Figure 4a : The Abiocor artificial heart. Surgeons implant the heart pump in the area from where the ventricles are removed. Channels that connect naturally to the ventricles are then sewn into artificial cuffs that snap on to the heart. Two independent hydraulic motors lie inside the heart. One motor maintains the pumping function to each ventricle while the other motor operates the motion of the four heart valves. Surgeons implant an electric coil in the abdomen area to allow for energy transfer across the skin. Patients wear a battery pack around the waist and must change the batteries several times daily. The system also includes an internal battery so that the patient may uncouple the external power source in order to take a shower [Abiomed, 2002]. One significant advantage to the Abiocor is the smooth surface of the blood sacs. Smooth plastics are important in order to ensure constant motion of blood cells. Any time blood stops moving along the surface of a material, potential for clotting develops. The smoothness of the plastic, called Angioflex, allows for minimal damage to the blood. Angioflex is also durable enough to withstand 100,000 beats a day for several years [Abiomed, 2002]. This plastic is a major contribution to the life and to the safety of the Abiocor. Figure 4b : Schematic representation of the Abiocor artificial heart, which has three subsystems. These subsystems include the heart pump, a computerized pump controller, and a power source. All of the subsystems cumulatively weigh around 4 pounds and operate so quietly that a “stethoscope is needed to listen to the heart sounds” [Abiomed, 2002].