Laboratory evaluation of the phoenix CRx diamond valve

OBJECTIVE: To assess the long-term hydrodynamic properties of a new cerebro spinal fluid flow-regulating hydrocephalus shunt called the CRx Diamond val ve (Phoenix Biomedical Corp., Valley Forge, PA). METHODS: Three samples of a Diamond valve were tested in the United Kingdom Shunt Evaluation Laboratory during a 40-day period. Tests were performed f or long-term pressure-flow performance, overdrainage, susceptibility to amb ient temperature changes, external pressure, reflux, presence of small part icles in the reagent, mechanical durability, and magnetic resonance imaging compatibility. RESULTS: Tests demonstrated that the Diamond valve stabilized flow within t he range of 0.36 to 0.62 ml/min when pressure varied from 14 to 23 mm Hg. H ydrodynamic resistance demonstrated pressure-dependent variability from 20 to 78 mm Hg/(ml/min). The time drift of hydrodynamic parameters was signifi cant (P < 0.001). The valve was insensitive to changes in temperature, exte rnal pressure, rapid fluctuations of differential pressure, small particles in fluid, and reflux. CONCLUSION: The Diamond valve demonstrated the intended variable resistance , which increased as the pressure increased. This property may help it limi t overdrainage related to body posture as well as nocturnal vasogenic waves . Flow through the valve stabilizes within a wide range, which may contribu te to the prevention of excessive pressure buildup after implantation. Howe ver, shunt placement should be avoided in patients who present with normal baseline intracranial pressure but an increased incidence of high vasogenic intracranial pressure waves.