Unique device identifier (udi) : (b)(4).The certas valve was returned for evaluation: device history record (dhr) - lot 4131217, conformed to the specifications when released to stock on the 4th november 2019.Failure analysis - the valve was visually inspected, no defects were noted.The valve passed the test for programming, occlusion, leaks, reflux, siphon guard and pressure.No root cause could be determined as the technician could not confirm any problem with the valve at the time of investigation.The possible root cause for the issue reported by the customer could be due to an excessive flow rate (>0.75 ml/min) during the flushing procedure activates the siphon guard and creates the impression that the valve is distally occluded.In reality the flow is being diverted to the high resistance secondary pathway, this will slow the rate at which csf is shunted from the brain.It would probably explain the problem encountered by the customer.
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