A heart assist device (10) adapted for implantation into a patient (99). The device (10) includes an aortic compression means (60) adapted, when actuated, to compress an aorta (15) of a patient (99), a fluid reservoir (74) and a pump means (71) adapted to pump a fluid from the fluid reservoir (74) to the aortic compression means (60) so as to actuate the aortic compression means (60) at least partly in counterpulsation with the patient's heart. The fluid reservoir (74) is adapted to be wholly positioned within the chest cavity of the patient (99).
