MADISON, WIS. -- A rare operation has left a man with two functioning human hearts and the chance of resuming a normal life, according to doctors at the University of Wisconsin Hospital.

In an eight-hour procedure last month, surgeons inserted a human donor heart into William Rammer, 53, to supplement his diseased heart, according to Barry Fields, the hospital's chief heart transplant surgeon.

"I can feel the difference . . . It seems like I have a stronger heartbeat," Rammer said at a news conference last week. "There's a twin heartbeat, and you can feel them overlap once in a while."

Rammer, a former vice president for a farm equipment manufacturer, said he was initially "a little bit apprehensive" when doctors discussed the procedure earlier this summer. "But it was either live with my old heart . . . or try this."

Rammer, who was discharged from the hospital last week, said he could barely breathe or eat and had to severely limit his activities before the operation. Now he plans to resume golfing and bowling.

In ordinary transplants, doctors remove a patient's failing heart and replace it with a donor heart.

But in Rammer's case, doctors opted for a "piggyback" transplant in which both a new heart and the ailing heart function in the patient's chest, Fields said. "It's a tight fit because we're not removing anything," the doctor said. "They're sort of kissing back to back."

Fields said the transplant, performed only 17 times in the world in the past year, is used only when patients over age 45 have high blood pressure in the lungs.

Such patients cannot withstand a necessary heart and lung transplant, so doctors then choose to insert a healthy donor heart to supplement the diseased heart, Fields said. If the patient's original heart stops functioning, it is not removed, and the patient can still manage with only the donor heart, he said.

The procedure was developed in the 1970s but had a low success rate, according to Fields, primarily because the body rejected the new heart. Anti-rejection drugs have made all types of transplants more successful, he said.

Rammer suffered from cardiomyopathy, a disease that destroys the heart muscle, as well as hypertension in his lungs. After the operation, his own heart pumped blood to his lungs while the new heart pumped blood to the rest of his body, doctors said.

Since then, the new heart has become stronger and is supplying blood to the lungs, a positive sign, Fields said. Rammer's original heart will continue to deteriorate because of the disease, but at a much slower rate.