Pump (1) has bearings (11, 12) respectively arranged in fixed and removable walls (5, 10) of a pumping chamber, where the wall (10) is fixed on a case to close the chamber. An outer gear (13) has an end flange (14) that is removable so as to be separated from an end flange (15). The case has a housing (2M) for an electric motor (3) and separated from the chamber by the fixed wall. The motor has a hollow shaft (8) rotatably driving an inner gear (9) traversing the fixed wall, where the shaft is traversed with a clearance by a tie rod (22) fixing the removable wall to the case. An independent claim is also included for an artificial heart comprising artificial left and right ventricles with a closing cover arranged on a body.
