A balloon elongation apparatus includes an elongated hypotube with a distal end having a reduced inner diameter portion that is configured to radially expand when a mandrel is advanced through a lumen of the hypotube towards the reduced inner diameter portion. A medical kit includes a catheter having a distally-located balloon and the elongation apparatus disposed within a guide wire tube of the catheter. In use, the balloon is elongated following a procedure in order to facilitate retracting the balloon into a sheath. The balloon is elongated by first advancing the mandrel relative to the hypotube so that the hypotube radially expands and firmly engages an inner surface of the guide wire tube and then advancing the mandrel, hypotube, and distal end of the guide wire tube relative to the catheter body.