An implantable pump is configured to be implanted in series with blood flow from a heart. The pump includes a frame configured to be implanted within the natural blood flow of the heart such as a ventricular outflow tract an outlet valve of the heart, and a central axle configured to be affixed within the frame parallel to the blood flow. The pump also includes a rotor attached to the central axle and configured to rotate in order to pump blood, and at least two electromagnetic coils configured to be energized in order to cause the rotor to rotate.