A circulatory assist apparatus comprises an inflatable pumping balloon having a proximal end joined to an elongated balloon catheter, the catheter having a distal end joined to the pumping balloon and a proximal end, separated from the distal end by a length sufficient to extend from within the circulatory lumen to the outside of a patient's body, for receiving positive and negative pressure pulses from a pump to inflate and deflate the pumping balloon; a proximal expandable frame comprising a distal portion of an elongated shaft surrounding the catheter; and a distal expandable frame. The distal end of the elongated shaft is abuttable against a stopping element surrounding the catheter as the shaft is advanced towards the inflatable pumping balloon, or is joined to the catheter in which case the proximal expandable frame is heat set to deploy spontaneously to a predetermined diameter upon release of the elongated shaft.