The efficient use of space and energy is achieved in a new implantable total artificial heart (TAH). To fit the orthotopic thoracic space, toroidal blood pumps encircle an energy converter, consisting of a centrifugal hydraulic fluid pump and a rotary reversing valve. The new centrifugal pump produces cardiac outputs of 6 L/min, with an average hydraulic efficiency of 47%. Toroidal blood pumps encircling the pump deliver a 60 cc stroke with an 85% ejection fraction and have a predictable blood flow pattern with no stagnant regions. Components have been characterized in vitro, and blood contacting elements have been tested in vivo.