for threading the catheter the catheter could of course have a channel formed in it for the placement of a guide wire on which the catheter could travel the external wall 34 of the catheter has a plurality of passages 36 therein for the passage of pressure fluid into the interior of the balloon 40 the balloon 40 consists of a skin 42 which is connected to the wall of the catheter at a tapered or arcuate front portion 44 and a tapered or arcuate rear section 48 as seen from fig2 the balloon can be attached to the catheter wall by any convenient bonding method known in the art for example at the front section of the balloon 42 the balloon is tapered to a cylindrical section approximating the size of the catheter wall and is bonded to the wall by means of a bonding agent the rear portion 48 of the balloon shows another method for attaching the balloon to the wall of the wall of the catheter in which the end of the balloon is folded over so as to be inside the expandable chamber as mentioned various adhesives or other bonding agents or ultrasonic welding can be used as well as any other wellknown bonding means for attaching the balloon to the catheter section the middle portion 46 of the balloon is cylindrical in shape and of relatively uniform and continuous surface this is the portion of the device which is intended to press upon the stenotic structure to dilate the same by expansion of the balloon as seen in fig2 and 3 embedded in the.