An intravascular hemodynamic flow assist device (100, 500) comprising: a first shaft having a lumen, a proximal end, and a distal end; a second shaft having a proximal end and a distal end, wherein a portion of said proximal end of said second shaft is disposed within, and configured to telescope into and out of, a portion said lumen of said first shaft at the distal end of said first shaft; at least one set of pump blades (104, 504) adapted to expand to an expanded configuration from a first collapsed configuration and collapse from the expanded configuration back to said first collapsed configuration, wherein said at least one set of pump blades is attached to said first shaft and arranged such that said first shaft has the form of a helical screw pump; a motor attached to said proximal end of said first shaft for coaxially rotating said first shaft and said blades (104, 504) about said second shaft to pump blood through the device; a housing encircling and containing said motor; a cap attached to said distal end of said second shaft; and, a plurality of arms each having a proximal end and a distal end, wherein said proximal end of each of said plurality of arms is attached to said housing and wherein said distal end of each of said plurality of arms is attached to said cap; characterized in that the hemodynamic flow assist device further comprises a battery contained within said housing and configured to provide power to said motor, wherein said device is configured to be transformable between the first collapsed configuration and the expanded configuration, wherein the diameter of the first collapsed configuration is smaller than the diameter of the second expanded configuration, wherein said blades (104, 504) and said arms are configured to be compressed against said first shaft when the device is in the first collapsed configuration, and wherein said blades (104, 504) are configured to expand away from said first shaft and said arms are configured to expand away from said first shaft to form a cage surrounding said blades (104, 504) when the device is in said expanded configuration; and wherein said battery comprises a self-charging battery or inverter, wherein said self-charging battery is adapted to be chargeable by the unassisted flow of blood turning said blades when a patient having said device implanted is at rest. a first shaft having a lumen, a proximal end, and a distal end; a second shaft having a proximal end and a distal end, wherein a portion of said proximal end of said second shaft is disposed within, and configured to telescope into and out of, a portion said lumen of said first shaft at the distal end of said first shaft; at least one set of pump blades (104, 504) adapted to expand to an expanded configuration from a first collapsed configuration and collapse from the expanded configuration back to said first collapsed configuration, wherein said at least one set of pump blades is attached to said first shaft and arranged such that said first shaft has the form of a helical screw pump; a motor attached to said proximal end of said first shaft for coaxially rotating said first shaft and said blades (104, 504) about said second shaft to pump blood through the device; a housing encircling and containing said motor; a cap attached to said distal end of said second shaft; and, a plurality of arms each having a proximal end and a distal end, wherein said proximal end of each of said plurality of arms is attached to said housing and wherein said distal end of each of said plurality of arms is attached to said cap; characterized in that the hemodynamic flow assist device further comprises a battery contained within said housing and configured to provide power to said motor,