| 摘要 |
<p>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, one side of which is in the pressure communication with the drainage location of the body, and the other side of which is in pressure communication with the ventricular spaces of the brain. A valve assembly, actuable by displacement of the diaphragm in response to applied pressure differentials, regulates passage of CSF from the ventricular spaces to the drainage location. When the pressure differential falls below a minimum threshold level, the valve is closed to prevent fluid flow. When the pressure differential increases beyond the threshold, the valve operates in a constant pressure mode to maintain a first predetermined pressure differential across the valve. In response to an increase in differential pressure beyond an intermediate threshold level, the valve mechanism operates in a constant flow mode to maintain a desired relatively constant CSF flow rate through the valve. Above a predetermined maximum pressure differential, the valve operates in a constant pressure mode to maintain a second predetermined maximum pressure differential across the valve. To provide for adjustment of the flow characteristics of the valve in the various modes, the valve stem is provided with multiple adjustment means.</p> |
