An angioplasty device for dilating the lumen of a human blood vessel has a balloon and a tubular guide wire bonded to one end of the balloon. The guide wire is in fluid communication with the balloon. A guide extension is bonded to the opposite end of the balloon from the guide wire. An elongated spring member is positioned within the balloon, and is bonded at one end of the spring to the guide wire and at the opposite end of the spring to the guide extension to interconnect the wire and the extension. The spring member is attached between the wire and the extension in compression to urge the balloon into a collapsed configuration when the balloon is not inflated with fluid. The guide wire is strengthened by bonding a helical structural member to the outer wall of the guide wire.
