If I'm following what your speaking of, the best way to think of the system of blood vessels that 'feed' into the kidneys is a larger tube that divides into a large mass of smaller and smaller tubes that form a kind of a 'ball-like' structure. This 'ball' (there are probably millions of them) is surrounded by a type of 'cup' and the pressure of the blood inside the balls forces the fluid through a series of 'mesh-like' structures into the cup(s) where it flows through the rest of the system.
If, anywhere through this whole system, the pressure is too high - whether it's in the larger pipe that feeds the smaller pipes/or if it's in the smaller pipes - the high pressure can 'balloon' the pipes and if the pressure is too high it can be very dangerous. What happens overall is the structures won't be able to perform their proper functions. High pressures can poke 'holes' in the tubes and you can lose vital components from the blood into the kidneys; things can get 'clogged up' so that filtration can't be done, etc.
Thanks for the info. I will have to see if this applies to my wife's issues.
Thanks again.