a catheter system has a balloon angioplasty device disposed about a common lumen near its distal end . the balloon catheter is pre - fitted with a stent which is deployed when the balloon is inflated . the common lumen is in communication with multiple lumens within a proximal region of the catheter body to allow for positioning of the catheter over a movable guide wire and convenient delivery of imaging or interventional devices to a desired region of a body passageway being treated . the procedure for stent deployment optionally includes steps of imaging a lumen by ultrasound before and after stent deployment to identify the site at which a stent is needed , to confirm that the stent is being and has been deployed at a longitudinal position which does not overlap a branched segment of the body passageway , and to ensure that the stent has been radially opened to an optimum diameter .