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| INSTRUCTIONS FOR USE
GB
1 Micro spiral spring
2 Tantalum ball
3 Sapphire ball
4 Coding
1
2
3
4
Fig. 1: GAV 2.0 in cross section
INDICATION
The GAV 2.0 is used for cerebrospinal fluid (CSF)
drainage in the treatment of hydrocephalus
TECHNICAL DESCRIPTION
GAV 2.0 is a valve made from titanium. It con-
sists of a ball-cone unit and a gravitational unit.
Thus a physiological intraventricular pressure
(IVP) can be reached in any body position.
In the proximal part of the GAV 2.0, micro spiral
spring (1) enables the opening pressure of the
ball-cone unit. The gravitational unit in the distal
part of the valve consists of a tantalum ball (2)
which defines the opening pressure of this unit,
and a sapphire ball (3) which enables its precise
closure. Coding (4) permits the identification of
pressure levels in an X-ray.
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GAV 2.0
FUNCTION OF THE VALVE
The GAV 2.0 is a position-dependent valve.
Horizontal position
In the horizontal position, the gravitational unit
is always open and does not present any resi-
stance. For that reason, the GAV 2.0 opening
pressure in this position is only defined by the
ball-cone unit. Fig. 2a shows the ball-cone unit
in closed status. If the patient's intraventricular
pressure (IVP) exceeds the opening pressure of
the micro spiral spring, the ball from the cone,
thus opening a gap for drainage (Fig. 2b).
a)
b)
Fig. 2: GAV 2.0 in horizontal position
a) closed b) open
GAV 2.0
Vertical position
When the patient moves into an upright posi-
tion, the gravitational unit is activated and the
opening pressure of the GAV 2.0 is significantly
increased (Fig. 3a). In addition to the opening
pressure of the ball-cone unit, the weight of the
tantalum ball (opening pressure of the gravitati-
onal unit) has to be exceeded. Drainage is only
possible once the sum of intraventricular pres-
sure (IVP) and hydrostatic pressure is greater
than the opening pressure of both units (Fig. 3b).
a)
b)
Fig. 3: GAV 2.0 in vertical position
a) closed b) open
INSTRUCTIONS FOR USE |
SELECTION OF THE
APPROPRIATE PRESSURE LEVEL
Horizontal position
Depending on the clinical picture and age of the
patient, the opening pressure for this position
can be selected between pressure levels 5 and
10 cmH
O.
2
Vertical position
Patient size, activity level and potentially incre-
ased abdominal pressure (obesity) should be
taken into account in selecting the opening
pressure for this position (see pressure level re-
commendations at https://www.miethke.com/
en/products/downloads/).
PRESSURE LEVELS RECOGNITION
IN X-RAY IMAGES
The selected pressure levels can be detected
radiographically after implantation.
Valve opening pressure
Coding
horizontal
vertical
5 cmH
O
20 cmH
O
2
2
5 cmH
O
25 cmH
O
2
2
5 cmH
O
30 cmH
O
2
2
5 cmH
O
35 cmH
O
2
2
10 cmH
O
25 cmH
O
2
2
10 cmH
O
30 cmH
O
2
2
Fig. 4: GAV 2.0 pressure levels encodings on X-ray
GB
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