A wedge wire for maintaining the patency of an opening to a branch vessel while installing a stent in a main branch of a narrowed bifurcated vessel is provided. The wedge wire has a wedge portion that is larger than the rest of the body of the wedge wire and this wedge portion is used to maintain patency of the branch vessel when a balloon catheter is used to expand a stent in the main branch across the opening of the second branch.