partial VP shunt revision with programmable valve

I am 47 years old. I have Hydrocephalus and Syringomyelia from childhood, making me wheel chair bound now. A medium pressure VP shunt inserted 12 years ago failed to bring improvement. Cine MRI flow studies show partial block at 4th ventricular exit. Recent posterior fossa decompression surgery produced complications of ventilator associated pneumonia and aggravation of hydrocephalus. Neurosurgeon says there were thick arachnoid adhesions. I have been given the opinion of programmable shunt through which lower pressure settings can be achieved in stages. I am very afraid of another surgery given the devastating time of 3 months recovering from ventilator associated pneumonia.
A neurosurgeon told me that a programmable valve chamber (Medtronic Delta II valve) can replace the medium pressure valve WITHOUT revising the ventricular and peritoneal catheters. The origin/make of previous medium pressure shunt is not known. Its possibly not from medtronic company.
Can some body tell me if replacement of middle chamber only (the valve) is possible when the rest of shunt system is from a different company.