| proSA - description |
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The proSA is the first hydrocephalus valve
that enables post-operatively the adjustment of the opening
pressure in the upright position, as
well as for all angles of elevation between
the upright and the supine positions. This
opening pressure depends on the body
position of the patient. In addition to the proSA, a differential pressure valve (such
as the miniNAV) or a programmable valve
(such as the proGAV) should be implanted. |
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Fig.1 shows a schematic cross section of
the proSA.
The proSA is composed of a robust titanium
casing whose proximal end contains
a ball-cone valve. A coil spring (1) determines the opening
pressure of the ball-in-cone valve and the
sapphire ball (2) ensures the precise closure
of the valve.The weight (4) is connected
to the spring and keeps the sapphire ball
in its position. In this way, optimal CSF
drainage is ensured for each individual
patient in any body position.
The tension of the spring, and thus the
valve opening pressure, can be adjusted
by turning the rotor (3) magnetically, with the valve implanted
under the patient’s skin.The cerebrospinal fluid
flows in through the inlet port (5) and flows
out by way of the outlet port (6). |
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| Horizontal position |
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| With the proSA in horizontal position (Fig.
2 and 3), the weight (4) does not affect the sapphire
ball. Hence, in this configuration the proSA is open, and the force brought to
bear by the weight does not counteract
the fluid pressure. The ventricular pressure
is now controlled solely by the optional differential pressure
valve installed (Fig. 3). |
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| Vertical position |
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In the vertical position, the proSA and the
differential-pressure valve work together.
The total opening pressure is the sum of
the opening pressures of the DP-valve
and the proSA. If the IVP (intraventricular
pressure) of the patient and the hydrostatic
pressure exceed this pressure, the closing
ball of the proSA is pushed away from the
cone seal and a gap opens for fluid drainage
(Fig. 4). The valve system prevents increases
in intraventricular pressure above
the physiological range.
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