A artificial ventricle comprises an inlet for receiving blood, an outlet for discharging blood, and a chamber disposed between the inlet and the outlet. There is also a mechanism for actuating the artificial ventricle between an expanded configuration and a contracted configuration. In the expanded configuration, blood flows into the inlet. In the contracted configuration, blood flows out of the outlet. There may be a one-way valve at the outlet for preventing blood flow back into the chamber. The one-way valve may be a diaphragm valve. The chamber may have a resilient outer wall. The chamber may have an ovoid shape.