The HeartMate II pump is implanted below the heart with its entrance attached to the left ventricle and its exit connected to the aorta (the main blood vessel carrying blood from the heart to the body). Blood flows from the heart into the pump. A small electric motor in the pump drives a rotor (similar to a propeller) inside the pump that pushes the blood into the aorta and out to the body. A flexible tube passes through the patient’s skin and connects the implanted pump to a small controller worn outside the body. The controller is powered either by batteries or connected by means of a power supply to a standard household electrical power outlet.