MIETHKE GAV, Patient Handbook

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| PATIENT HANDBOOK
GB
1 ventricle container
2 ventricle
3 drainage tube
4 abdominal cavity
5 abdominal container
6 accumulated water or blood
7 contracted ventricles
8 valve
Fig. 7: Ventricle drainage with conventional valve
a) horizontal, b) vertical
a) 1 2 3 4 5
x
b)
1
5
8
6
7
3
4
x
0
The following sketch demonstrates the importance
of implanting a valve that offers a significantly high-
er opening pressure for the vertical position (cor-
responding to the distance between the brain and
the abdomen) than for the horizontal position.
The
GAV is such a valve. It sets the required intra-
cranial pressure for the patient in every body po-
sition. The problems and complications described
above are avoided by preventing any unintentional
overdrainage of cerebrospinal fluid (fig. 8).
x = opening pressure in horizontal position
1 ventricle container
2 ventricles
3 drainage tube
4 abdominal cavity
5 abdominal container
6 GAV
Fig. 8: Ventricle drainage with GAV
a) horizontal, b) vertical
x
a) 1 2 3 4 5
2
3
4
0
1
6
5
b)
TECHNICAL SPECIFICATIONS OF THE VALVE
Fig. 9: Schematic cross section of the GAV
(see inner cover page)
a) ball-cone valve
b) gravity valve
1) coding ring
2) coil spring
3) tantalum ball
4) sapphire ball
The
GAV
uses gravity to adjust, regardless of the
patient’s position, a ventricular pressure guided by
pressure values as in a healthy person. A ball-cone
valve controls the ventricular pressure when the
patient is lying down. As soon as the patient rises,
a heavy tantalum ball is brought into action which,
through its gravity, adjusts the valve to a higher
opening pressure. The closer the upper body of
the patient gets to the vertical position, the higher