I actually have the same question. I had my shunt put in in 1982 then it was replaced about 6 months later when it blocked.
I have had no other trouble, however I use to suffer form miagrane headaches which were at first misdiagnosed as a problem with my shunt as the symptoms are very similar, ie horrible headaches and projectile vomitting.
I was planning on heading to South America and doing the Inca trail on my way back to australia, but dont know anything about altitude and my shunt. I have travelled quite a lot in the past but never that high up