Importance

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Abstract

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 responsive to pressure differentials between the ventricle and the drainage location. When the pressure differential is below a minimum threshold level, the valve is closed and CSF flow is prevented. When the pressure differential increases beyond the minimum threshold, the valve operates in a constant pressure mode to maintain a first predetermined CSF pressure differential across the valve. When the differential pressure increases beyond an intermediate threshold level, the valve operates in a flow control mode to maintain a desired CSF flow rate through the valve. When the pressure differential increases beyond a maximum threshold level, the valve operates in a constant pressure mode to maintain a second predetermined CSF pressure differential across the valve. To provide for the various valve operating modes, the valve includes a valve stem and a valve closure member, which coact with a valve seat carried on the diaphragm. The valve closure member defines an annular valving surface which coacts with the diaphragm to provide improved fluid control at low differential pressures.

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First Claim