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Investigation: visual inspection: a deformation of the outer housing of the progav valve and deposits on the catheter between the valves were observed through the visual inspection.The measurement of the plane parallelism could confirm that with a value of 0,052 mm the housing membrane is clearly outside tolerance (0 ± 0.02 mm).Permeability test: a permeability test has shown that both valves are permeable.Computer controlled test: to investigate the claim of over-drainage, the opening pressure is measured using a miethke computer controlled testing apparatus which simulates a cerebrospinal fluid flow.The valves are tested in both the horizontal as well as the vertical positions.The results show that the progav is operating within the accepted tolerance in the horizontal position.The shunt assistant is operating not within the specified tolerances in the vertical position.An accelerated outflow could be determined.Adjustment test: the progav was tested and is adjustable to all specified pressures.Braking force and brake function test: the brake functionality test has shown that the brake function is fully operational and the braking force is within the given tolerances.Internal inspection : after dismantling of the valves, deposits were found in both valves.Results: for the sake of thoroughness and transparency, we would like to point out that a permeability test and adjustability test were already carried out after the revision at the hospital.Based on our examination results, we are able to determine an accelerated outflow of the shunt assistant.This is likely due to the deposits observed inside the valves.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 shunt system 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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