Fig. 1.

The outer appearance and cut surface of the popular shunt valves. A: Gravity assisted valve. a: Ball-in-cone valve, b: Gravity valve (SA: shunt assistant), c: Tantalum ball B: Sophysa Polaris valve (SPV). Arrow indicates the type of SPV. The right side dots indicate the pressure setting (1: lowest, and 5: highest). C: Codman Hakim Programmable Valve with Siphon Guard (CHPV-SG). a: Leaf spring, b: Ruby ball and Ruby seat, c: CAM, d: Second pathway, e: Main pathway D: Strata II valve. a: Delta chamber, b: Distal occluder, c: Valve mechanism, d: Reservoir, e: Proximal occluder.