Sorry Chuck, but if she's already on dialysis, no matter what kind, she's way past the Pre-anything stage. They don't put you on D unless you have ESRD - End Stage Renal Disease. I doubt the stents would cause any more blockage than what the original problem was that the stents attempted to fix. If the stents didn't work, the damage to the kidney would not be reparable with a new artery. Restored blood flow won't undo what's already happened to her kidney function.
You might want to check out
www.kidneyschool.org. It will explain pretty much everything about ESRD in basic terms. The more you know, the more sense you can make out of what the docs tell you - and figure out what questions to ask them.