John Holter was a machinist working for the Yale and Town Lock Company. His son Charles Case "Casey" Holter was born on November 7, 1955 with a severe form of spina bifida. Shortly after birth he contracted meningitis, which caused his head to expand rapidly. His parents were told that he had developed "water on the brain" or hydrocephalus.

As luck would have it Holter's son was being looked after in Philadelphia, where the surgeons Spitz and Nulsen had already demonstrated that a ventricle-to-atrium diversion system could work. What they needed was an expensive and impractical value that could controle the direction of the flow and maintain the cranial pressure.

A chance discovery showed Holter, after a failed attempt in which a young boy died, that he could use a silicone one-way valve (pressure sealing). After refinement of the silicone and rubber to a medcially suitable grade it was patented and manufactured as Silastic.

Dr. Spitz and John Holter set up a company to manufacture the shunts.

Although he was unable to save his son Casey, his design, the Spitz-Holter valve/shunt has helped millions around the world since the late 1950s.