A catheter assembly and related methods directed to stent delivery systems that include a stent and a catheter assembly having first and second balloons. The stent includes a side branch aperture and expandable structure defining the side branch aperture. The expandable structure is configured to move into a radial outward orientation relative to a sidewall of the stent. The portions of the first and second balloons are positioned within the stent in a generally coaxial arrangement with the first balloon extending distally from the distal open end of the stent and the second balloon extending proximally from the proximal open end of the stent. The expandable structure of the stent is moved towards the radial outward orientation by advancing the second balloon at least partially distally through the side branch aperture. In some arrangements, the second balloon is at least partially inflated when advanced through the side branch aperture.