Medical device manufacturer, Medtronic, has issued a medical device safety alert concerning its Strata II, Delta, and CSF-Flow Control Valves and Shunts.

According to the manufacturer, there is a potential for variation in radiopaque marking visibility under radiographic imaging for Medtronic adjustable and fixed-pressure valves that are used in the management of hydrocephalus. The manufacturer is working to reduce variation and ensure radiographic visibility of the radiopaque markings. This issue does not impact the therapeutic pressure performance of these devices, however variation in radiopaque marking visibility post-implant may limit the ability to determine pressure settings and flow direction with radiographic imaging. Alternative methods for determining pressure settings and flow direction are described below.

After implanting Medtronic adjustable or fixed-pressure valves for management of hydrocephalus, there may be situations where it is desirable to determine or confirm pressure settings and flow direction. One method for this determination is to utilise radiographic imaging. Medtronic valves contain radiopaque tantalum-impregnated markings that can be viewed under plain radiographic imaging to determine the pressure level and/or current pressure setting of the valve and direction of flow.

If the physician is unable to visualize the radiopaque markers, the physician may use other methods (e.g. StrataVarius or Indicator/Locator tool, physical assessment) to obtain the necessary information, or the physician may consider utilizing additional radiographic imaging with contrast to determine the direction of flow.

Affected users should consider the following information when pressure setting or flow direction markings are not visible under radiographic imaging.

Determining/Confirming Pressure Settings:

• Strata Valves: Medtronic Neurosurgery Strata II valves provide a non-invasive method to address changing patient needs in the management of hydrocephalus. The unique valve design allows the physician to adjust valve pressure or performance level by using the Medtronic Neurosurgery Strata II Adjustment Kit or the StrataVarius Adjustment System.
• Delta and CSF-Flow Control Valves: All valves and shunts are accompanied by Patient cards/Wallet cards that are provided to patients to maintain in their records. Affected users should refer to these cards as they may provide the surgeon with information regarding pressure level/current pressure setting of the valve, valve type, and manufacturer.

Determining/Confirming Flow Direction:

• Placement that results in incorrect flow direction can present with clinical symptoms within a few hours post-implant of the valve. However, in the unlikely event flow direction is uncertain, radiographic imaging with contrast may be considered, if necessary, for determining flow direction. This imaging procedure may have inherent risks as well, and the decision to proceed is at the physician's clinical discretion.
  • Strata Valves: Ventricular and peritoneal catheters used with shunts are radiopaque and may help determine the direction of flow of Strata valves based on the overall orientation of the valve in relationship to the catheters (Radiopaque valve rotor must be towards the peritoneal catheter; valve dome must be towards ventricular catheter). If necessary, radiographic imaging with contrast may be performed to determine flow direction of a valve.
  • Delta and CSF-Flow Control Valves: If necessary, radiographic imaging with contrast may be performed to determine flow direction of a valve.

As of 22 Dec 2020, the manufacturer has received 9 reports regarding inadequate visualization of the radiopaque markers under radiographic imaging. No reports of patient harm have been associated with this issue. Inadequate visualization of the radiopaque markers should not significantly hinder the physician's ability to manage a patient with an affected product, nor would this impact treatment decisions for symptomatic patients.

According to the local supplier, the affected products are distributed in Hong Kong.

If you are in possession of the products, please contact your supplier for necessary action.

Posted on 19 January 2021