Bypass surgery limitations are based on a number of factors. First off, you only have so many arteries/veins that the surgeon can harvest and use. Once used, that's it. If stents are in an artery which have blocked, then there is no way to graft onto that area. If a bypass fails early (mine lasted 3 months) then you are considered intolerant of bypass.
If you are suffering such severe pain a year after surgery, then something obviously isn't right and investigation is required. It could be that one of the sternum wires inserted to hold your sternum together while it mends has snapped. It could be many things and tests are required. There is no need to suffer the pain, they should be able to determine the cause.
I had quad by pass on January 1st 2013 , i am now getting server upper leg pain . I have been doctors and hospital and i have concluded that there is no answer and thats how it is . Can any one help because it reducing me to tears with the pain even