Scientists have been making artificial human hearts for more than 30 years, but the U.S. Food and Drug Administration (FDA) has never given its full blessing to any of them. That may soon change. A panel of experts last week recommended that the FDA approve the CardioWest Total Artificial Heart for use as a temporary, fully implantable replacement heart that can keep a patient alive until a transplant can be found. That's lifesaving news for the 3,500 Americans waiting for a heart donor. But it's also a sobering reminder that only 2,000 human hearts become available through donation each year.