Abstract: A totally implantable artificial heart with two ventricles is disclosed. The blood is pumped alternately from each ventricle using a linear electric motor that moves an armature to push the movable walls of the ventricles. The motor may be made small, and hence light, if it is electrically inefficient. Excess heat is transferred by the convective motion of a heat transfer fluid through special passages in the motor and by effective conduction paths designed into the elements. The motion of the heat transfer fluid is engendered by the movable walls that at the same time are performing the pumping action.