The Delta valve: How does its clinical performance compare with two other pressure differential valves without antisiphon control?

Objective: The Delta valve is a pressure differential valve with a siphon c ontrol device. The valve mechanism is normally closed, but is designed to o pen in response to positive ventricular pressure, thereby avoiding overdrai nage of cerebrospinal fluid (CSF). As a result, the incidence of subdural f luid collections as well as postural symptoms is purportedly reduced. in ad dition, the valve might reduce the number of obstructions as there would be no negative pressure sucking tissue and debris into the shunt system. In o rder to assess whether use of the Delta valve reduced the number of shunt-r elated problems as compared with two other pressure differential valves wit hout an antisiphon component, we performed a retrospective review of all ch ildren undergoing CSF diversion procedures at our institution. Methods: We reviewed the charts of 1,193 patients. Cases included 2,325 ventriculoperit oneal (V-P) shunt insertions or revisions from January 1, 1985, to December 31, 1994, per formed at our institution. The Delta valve and two pressure differential valves without antisiphon function were exclusively inserted d uring the following time periods: Holter-Hausner (H-H): January 1, 1985, to August, 1987; Heyer-Schulte (H-S): August, 1987, to June, 1991, and Delta: June, 1991, to December 31, 1994. Results: Of the cases reviewed, 475 pati ents underwent insertion of a VP shunt at the Childrens Hospital of Los Ang eles and had a total of 686 shunt operations. Median follow-up was 3 years and ranged up to 10 years. Kaplan-Meier analysis documented that 67% of H-H , 71% of H-S and 70% of the Delta valves were functioning at 1-year follow- up. At 2-year follow-up, 66% of H-H, 64% of H-S and 65% of the Delta valves were functioning. The difference was not statistically significant. The oc currence rate for symptomatic subdural fluid collections was 0.7% (1/130) f or H-H, 2.2% (3/139) for H-S and 1.0% (2/206) for the Delta valve (p = 0.52 ). The combined breakage/obstruction rate for the series was 7.7% (10/130) for H-H, 2.9% (4/139) for H-S and 4.9% (10/206) for the Delta valve (p = 0. 19). No Delta valves malfunctioned secondary to fibrous capsule affecting t he antisiphon device. Conclusions: in conclusion, it appears that performan ce of the Delta valve was not significantly different from the H-H and H-S valves, two valves without an antisiphon device. There was no significant d ifference in the occurrence of symptomatic subdural fluid collections based upon valve type, or in the combined valve breakage/obstruction rates based upon valve type. Copyright (C) 2000 S. Karger AG, Basel.