According to Technology Review:
Earlier this month, the first fully implantable artificial heart was approved by the Food and Drug Administration. It brings hope to patients who are near death from heart failure; yet some major problems remain with it--namely, its large size and relatively short lifespan.
The current artificial hearts and circulatory assist devices mimic the heart beat with a pump, but a variation on this new artificial heart is a continuous flow device:
But an alternative design, conceived by O.H. "Bud" Frazier, a prominent heart surgeon and pioneer in the development of cardiac devices at the Texas Heart Institute in Houston, pumps blood through the body continuously, rather than with the periodic beat of the normal heart.