A balloon catheter assembly (10) includes a balloon structure (20) formed of an inner balloon (40) and an outer balloon (70) which entirely envelops the inner balloon (40). The inner balloon (40) can be filled with air or other echogenic fluid and inflates to a diameter substantially less than the inflated diameter of the outer balloon (70), typically to a diameter of no more than 50% of the inflated diameter of the outer balloon (70). The inner balloon (40) can be inflated with air or other echogenic fluid, enabling the balloon structure (20) to be visible under ultrasonic imaging. The inner balloon (40) is protected within the outer balloon (70) and is shorter than the outer balloon (70). The assembly (10) can be used for PTA procedures, for deploying an implantable medical device or for other medical applications.
