gms | German Medical Science

The German hydrocephalus study showed that three types of shunts are commonly used in Germany: simple differential pressure valves, adjustable shunts and gravity controlled devices. Although the results of the study could not demonstrate significant differences regarding the different principles, sophisticated implants are seen as the superior solutions. In respect to further improvement of shunts, the development of an adjustable gravitational valve seems to be the challenge of the present.

The new proGAV combines the advantages of gravitational devices with the possibility of „reprogramming". Two major requirements are important for adjustable valves: the unintended readjustment due to magnetic fields of daily life should be avoided and the adjusted pressure setting should be detectable without x-ray. The proGAV introduces a mechanical brake to ensure a safe pressure adjustment without the risk of unintended changes due to magnetic fields. Only if the brake is opened by an externally applied defined force on the device can the adjustment of the valve be performed. The adjustment as well as the reading of the adjustment can easily be done with a device, which looks like a pen. Both can easily be repeated within seconds. The adjustment of the valve has an impact on the vertical as well as on the horizontal opening pressure. The gravitational unit is integrated in the distal tube and uses the technology of the shunt assistant. The flat titanium housing of the proGAV is to be implanted retroauricularily. In contrast to all other adjustable devices the distance between the magnets integrated in the rotor is as large as possible to increase the reliability and safety of the readjustment. The valve uses 300 ° turning for the readjustment between 0 and 20 cm of water. A possible inaccurate measurement of 15 ° is equal to 1 cm of water. Hereby a precise adjustment is guaranteed.

The proGAV combines the benefits and drawbacks of adjustable and gravitational devices. The opening pressure of the valve is not affected by magnetic fields, the pressure setting can easily be detected without x-ray. The valve is designed to be implanted in children as well as in adults.

Clinical evaluation has to be performed to demonstrate whether or not the readjustment of gravitational devices might play an important role for the outcome of patients with hydrocephalus. Based on this experience, the need for an adjustable device only for the vertical compensation of the hydrostatic pressure of the standing patient should be considered.

The development was supported by the Land of Brandenburg