21.   Less advanced mechanical hearts are now used strictly as a bridge until transplant organs can be found, but these devices are hooked to external power sources and pumps.

22.   Less advanced mechanical hearts have been implanted in patients in the past, but they were all attached to outside electrical or pumping power consoles.

23.   Oxford Radcliffe Hospital said the operation was the start of a program of mechanical heart implants.

24.   Sensors command the mechanical heart to pump faster when the body is exercising and muscles need more oxygen, Kung said.

25.   The mechanical heart, called the AbioCor, is expected to enable patients to participate in normal activities, including light sports.

26.   These questions must be answered, he said, before a mechanical heart can assume an essential role in medicine.

27.   Unlike the earlier mechanical hearts, it has no wires and tubes that stick out of the chest and connect to a power source.

28.   Unlike the ill-fated mechanical heart, which entirely replaced the heart, these sit inside the chest and help the natural heart do its work.