structure either bonded to or embedded within a portion of the balloon wall or the entire balloon wall in one example construction plastic tubing can be extruded and blown into a balloon with a diameter similar to that of the desired central waist diameter preferably this balloon attains a molecular circumferential orientation and a diameter that is smaller than the diameter of an aortic annulus 12 the blown balloon is then placed into a bulbous mold and the end regions or bulb regions are heated or annealed to allow molecular rearrangement the central waist region can be cooled to ensure that the central waist will retain its circumferential molecular alignment upon further inflation of the balloon into the bulbous mold the bulb regions can regain molecular circumferential orientation to retain the large bulb diameter it is noted that this construction method can be also used to form a bulbous or hour glass shaped balloon out of a single polymeric material such that the waist will retain a smaller diameter and will not expand outwards to the diameter of the larger bulb diameters as the internal pressure is increased up to approximately 3 5 atmospheres the polymeric material can be for example pet nylon pebax or other nc or sc material that is suitable for forming such a.