A thin-walled guide wire tube is fixedly and sealably attached to both a proximal section and a distal section of a balloon angioplasty catheter. A stent is co-axially mounted onto the inflatable balloon of the balloon angioplasty catheter. Because the guide wire tube forms an inner liner for the balloon angioplasty catheter, the fluid inflation lumen of the catheter is sealed so the inflation liquid that pressurizes the balloon will not leak as it would be if there were no “inner liner” and the balloon angioplasty catheter were attached to the guide wire itself. By not having a traditional inner shaft through which a conventional guide wire slides, the deflated balloon on which the stent is mounted can have a reduced diameter.