A cardiocirculatory aiding device is disclosed generally comprising a housing with a cavity, an inlet, an outlet, and first and second sides with apertures therein, first and second shells mounted to the sides of the housing, and first and second membranes disposed between the housing and the shells such that the membranes cover the apertures in the sides of the housing, thereby creating a central blood chamber and two outer gas chambers. A pump supplies gas through a duct into the gas chambers to cause the membranes to flex into the blood chamber to pump the blood in that chamber through the outlet. In some embodiments, the pump is external and the duct passes through an incision in the body. In some embodiments, the membranes are elastomer membranes.