strata_adjustable_pressure_valve [Neurochirurgie-Wiki] (2023)

OStrata®ValveofMedtronicis part of aventricular shuntsystem used to treat the symptoms ofhydrocephalus.

It's aAdjustable differential pressure valve.


The Strata valve has 5 settings or P/L, ranging from 0.5 to 2.5.

Each performance level corresponds to a range of opening pressures and flow rates; generally, a lower performance level corresponds to a lower opening pressure. The opening pressure range is between 15 and 170 mm H2O. Several models of the Strata valve were introduced, including the Strata II valve and the Strata small valve.

They all use the same radiographic scheme to assess the scenario; the position of a notched disk relative to 2 small dots defines the P/L configuration. Current product literature states that patients with Strata valves can obtain MR images using a static field of ≤3T, but inadvertent configuration changes are possible. He advises checking the settings after the RM image to ensure this has not occurred.1).

Strata Valve Pre- and Post-Operative Adjustment


stratum IIvalveit's aDetourcomponent designed to provide continuouscerebrospinal fluid flowofventricles of the brain in the right auricle of the heart or in the peritoneal cavity. The Strata II valve allows the clinician to non-invasively adjust the level of pressure/flow performance before and after implantation without the need for radiographic confirmation to meet the changing needs of the patient. In addition, the Strata II valve minimizes excessive reduction in intraventricular pressure and volume due to excessive CSF drainage, which can be caused bysiphon effectthe hydrostatic pressure of the distal catheter.

against indications

CSF should not be diverted into the peritoneal cavity or other areas of the body if there is infection in any area where the various components of the shunt system will be implanted. These include infections of the scalp and other skin areas through which the shunting system will pass, cerebral meninges and ventricles, peritoneum and intraperitoneal and retroperitoneal organs, pleura, and bloodstream. CSF shunting is contraindicated if there is infection in any area of ​​the body. In addition, shunting into the atria in patients with congenital heart disease or other severe cardiopulmonary anomalies is contraindicated.

Warnings and Cautions

magnetic fields

The Strata tubes were reprogrammed by direct contact (0mm clearance) with Bose headphones. When a rotation component was added, the 3 headset reprogrammed the Strata valves to 0mm. At all distances above 0 mm, the headphones did not affect the leads. The proGAV valve was not affected by headphones at any distance.

While all earphones studied generated significant gaussian fields at distances less than 5 mm, the programmable valve setting only changed at a distance of 0 mm (ie, with direct contact). Given the subcutaneous location of the valve, the authors conclude that it is highly unlikely that standard or commercially available headphones could contribute to lead reprogramming.2).

The pressure level setting of the valve should always be checked after exposing the patient to strong magnetic fields.

Devices known to contain magnets should be kept away from the valve implantation site, as they may affect the performance level setting of the Strata-type valve. All magnets have an exponentially decreasing effect on the valve the further away they are. Common ambient levels of electromagnetic (radio frequency) radiation generated by security scanners, metal detectors, microwave ovens, cell phones, power lines, and transformers should not affect the performance level setting.

Valve function and performance level setting should be verified if the valve is subjected to mechanical impact or major trauma.

Use Medtronic Neurosurgery PS Medical Tuning Kit REF 45805 to change the performance level of the Strata II valve.

The adjustment tool contains strong magnets. Care should be taken when using the tool near magnetically sensitive medical implants (eg pacemakers and vagus nerve stimulators), electronic equipment, data storage devices such as computer diskettes or credit cards.

The Locating Tool, Indicator Tool, and Adjustment Tool are NOT to be sterilized.

Ferromagnetic substances can impair the ability of tuning tools to change and confirm performance level settings.

See the fitting kit insert for instructions, warnings, precautions, and complications.

The appropriate product and size should be chosen for the specific needs of the patient, based on diagnostic tests and the experience of the physician. Product labeling specifies the applicable product performance levels or ranges.

Lint, fingerprints, baby powder, other surface contaminants, or residue from latex gloves can cause foreign bodies or allergic reactions.

Improper use of instruments to manipulate or implant shunt products can result in cuts, gouges, or crushing of components. Such damage can lead to loss of shunt integrity and require premature surgical revision of the shunt system.

Care must be taken to ensure that contaminants are not introduced to the shunt components during testing or handling prior to implantation. The introduction of contaminants can result in poor performance of the bypass system. Particles entering the shunt system can cause shunt occlusion or can also keep pressure/flow control mechanisms open, resulting in excessive drainage.

When connecting the catheters to the connectors, the surrounding ligatures should be secure, but not too tight, so that they do not cut into the silicone tubing.

Care must be taken when routing the catheters to avoid unnecessary kinks and abrasions along their route. Abrasion can result in premature catheter failure (fracture). The edge of the twist drill or reaming hole can be trimmed to provide a beveled notch where the ventricular catheter emerges and curves so that it is adjacent to the skull.

"Small" size catheters have thinner walls and lower overall resistance compared to "standard" size catheters. These features result in a comparatively higher potential failure (fracture) rate and therefore shorter life expectancy for "small" size catheters. Clinicians implanting "small" size catheters for cosmetic reasons must recognize the potentially higher rate of catheter revision and weigh this against the cosmetic benefit.

Patients with hydrocephalus shunt systems should be kept under close observation post-operatively for signs and symptoms suggestive of shunt malfunction. Clinical findings may indicate a shunt malfunction. Clinical findings may indicate shunt obstruction or excessive CSF drainage.

Shunt obstruction can occur in any of the components of the shunt system. The system can become clogged internally due to tissue fragments, blood clots, tumor cell aggregates, bacterial colonization, or other debris. Catheters that come into contact with internal body structures can become kinked or become locked at their ends (eg, placement of aventricular catheter tipin the choroid plexus or from the distal tip of the catheter to the greater omentum or intestinal loops). Finally, shunt obstruction can occur due to the growth of an infant or child, or physical activities that result in disconnection of shunt components or removal of a catheter distal from the intended drainage site.

Shunt obstruction can occur in any of the components of the shunt system. The ventricular catheter can become occluded by particles such as blood clots or brain debris, by inversion of the catheter tip in the choroid plexus, by embedding of the catheter in brain tissue, or by coaptation of the ventricular walls in the presence of drainage. excessive ("divided ventricle").

Disconnected bypass components can migrate further.

Bypass systems can fail due to mechanical malfunction, resulting in insufficient or excessive drainage.

Malfunction or obstruction of the shunt system can lead to signs and symptoms of increased intracranial pressure if the hydrocephalus is not compensated. In babies, common symptoms are increased tension in the anterior regionfuentes, congestion of the veins of the scalp, apathy, drowsiness and irritability, vomiting and neck stiffness. In older children and adults, common symptoms are headache, vomiting, blurred vision, stiff neck, impaired consciousness, and various abnormal neurological findings.

Excessive CSF drainage may predispose to the development of a subdural hematoma or hydroma or to collapse of the ventricular lateral walls leading to ventricular catheter obstruction.

If the ventricular catheter adheres to the choroid plexus or adjacent brain tissue due to fibrous tissue adhesions, it is suggested not to remove it forcibly. It is suggested that gently rotating the catheter may help free it. It is recommended to leave the catheter in place to avoid the risk of intraventricular hemorrhage, which can be caused by forced removal.

Subcutaneous catheter coils can break at welds or component mounting points or due to extreme deformation of the malleable rod. Sudden rupture can cause tissue or organ trauma and damage to the shunt system. Instruments must be inspected prior to use to ensure their continued integrity and functionality. Disposable instruments should never be reused as injury to the patient and physician may occur.

MRI InformationValvesThe Strata® II valve is considered MRI Conditional per ASTM F2503.

MRI systems up to 3.0 tesla can be used at any time after implantation and will not harm the Strata® II valve mechanism, but may alter performance level settings. Performance level settings should always be checked before and after MRI exposure.

Results of tests conducted to assess magnetic field, artifact, and heating interactions indicated that the presence of the tested valves should not pose a substantial risk to a patient undergoing an MRI procedure under the following conditions:

Static magnetic field of 3.0 Tesla or less

Spatial gradient of 720 G/cm or less

Radio frequency (RF) fields with an average Specific Absorption Rate (SAR) of 3 W/kg over 15 minutes. Exposure period of 15 minutes. The table provides maximum signal gaps (artifact sizes) for standard imaging pulse sequences at 3.0 Tesla per ASTM F2119.

Valve Pulse Sequence Plane Imagine Max. Vacuum signal (artifact), cm2 Stratum IIT1-SEParallel35.16T1-SEPerpendicular33.03GREParallel73.91GREPerpendicular66.55Adjustment KitsDO NOT take the adjustment tool to an MRI facility, as these magnets may present a safety hazard to the patient and/or or the user.

Proximity to the MRI array can impede the mechanism in the pointer tool due to the field strength of an MRI magnet. Leave the area before attempting to check a valve setting.


Complications associated with CSF ventriculoperitoneal shunt systems can be similar to those experienced with any surgical procedure performed under local and/or general anesthesia. These include reactions to drugs and anesthetic agents, electrolyte imbalance, and excessive blood loss, particularly in infants. On rare occasions, a patient may experience a reaction due to sensitivity to the implant.

In CSF shunt procedures, the most common complications are due to obstruction of the system, as described under “Warnings”. Obstruction can occur in any component of the system due to obstruction by brain fragments, blood clots, and/or tumor cell aggregates at some point along its path. Obstruction can also occur due to separation of system components or kinking and/or kinking of the catheter. This may predispose to migration of the ventricular catheter into the lateral ventricle and of the distal catheter into the peritoneum or other structure into which the catheter is implanted. As noted above, the growing infant or child may cause the distal catheter to be withdrawn from the atrium into the internal jugular vein or from the peritoneum into tissue planes where fluid cannot be absorbed.

There are other potentially serious complications. Local and systemic infections are not uncommon with bypass procedures. They are usually caused by organisms that inhabit the skin, mainly Staphylococcus epidermidis. Other pathogens circulating in the bloodstream can colonize the shunt and, in most patients, require its removal.

In 1973, Robertson et al. summarized the incidence of infection in ventriculoperitoneal shunts reported so far. Ventriculoperitoneal shunt infection occurred in 5–10% of patients in most reports.

In 1993, Kestle et al. reported significant reductions in infection (less than 4%) with the use of antibiotics, short surgery (surgical expertise), and control of the operating room environment (eg, designated operating room, limited staff and traffic, skin surfaces covers). The article states that results can also be obtained without the use of antibiotics, but with strict perioperative control of the environment.

The use of prophylactic antibiotics in shunted patients is somewhat controversial, as their use may predispose to infections by more resistant organisms. Therefore, the decision to use antibiotics prophylactically rests with the treating physician and/or surgeon. Diversion to the peritoneum may fail due to inversion of the catheter in the intestinal loops or in the greater omentum. Intestinal perforation by the peritoneal catheter with subsequent development of peritonitis has been described.

Excessive CSF drainage can cause excessive reduction in CSF pressure and predispose to the development of hematoma or subdural hygroma, and excessive reduction in ventricular size leading to obstruction due to impingement of the ventricular walls on the ventricular inlets. catheter. In the infant, this excessive reduction in pressure will cause marked depression of the anterior fontanelle, overlapping the skull bones, and may convert the communication into obstructive hydrocephalus.

The incidence of epilepsy after ventricular shunt procedures has been reported. This study also indicated that the incidence of seizures increased with multiple catheter revisions.

StrataVarius Fit System Indications

StrataVarius is designed to be used by clinicians to non-invasively identify Strata-type valve Performance Level (PL) setting and display this information numerically in terms of PL level and equivalent pressure reading in millimeters of water (mmH2O).

StrataVarius allows the user to non-invasively change the pressure setting of the valve without the need for radiographic confirmation.

against indications

The Medtronic Neurosurgery StrataVarius system is not intended to be used as a diagnostic tool, but only to confirm or change a pressure level in a Strata-type valve.

The StrataVarius should not be used on any fixed pressure valve. Use only on PS Medical Strata type adjustable valves. The StrataVarius is not intended for use in a sterile environment.

Warnings and Cautions

StrataVarius should only be used by qualified personnel, ensure users have adequate knowledge prior to use. An incorrect LP setting can cause excessive or insufficient CSF drainage, which can cause complications for the patient. Radiographic confirmation of pressure setting is recommended as an alternate method of determining Strata valve PL setting. Risks associated with radiographic imaging include exposure to low levels of radiation, radiation-induced damage to the skin and underlying tissues, or the possibility of developing radiation-induced cancer. Care must be taken to use the least amount of radiation exposure necessary to produce the image. Do not use the StrataVarius to detect or adjust any valve that is not a Strata PS Medical type. Check that the StrataVarius system is not damaged before use. Allow the StrataVarius to reach operating temperature before using it (see Operating/Storage Temperatures). Always be sure to verify that the correct smart card has been inserted. Use only StrataVarius specified 1.5 volt (AA) alkaline batteries. wear. A flashing battery icon indicates low battery (voltage); REPLACE BATTERIES. If the StrataVarius will not be used for 6 months or more, remove the batteries before storing. Batteries used in the StrataVarius can present a risk of fire or chemical burns if not treated properly. Do not disassemble, heat above 100 degrees C, or incinerate. Use of another type of battery may present a risk of fire or explosion. Dispose of batteries promptly and properly. Keep it away from children. Dispose of batteries or other StrataVarius system components in accordance with local environmental regulations. Do not touch the StrataVarius battery terminals. Do not use acetone as a cleaning agent, as it could damage the product. the Strata Varius system. Do not drop the StrataVarius or its components on hard surfaces, as this may cause internal damage to the device. To minimize the possibility of infection, clean the StrataVarius and Adjustment Tool between patients. The adjustment tool contains strong magnets and may damage credit cards. Keep away from all magnetic materials and cards, as well as computer hard drives and other magnetic data storage media. Strata Varius system. If the system needs repair, please contact your local Medtronic Neurologic Technologies sales representative or call Customer Service at 1-800-468-9710 for instructions. International customers should contact their local Medtronic Neurologic Technologies sales representative. StrataVarius provides a means to check the valve non-invasively; however, valve configuration can also be determined by X-ray imaging. This equipment has been tested and found to comply with the EN limits of International Standard EN/IEC 60601-1, ANSI/AAMI ES 60601-1, and CAN/ CSSA C22.2 No. 60601-1-08. These limits are designed to provide reasonable protection against interference in a typical medical environment. However, there is no guarantee that interference with other devices will not occur in any particular installation or use. If this equipment does cause interference with other devices, which can be determined by turning the instrument off and on, the user is encouraged to try to correct the interference by one or more of the following measures: Reorient or relocate the device Increase the separation between the equipment The StrataVarius system does not contain any latex material. WARNING: MODIFICATION OF THIS EQUIPMENT IS NOT ALLOWED.


A multicenter prospective randomized trial was conducted in a total of 58 patients with suspected NIPH. Thirty patients were assigned to group 1 (control) and received a Strata shunt (Medtronic, Goleta, USA) with the valve preset to a performance level (PL) of 1.0, while 28 patients were assigned to group 1. 2 and received a Strata bypass with the valve preset to PL 2.5. In this group, the PL was allowed to be reduced until there was improvement or radiological signs of overdrainage. RESULTS:

Significantly more subdural effusions were seen in patients who improved in group 1. There was no statistically significant difference in improvement between the two groups overall.

Based on this multicenter prospective randomized study, it is recommended that NIPH patients be treated with an adjustable valve shunt, preset at the highest and lowest opening pressure until clinical improvement or radiologic evidence of overdrainage occurs, although improvement is even slower and longer bypass settings may be the consequence3).

case series

In the study, we report the shunt experience of 24 patients with iNPH using the Strata® valve (Medtronic), following a protocol based on a positive Tap Test.

We observed clinical improvement in 20 patients and stability/worsening in 4 patients. Complications occurred in five patients, including one death. Results show improvement and complications occurred at a lower rate than reported in other studies.

The Strata® valve used in the proposed protocol represents an efficient and safe tool in the treatment of iNPH4).

Strata Adjustable Pressure Valve Alicante General University Hospital Cases

82 year old man withVentriculoperitoneal shunt placement3 years ago, he fell 3 weeks ago, hitting an iron board on the right side. Since then he has complained of continuous headache, which worsens in the afternoon. He is referring to the instability that he has increased since the coup.

CT artifact


Medtronic. MRI information. Consulted on May 22, 2009


Spader HS, Ratanaprasatporn L, Morrison JF, Grossberg JA, Cosgrove GR. Programmable Leads and Headphones: Are They Safe Together? J Pediatric Neurosurgery. 7:1-4 Jul 2015. [Epub ahead of print] PubMed PMID: 26149436.


Delwel EJ, de Jong DA, Dammers R, Kurt E, van den Brink W, Dirven CM. A randomized trial of high and low pressure level settings on an adjustable ventriculoperitoneal shunt valve for idiopathic normal pressure hydrocephalus: results from the Dutch Strata Shunt Study (DEPSS) from the Dutch screening program. J Neurol Neurosurg Psychiatry. 2013 Jul;84(7):813-7. doi: 10.1136/jnnp-2012-302935. epub2013 Feb 13. PubMed PMID: 23408069.


Oliveira MF, Saad F, Reis RC, Rotta JM, Pinto FC. The programmable valve represents an effective and safe tool in the treatment of patients with idiopathic normal pressure hydrocephalus. Neuropsychiatric Arc. April 2013; 71(4):229-36. PubMed PMID: 23588284.

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