The principle of the Sophy® and Polaris® adjustable pressure valves is based on the pressure variation exerted on a ball by a flat semi-circular spring at various points of its curvature. At each contact point of the spring with the ball, corresponds a resistance or differential pressure.
The ball-in-cone mechanism situated at the extremity of the inlet connector, ensures a perfect anti-reflux function and is insensitive to temperature variations.

Tests have demonstrated that Sophy® and Polaris® valves did not exhibit any reflux for outlet-inlet differential pressure of up to 200 mmHg, i.e. more than 2700 mmH2O.

The spring is connected to a magnetic rotor whose position can be modified non-invasively by using an adjustment magnet.

The rotor of Polaris® features a patented self-locking mechanism which prevents unintentional dysadjustment during everyday life and MRI exposure.

The chamber of the valve :	Polysulphone
The ball :	Synthetic Ruby
The valve connectors :	Medical grade 316 L stainless steel
The 2 micro-magnets of the valve rotor :	Samarium Cobalt

Sophysa Adjustable Pressure Valves are latex free. Catheters included in Sophysa shunt kits are made of silicone.

All along the pressure range of the SM8 and SPV models, the precision of calibration is within -10/+15 mmH2O from the nominal value. The flat semi-circular spring ensures a precise and reproducible functioning pressure for each position of the rotor. It is resistant to ageing and maintains constant performance over time.

Sophy® adjustable valves
- 50, 110, 170 mm H2O for the model SM3
- 30, 50, 70, 90, 110, 140, 170, 200 mm H2O for the model SM8
- 50, 75, 100, 125, 150, 180, 220, 300 mm H2O for the model SM8-300
- 80, 120, 150, 190, 230, 270, 330 400 mm H2O for the model SM8-400
- 10, 25, 40, 60, 80, 100, 120, 140 mm H2O for the model SM8-140

Polaris® adjustable valves
- 30, 70, 110, 150, 200 mm H2O for the model SPV
- 50, 100, 150, 220, 300 mm H2O for the model SPV-300
- 80, 150, 230, 330, 400 mm H2O for the model SPV-400
- 10, 40, 80, 110, 140 mm H2O for the model SPV-140

The Sophy® and Polaris® valves are stiff, because the mechanism has to be protected against shock, pumping operations or needle punctures. Nevertheless its anatomic shape is especially adapted to the skull's convexity.
This non-distorting structure is insensitive to subcutaneous pressure variation, unlike silicone valves.

Yes. It will have to be placed distally to the valve and the valve should be set towards the lowest pressures.

The On-Off systems available on the market do not avoid the risk of an accidental closure.

It is advisable to adjust the valve before implantation.

Before opening the sterile packaging, place the rotor in the position selected for implantation, by placing the adjustment magnet over the valve in the position of the packaging shell designed for this purpose, with its north pole placed to the left of the direction of the flow. Turn the magnet in order to adjust the rotor to the desired position.

This pre-implantation adjustment avoids contact with the scar of the implantation site, reduces the risk of infection and ensures better patient comfort.

No. As each valve has been individually calibrated and controlled with specific high precision equipment, it is unnecessary to perform any additional tests prior to implantation.

Per-operative testing increases operating time and infection risk and thus should be avoided.
Neurosurgeons that use regularly the Sophy® and Polaris® adjustable pressure valve have now evidence of the reliability of the valve.

1. Sophy® or Polaris® have to be thoroughly flushed from air bubble, either with the patient CSF or with sterile water.
2. The depth of implantation MUST NOT exceed 10 mm below the skin surface for Sophy® and 8 mm for Polaris®.
3. Before closing the implantation site, the arrow moulded on the upper surface of the Sophy® and Polaris® MUST be visible and MUST point the flow direction of the CSF.

More and more neurosurgeons advocate initial pressure setting toward highest pressure whatever the etiology in order to reduce the risk of overdrainage related complications :

Miyake et al., in Neurosurgery, Vol. 40, No. 5, May 1997

« Our strategy for the initial setting of the programmable valve may have also contributed to the favorable results. We set the initial pressure at the highest level below the preoperative ICP, which may have decreased the incidence of overdrainage-related complications, even in patients with with high pressure hydrocephalus. »

Lee et al., in Child’s Nerv Syst (2002), 18:533-563

« The use of programmable shunt devices has been strongly recommanded for all types of hydrocephalus and especially for NPH, but vigorous efforts should be invested in finding the optimal pressure for each patient to get the best results from shunting. Our suggestion for adjustment is to set the initial valve pressure at a level 10-30 mm H2O lower than their CSF pressure and decrease the pressure by 30 mm H2O every 3 weeks (could be shortened to 1 or 2 weeks, depending on symptoms or CT findings) until the symptoms have improved and the ventricles have normalized. We have found that this method is effective and safe in reducing the risk of complications related to overdrainage syndrome. »

Yes, it is. The Sophy® valve placed on the flank region should be fixed over a bony surface like lower ribs in order to facilitate its localiation for adjustment. The catalog number for a complete lumbo-peritoneal Sophy® shunt kit preattached is SM8-2040.

Polaris® valve is contra-indicated for lumbo-peritoneal shunting, since the depth of implantation is likely to exceed 8 mm from the skin surface.

The Sophy® valves can be implanted either on the skull or in the infra clavicular fossa without any difference in the flow regulation and drainage performances.

In case of chest implantation, the valve should be sutured, by using the integrated fixation holes, to the underlying fascia in order to prevent valve rotation on its axis.

Polaris® valve is contra-indicated for chest implantation since the depth of implantation is likely to exceed 8 mm below the skin surface.

The main pressure settings of the Sophy® adjustable pressure valve can be easily determined both visually and radiographically by means of a standard identification code. From the inlet connector, on the right side of the valve is a sequence of one, two and three dots corresponding to the 3 main pressure settings.

When the right micro-magnet of the rotor is opposite :
  - One dot                = Low pressure setting
  - Two dots           = Medium pressure setting
  - Three dots     = High pressure setting

The intermediary pressure settings can be assessed by the position of the right micro-magnet in relation to the dots.

Each pressure setting of the Polaris® adjustable pressure valve can be easily determined both visually and radiographically. From the inlet connector, on the right side of the valve is a sequence of 5 dots, each dot corresponds to one of the 5 pressure settings.
When the right micro-magnet of the rotor is opposite :

- To nearest dot from the inlet connector = Lowest pressure setting (N°1)
- To the furthest away dot from the inlet connector = Highest pressure setting (N°5)

The presence of one, two or three radio-opaque dots, or alternatively, the absence of a dot, to the left of the inlet connector, allows the pressure range of the valve to be identified, both visually or radiographically :

   - No dot   : Nominal maximum pressure of 140 mm H2O
   - One dot   : Nominal maximum pressure of 200 mm H2O
   - Two dots   : Nominal maximum pressure of 300 mm H2O
   - Three dots   : Nominal maximum pressure of 400 mm H2O

The operating pressure range for each Sophy® or Polaris® valve is detailed on the accompanying Patient Identification Card, in accordance with the model of the implanted valve.

A valve implanted on the right side of the skull is correctly placed if the radio-opaque dots indicating the pressure settings are pointing towards the patient's nose.

A valve implanted on the right side of the skull is incorrectly placed (upside down) if the radio-opaque dots indicating the pressure settings are pointing towards the patient's neck.

1. The direct reading with the compass will be inverted : a pressure setting in LP will be read HP with the compass; a pressure setting HP will be read LP.
   
2. For adjustment, the north pole of the magnet will have to be placed to the right of the direction of the flow.

By experience the main reasons can be listed as follows:

1. Unsuitability of the adjustment kit with the implanted valves.
   Be sure that the Sophy® adjustment kit (Cat. Nb = RS5) is used for a Sophy® valve, and a Polaris® adjustment kit (Cat. Nb = PAK) is used for a Polaris® valve.
   
2. Incorrect manipulation of the adjustment kit ( see IFU).
   
3. The valve has been implanted upside down.
   Check on the X-ray the correct implantation of the valve (see questions N°10, N°11 and N° 17, N°18).
   
4. Valve implantation is too deep beneath the skin surface.
   At the time of implantation, the depth below the skin should not exceed 10 mm for Sophy® and 8 mm for Polaris® valve.
   
5. The rotor of the valve is blocked by biological deposit.

Yes. A ventricular catheter with a reservoir or a valve with integrated reservoir is necessary to check the patency of the shunt.

Yes. This is quite frequent and whatever the disturbance it may cause, it also means that the shunt is functioning well.

The reason for this is the rotation of the ruby ball on its seat and the turbulence induced by CSF flow through the rigid structure of the valve. These noises are amplified and transmitted by the skull to the cochlea.

These noises mainly occur when the patient is changing position leading to a temporary increase of the CSF flow through the shunt.

1. The pressure setting of the Sophy® adjustable valve may be altered when exposed to strong magnetic fields. It is important to mention that this is true for other types of adjustable pressure valves on the market, EXCEPT Polaris®.
   Outside the 0.5 mT safety line, which encircles the MRI scanner, there is no disadjustment.
   The Polaris® adjustable pressure valve is the ONLY adjustable pressure valve with no disadjustment while exposed to a strong magnetic field such as 3 Tesla MRI.
   
2. The micro-magnets included in every adjustable pressure valves are responsible for the artefacts on the images. The artefacts induced by Sophy® and Polaris® valves are similar. If critical areas during the follow-up of the patient are expected to be obscured by artefacts, knowledge of the expected degree of signal void and image distortion may influence surgical decision regarding site of implantation.
   
3. There is no damage of the Sophy® and Polaris® valve mechanism even after multiple MRI exposure, meaning that the Sophy® and Polaris® valves remain adjustable. This has been demonstrated with exposure to 3 Teslas.

NO !!!

cf : study of Ortler, Neurosurgery, Vol.40, No 5, May 1997 :

"… the force acting on the valves during MRI is not strong enough to dislocate or rotate a valve."
"… the torque acting on a Sophy® Valve corresponds approximately to the torque acting on a Mc Fadden aneurysm clip."

No heating effect at the valve fixation site has been experienced by volunteers.

The operating pressure does not correspond to intracranial pressure, but is only the resistance of the valve to CSF flow. Catheters also add resistance to the CSF flow.

Drainage occurs as a result of positive pressures (intraventricular pressure or ICP, weight of the height of the CSF column) and negative pressures (cerebral resistance to flow / poor compliance, valve operating pressure, catheters length and diameter, intra-abdominal pressure*). Thus there is no evidence that the ICP should have the same value as the operating pressure of the valve.

*in case of a ventriculo-peritoneal shunt

The symptoms described are probably related to overdrainage.

The absence of slit ventricles on a CT scan could suggest that this is not the case, but in the presence of contradicting signs/symptoms, decisions should always be based on the clinical signs. The development of clinical signs often precedes the effects of overdrainage on ventricular volume and therefore the appearances seen on a CT scan.

In the case described, we would therefore increase the valve operating pressure (moving from medium pressure = 110 to high pressure = 200) in order to reduce drainage and we would monitor changes in the patient's symptoms and, if necessary set later the valve to an intermediary pressure.

Development of a sub-dural haematoma in a patient with hydrocephalus carrying a shunt probably indicates a well-known side effect, which is a consequence of overdrainage.

A CT scan would probably show slit ventricles.

In the case described the valve is set to 70 mm H2O. This is a relatively low operating pressure and we would therefore recommend to increase the valve pressure. The neurosurgeon could also decide immediate drainage of the heamatoma , depending on the patient's condition.

The slit ventricle syndrome is due to overdrainage, the major risk of which is development of a sub-dural haematoma.

We would therefore increase the valve pressure.

In the case described, the valve is set to 200 mm H2O, the maximum pressure for an SM8 or SPV valve. It is therefore impossible to increase the pressure of this valve and it will therefore have to be replaced by a specific SM8 or SPV valve with an operating pressure of up to 300 (SM8-300, SPV-300) or even 400 mm H2O (SM8-400, SPV-400).

Magnetic fields generated by airport security doors, microwave oven, mobile phone, high tension wire, TV, etc..., can potentially alter the pressure setting of the Sophy® valve.

The permanent magnets, domestic, in toys, in audio headphones, in loud speakers, and electromagnetic field created by electric motor from shaver, hair dryer, clipper, while turned on, etc…can also modify the Sophy® pressure setting. Thus in order to prevent any risk of pressure alteration, they must not be brought close to the valve site.

Direct shocks on the implanted site of the valve can also be responsible of disadjustment.

It is important to mention that this is true for the other types of adjustable pressure valves on the market, EXCEPT Polaris®.

The patented Self-locking System of the Polaris® adjustable pressure valve makes it insensitive to any everyday magnetic fields unintentionaly approached and also to direct shocks.

Using an external drainage system with a valve should be avoided. In case of temporary externalisation of a ventriculo-atrial / peritoneal shunt with a valve, the follow-up is identical to a conventional external drainage. It will have to be performed by people having the necessary skills and under the responsibility of a physician.

There are no contra-indications for laparoscopy on patients with Sophy® or Polaris® valves: Inflating CO2 pressure ranges from 10 to 15mmHg, which is far below the anti-reflux performance of valves tested up to 200 mmHg.

However, the shorter the laparoscopic surgery the better, since the abdominal pressure will reduce the ventriculo-peritoneal drainage during inflating.

It can also be recommended to decrease the pressure setting of the adjustable valve during surgery.

All the Sophy® and Polaris® valves are manufactured with an individual serial number etched on the inferior face of the valve casing.

Moreover, each Sophy® and Polaris® valve is packaged with a Patient Identification Card (PIC) and a set of stick-on labels mentioning the Cat. Number, Lot Number and Serial Number.

The PIC should be carried by the patient at all times, providing the information of the implanted device (reference, pressure setting, …).

No. Our products are sterilised with ethylene oxide. They are for single use only and must not be re-sterilised or used if the packaging is opened or damaged, or beyond the expiry date.

If the packaging has been opened and the valve unused, it has to be returned to SOPHYSA for re-sterilisation.