Abstract: A circulatory assist device, having an outer balloon and an inner balloon, with a control space between the outer and inner balloons. The device is mounted on a catheter, collapsed to a sufficiently small diameter to allow insertion into the vascular system of a patient. An expansion mechanism in the device, such as a stent, can be expanded to hold the outer balloon in an expanded state, while control fluid is pumped into and evacuated from the control space to repeatedly collapse and expand the inner balloon. At least one port is formed in the inner balloon, to allow vascular fluid to enter and exit the inner balloon as the inner balloon expands and contracts. After use, the expansion mechanism is contracted to a smaller diameter to allow withdrawal from the vascular system.

Abstract: A circulatory assist device, having a housing and a pumping membrane, with a control chamber and a pumping chamber. The device is mounted on a catheter, collapsed to a sufficiently small diameter to allow insertion into the vascular system of a patient. An expansion mechanism in the device, such as a stent, can be expanded to hold the housing in an expanded substantially rigid state, while control fluid is pumped into and evacuated from the control chamber to repeatedly deflect the pumping membrane. At least one opening is formed in the device, to allow vascular fluid to enter and exit the pumping chamber as the pumping membrane deflects. Introduction and evacuation of control fluid can be synchronized with the heart cycle of the patient. After use, the housing is contracted to a smaller diameter to allow withdrawal from the vascular system.