DREISTUFIGES VENTIL ZUR REGELUNG DES INTRAKRANIALEN DRUCKES.

摘要

An implantable valve for controlling the passage of cerebrospinal fluid (CSF) from a ventricle of the brain to a suitable drainage location in the body includes a movable diaphragm which positions a valve seat in response to the pressure differential between the inlet and outlet of the valve. The valve seat defines a fluid orifice. An improved valve stem, preferably of one-piece construction, and provided with a series of cooperating diverging and converging frusto-conical portions, extends through the orifice to provide four stages or conditions of fluid flow and pressure control in response to relative movement between the valve seat and stem. In a first stage or condition of operation of the valve, wherein the fluid pressure differential falls below a threshold level, fluid flow is prevented. In a second stage, sufficient fluid flow is permitted to maintain a first substantially constant predetermined differential pressure. In a third stage, fluid flow through the valve is maintained at a substantially constant rate, and in a fourth stage sufficient fluid flow is permitted to maintain a second substantially constant predetermined differential pressure.