Disclosed herein are proximally-flaring stents and balloon catheter systems and methods for using the same to restore patency to a side branch and its ostium at a vessel bifurcation, where the side branch can only be approached from the direction of the main artery. The system and methods include a proximally-flaring stent (10) and one or more balloon catheters (250, 400) with inflatable balloons that are able to push a flanged proximal portion (40) of the proximally-flaring stent entirely against the artery walls of the main artery of the side branch so that blood flow is not occluded.
