Hydrocephalus shunt device - comprises membrane valve in housing, inlet connecting, outlet connecting to abdominal catheter

摘要

A valve membrane (6) is fitted between the inlet and outlet (3) apertures. A spring plate (8) and a tension device (6,13,14) tension the membrane against a valve seat (5) with a predetermined force. The valve seat, in which the outlet aperture issues, is arranged centrally to the membrane. The valve only opens when pressure in the lateral ventricle, and therefore that on the membrane, the predetermined pressure. Opening of the valve can take place despite the powerful tensionpressure, because the force acting in the shunt proximal part acts on the membrane surface which is considerably larger in relation to the surface subjected to suction forces, or siphon effect, from the distal part of the shunt. A constant pressure is maintained in the proximal part of the shunt independent of the pressure ruling in the shunt distal part.