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What is the mechanism of the Sophysa Adjustable Pressure Valves?

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.
In addition, the rotor of Polaris® features a patented self-locking mechanism which prevents unintentional dysadjustment during everyday life and MRI magnetic fields.


Out of which materials are the Sophysa Adjustable Pressure Valves made?

Main component of the valve is polysulfone, the material of the chamber of the valve.
Besides this, the ball of the ball-in-cone mechanism is made out of synthetic ruby, the valve connectors, out of medical grade 316L stainless steel and the two micro-magnets of the valve rotor, out of Samarium-Cobalt.


What is the precision of the calibration of the Sophy® Mini and Polaris® Adjustable Pressure Valves?

All along the pressure range of the Sophy Mini and Polaris 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.


Why are the Sophy® and Polaris® valves stiff?

The Sophy® and Polaris® valves are stiff, because the mechanism has to be protected against shocks, 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.


Can we use an anti-siphon device with the Sophy® and Polaris® valves?

Yes. It will have to be placed distally to the valve and the valve should be set towards the lowest pressures.
SiphonX® is the anti-siphon device from Sophysa. SiphonX® is an gravitational anti-siphon device, which will act when the patient stands up. In the vertical position, it adds 200 mmH2O to the pressure of the valve.
SiphonX® is available as a stand-alone valve accessory, or can come directly pre-connected to a valve.


What about adjustment of the Sophy® or Polaris® valve before implantation?

It is recommended to adjust the valve before implantation because the adjustment procedure could be somehow difficult post-operatively, due to oedema and pain.
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's comfort.


Do you recommend a pressure test before implanting a Sophy® or Polaris® valve?

No. As each valve has been individually calibrated and controlled with specific high precision equipment, it is unnecessary to perform any additional testing prior to implantation
Per-operative testing increases operating time and infection risks and thus should be avoided.
Neurosurgeons who use the Sophy® and Polaris® adjustable pressure valve regularly have now evidence of the reliability of the valve.


Is there any precaution to be taken during the implantation procedure of the Sophy® or Polaris® valve?

Sophy® or Polaris® have to be thoroughly flushed from air bubbles, either with the patient CSF or with sterile water.
The depth of implantation MUST NOT exceed 10 mm below the skin surface for Sophy® and 8 mm for Polaris®.
In addition, the Polaris valve has to be implanted on a hard bony surface to allow future pressure adjustment.
Before closing the implantation site, the arrow moulded on the upper surface of the Sophy® and Polaris® must be visible and must point in the direction of the CSF flow.


Is there any recommended pressure setting for Sophy® or Polaris® at the time of implantation?

More and more neurosurgeons advocate an initial pressure setting toward the highest pressures whatever the etiology, in order to reduce the risks of over-drainage 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 high pressure hydrocephalus.»

Lee et al., in Child's Nerv Syst (2002), 18:533-563.
«The use of programmable shunt devices has been strongly recommended 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 H 2O 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 over-drainage syndrome.»


Is it possible to implant a Sophysa adjustable valve in a lumbo-peritoneal shunt?

Well, it depends on the type of valve! The Sophy® Mini valve can be used in a lumbo-peritoneal shunt. Sophysa even offers a complete kit, where the Sophy® Mini valve comes with the adequate catheters pre-attached (reference SM8-2040). The Sophy® Mini valve placed on the flank area should be fixed over a bony surface like lower ribs in order to facilitate its localization for adjustment. To the contrary, the Polaris® valve is contra-indicated for lumbo-peritoneal shunting, since the depth of implantation is likely to exceed 8 mm from the skin surface. Should it be used in a lumbo-peritoneal shunt, the Polaris® valve could be difficult to adjust afterwards.


Is there any difference in flow regulation between skull and chest implantation of a Sophy® valve?

The Sophy® valve can be implanted either on the skull or in the infra-clavicle fossa without any difference in the flow regulation or 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.
Chest implantation is contra-indicated for the Polaris® valve since the depth of implantation is likely to exceed 8 mm below the skin surface.


Is there any difference in flow regulation between skull and chest implantation of a Sophy® valve?

The Sophy® valve can be implanted either on the skull or in the infra-clavicle fossa without any difference in the flow regulation or 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.
Chest implantation is contra-indicated for the Polaris® valve since the depth of implantation is likely to exceed 8 mm below the skin surface.


How should one read the pressure setting of the Sophy® valve on X-Ray film?

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 there is a sequence of one, two and three dots corresponding to the 3 main pressure settings.
- One dot = Low pressure setting
- Two dots = Medium pressure setting
- Three dots = High pressure setting
The intermediary pressure settings can be determined by the position of the right micro-magnet in relation to the dots as shown in the pictures aside.


How should one read the pressure setting of the Polaris® valve on an X-Ray film?

Each pressure setting of the Polaris® adjustable pressure valve can be easily determined both visually and on X-Ray. From the inlet connector, on the right side of the valve is a sequence of 5 dots, each dot corresponding 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).


What does a radio-opaque dot to the left of the inlet connector to the Sophy® or Polaris® valve indicate?

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

- No dot: Nominal maximum pressure of 140 mmH 2O;
- One dot: Nominal maximum pressure of 200 mmH 2O;
- Two dots: Nominal maximum pressure of 300 mmH 2O;
- Three dots: Nominal maximum pressure of 400 mmH 2O.

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


From an X-ray, what is the method to be sure that an implanted Sophy® or Polaris® valve is correctly in place (engraved arrow on the skin side), or upside down (engraved arrow on the skull side), regardless of the side from which the X-ray film is read?

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.


What about adjustment if the Sophy® or Polaris® valve has been implanted upside down (arrow seated on skull side instead of skin side)?

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.
For the adjustment of the Sophy® Mini and of the Polaris® valve, the identified pole of the magnet will have to be placed to the right of the direction of the flow instead of its left.


What could be the main reasons for difficulty or failure of the pressure adjustment on an implanted Sophy® or Polaris® valve by a physician?

By experience, the following main reasons can be listed:

Unsuitability of the adjustment kit with the implanted valves:

Be sure that the Sophy® adjustment kit (Ref RS5) is used for a Sophy® valve, and a Polaris® adjustment kit (Ref. PAK or Ref PAK-2) is used for a Polaris® valve.
Incorrect handling of the adjustment kit:
- Please refer to the adjustment kit Instructions for Use or the details given in this Website to be sure to use the adjustment kit correctly.
- The valve has been implanted upside down:
- Check if the valve has been implanted correctly on the X-Ray (see questions above).
- Valve implantation site 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. In addition, Polaris® must have been implanted on a hard bony surface. Otherwise, pressure adjustment can be impaired.
- The rotor of the valve is blocked by biological deposit:
- This is a known complication of the use of adjustable valves. The valve has to be explanted.


Is it possible to test the patency of the shunt once the Sophy® or Polaris® valve has been implanted?

Yes, some conditions are required. Indeed, a ventricular catheter with a reservoir or a valve with an integrated reservoir is necessary to check the patency of the shunt.


Can the patient feel some noise from the Sophy® or Polaris® valve implanted on the skull?

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.


What is the incidence of MRI on the pressure settings of the Sophy® and Polaris® valves?

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 dysadjustment. The Polaris® adjustable pressure valve is the first adjustable pressure valve with no dysadjustment while exposed to a strong magnetic field such as 3 Tesla MRI.
The micro-magnets included in every adjustable pressure valves are responsible for the artefacts on the MRI 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 the site of implantation.
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.


Is it possible that the Sophy® and Polaris® valves be dislocated from their implantation site under MRI?

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."


Is there any heating effect from the Sophy® or Polaris® valve under MRI?

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


What is the relationship between operating pressure of the valve and intracranial pressure?

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.
A valve works in differential pressure. It will open only if the difference of pressure between the inlet connector and the outlet connector is higher than its operating pressure.
Indeed, 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, catheter length and diameter, intra-abdominal pressure in case of a ventriculo-peritoneal shunt). Thus there is little chance that the ICP will have the same value as the operating pressure of the valve.


What to recommend for a patient with a Sophy® SM8 or Polaris® SPV valve set at 110 mm H 2O who complains of headache when he is standing, which resolves when he lies down, and in whom a CT scan shows normal size ventricles?

The symptoms described are probably related to over-drainage.
The absence of slit ventricles on a CT scan could suggest that this is not the case, but in the presence of contradictory signs/symptoms, decisions should always be based on the clinical signs. The development of clinical signs often precedes the effects of over-drainage 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.


What to recommend for a patient with a Sophy® SM8 or Polaris® valve set to 70 mm H 2O in whom an early sub-dural haematoma has been diagnosed?

Development of a subdural haematoma in a patient with hydrocephalus fitted with 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 above, the valve is set at 70 mmH 2O. 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 hematoma, depending on the patient's condition.


What is the slit ventricle syndrome due to, in a patient fitted with a shunt with a valve? How would this be solved in a case in which the patient was carrying a Sophy® SM8 or Polaris® SPV set to 200 mm H 2O?

The slit ventricle syndrome is due to over-drainage. The major risk is the development of a subdural haematoma.
We would therefore increase the valve pressure.

In the case described, the valve is set to 200 mmH 2O, 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 mmH2O (SM8-400, SPV-400).


What precautions does a patient fitted with a Sophy® Mini Adjustable Valve have to take in his everyday life?

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 dysadjustment. 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 approached un-intentionally and also to direct shocks.


Is it possible to place the Sophy® or Polaris® valve between a ventricular catheter and an external drainage system?

Using an external drainage system with a valve should be avoided. In case of temporary externalization 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.


Are there any contra-indications in performing laparoscopic surgery on patients with Sophy® or Polaris® valve?

There are no contra-indications for laparoscopy on patients with Sophy® or Polaris® valves. Inflating CO 2 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.


How is it possible to trace the Sophy® and Polaris® valves?

All the Sophy® and Polaris® valves are manufactured with an individual serial number etched on the inferior face of the valve housing.
Moreover, each Sophy® and Polaris® valve is packaged with a Patient Identification Card (PIC) and a set of stick-on labels mentioning the reference number, Batch 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,…).


Can a Sophysa valve be re-sterilised?

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-sterilization.