Alan meets David Lederman, inventor of a promising new mechanical heart

It's been nearly two decades since the world watched Barney Clark struggle for 112 days with his artificial heart, the Jarvik 7. Clark's four-month ordeal, during which he was bound to a refrigerator-sized air pump and suffered four clot-induced stokes, cooled enthusiasm for artificial hearts.

But research on mechanical hearts has made giant leaps forward in recent years. In 1993, Michael Dorsey was one of the thousands of patients in desperate need of a heart transplant. As he awaited a donor, Michael's doctors at the Inova Hospital in Virginia fitted him with a Heartmate mechanical assist device. Attached to his left ventricle and aorta, the pump took over much of the work of his ailing heart. Unlike the Jarvik 7, the Heartmate's battery pack and portable air pump allowed Michael some degree of freedom. But like Clark, Michael had wires and tubes protruding from his belly, an uncomfortable and vulnerable condition.

The ABIOMED heart may one day save up to 45,000 Americans each year

Today, a new generation of mechanical devices is smaller and more efficient than ever. Alan visits a research lab where a fully implantable, permanent artificial heart is in the late stages of testing. Like a real human heart, the ABIOMED model has two pumping chambers and valves that regulate blood flow. This new device runs on a battery that can be recharged through the skin, so no tubes and wires need pass through the body wall.

The ABIOMED heart is already hard at work inside livestock, whose vital statistics the Massachusetts-based scientists monitor daily. Plans are underway for the first human trials to start soon -

For more on this topic, see the web feature:
"Searching for a Substitute"