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Investiation: visual inspection: a deformation of the outer housing of the progav valve and a calcified catheter between the valves was observed through the visual inspection.The progav valve housing was subsequently measured and confirmed the presence of a deformation.The housing deformation measured at -0.055 mm, outside the tolerance of 0 ± 0.02 mm permeability test: a permeability test has shown that both valves are permeable.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.Computer controlled test: to investigate the clinical claim of underdrainage, the opening pressure is measured using a miethke computer controlled testing apparatus which simulates a cerebrospinal fluid flow.Both valves are operating within acceptable tolerances.Results: first, we performed a visual inspection of the progav shunt system.A deformation of the outer housing of the progav valve was observed through the visual inspection.The deformation was confirmed through a measurement of the parallelism of the valve housing.Additional was a calcified catheter detected.Next, we tested the permeability, adjustability, and opening pressure of the valve, as well as the brake functionality and brake force.The valve operates as expected and met all specifications.Finally, we have dismantled the valves.Inside the progav valve we have found build-up of substances (likely protein), in the shuntassistant are minimal visible deposits.Based on our investigation, we are unable to substantiate the clinical claim of under-drainage and non- adjustability.At the time of our investigation, the valves were operating within the specified tolerances.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.The cause of the deformation of the progav valve could not be determined through our investigation.Significant outside pressure, for example by too much force from the progav adjustment tool or by a fall or impact to the head of the patient, can compromise the integrity of the valve.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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