is permeable.Computer controlled test: to investigate the claim of under-drainage, the opening pressure is measured using a miethke computer controlled testing apparatus which simulates a cerebrospinal fluid flow.The results show that the valve is not operating within the acceptable tolerance in the vertical position.Results: first, we performed a visual inspection of the shuntassistant.No significant deformations or damage of the valve were detected during the visual inspection.Next, we tested the permeability and opening pressure of the valve.The opening pressure of the valve was out of tolerance, but all other specifications were met.The measured values show a slightly accelerated outflow.Finally, we have dismantled the valve.Inside the valve we have found a build-up of substances (likely protein).In advance, we would like to point out that the permeability test has already been done after the revision on clinic part.Based on our test results, we can detect accelerated outflow at the shuntassistant at the time of our investigation.We suspect that the deposits found inside the valve have led to the functional impairment.As described in scientific literature, the problem encountered is one of the known, inevitable risks of hc-therapy by shunt implants.We can exclude a defect at the time of release.The valve met all specifications of the final inspection when released from christoph miethke gmbh & co.Kg.No further regulatory actions are required from our point of view.
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