A circulatory assist apparatus comprising: an inflatable pumping balloon (1.1) having a proximal end joined to an elongated balloon catheter (1.20), the balloon 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 (1.3) comprising a distal portion (1.77) of an elongated shaft (1.2) surrounding the elongated balloon catheter, wherein the distal end of the elongated shaft is either abuttable against a stopping element (1.86) surrounding the elongated balloon catheter as the shaft is advanced towards the inflatable pumping balloon or joined to the elongated balloon catheter, such that longitudinal sliding of the elongated shaft relative to the elongated balloon catheter is transformed into radial expansion of the proximal expandable frame; a distal expandable frame (1.3) surrounding a segment (1.24) extending from a distal end of the inflatable pumping balloon, wherein a proximal end of the distal expandable frame is joined to the segment or a balloon tip (1.23) of the inflatable pumping balloon and a distal end of the distal expandable frame is reversibly slidable along the axis of the segment, and wherein a linearly movable operating member (1.18) either includes an end cap (1.17) operatively couplable with a distal end of the distal expandable frame or is joined to the distal end of the distal expandable frame, such that linear movement of the operating member relative to the segment is transformed into radial expansion of the distal expandable frame. an inflatable pumping balloon (1.1) having a proximal end joined to an elongated balloon catheter (1.20), the balloon 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 (1.3) comprising a distal portion (1.77) of an elongated shaft (1.2) surrounding the elongated balloon catheter, wherein the distal end of the elongated shaft is either abuttable against a stopping element (1.86) surrounding the elongated balloon catheter as the shaft is advanced towards the inflatable pumping balloon or joined to the elongated balloon catheter, such that longitudinal sliding of the elongated shaft relative to the elongated balloon catheter is transformed into radial expansion of the proximal expandable frame; a distal expandable frame (1.3) surrounding a segment (1.24) extending from a distal end of the inflatable pumping balloon, wherein a proximal end of the distal expandable frame is joined to the segment or a balloon tip (1.23) of the inflatable pumping balloon and a distal end of the distal expandable frame is reversibly slidable along the axis of the segment, and wherein a linearly movable operating member (1.18) either includes an end cap (1.17) operatively couplable with a distal end of the distal expandable frame or is joined to the distal end of the distal expandable frame, such that linear movement of the operating member relative to the segment is transformed into radial expansion of the distal expandable frame.