The first self-contained, mechanical heart was implanted Monday in an ill American patient on the brink of death.

The titanium and plastic pump was inserted by University of Louisville surgeons during a landmark experimental operation at Jewish Hospital in Louisville, Ky. The implant is expected to extend the patient's life only a month or so.

Drs. Laman Gray and Robert Dowling, who trained by implanting the grapefruit-sized device in calves, performed Monday's surgery. No personal information on the patient was given, not even whether it was a man or a woman.

"The patient is resting comfortably," the hospital said in a statement Tuesday.

The device, known as AbioCor, is designed to allow recipients to maintain a productive lifestyle while wearing it. It is considered a technological leap from earlier mechanical hearts.

It features an electric-powered pump designed to fit inside the chest with no wires or tubes sticking through the skin. Power is sent from a battery pack worn outside the body through the skin to an implanted coil, control package and backup battery.

Experts hope AbioCor, made by Abiomed Inc. of Danvers, Mass., will lead to new hope for patients with failing hearts.

Heart surgery teams at five hospitals had been trained and poised to remove a diseased natural heart and install AbioCor in its place.

David M. Lederman, Abiomed's president and chief executive officer, said earlier this year the company had received Food and Drug Administration approval to perform at least five human trials with the artificial heart. If the experiments are successful, more patients could be added to the trial later, he said.

The patients selected for the trial must be suffering from a chronic, progressive heart disease expected to result in death within 30 days. They had to be ineligible for receiving a human heart transplant.

The goal of the experimental trials with the artificial heart is to "double the life span of these patients" to 60 days, Lederman said.

"Every patient will probably die on the AbioCor," he said. "We need to understand that, with this new technology, we may have failures."

Lederman said a second goal is to evaluate how the mobile mechanical heart affects the quality of life of those patients, most of whom are so ill that they cannot walk or perform the daily routine of life, such as getting dressed.

Artificial hearts used experimentally in the 1980s were different in that they were attached by wires and tubes to machinery outside the body.

The first recipient, Barney Clark, a Seattle-area dentist, lived 112 days after receiving a Jarvik-7 device on Dec. 2, 1982. The survival record for a total artificial heart is held by William Schroeder of Jasper, Ind., who lived 620 days on one before he died in August 1986.

But artificial heart patients of the 1980s all had a variety of complications, and use of the devices as permanent replacements for diseased hearts was largely suspended.

Still, the scientists building the next generation of devices — including those that assist rather than replace a diseased heart — learned too much to consider those early tests mistakes.

The second man to receive a Jarvik-7, Thomas Gaidosh, of Sutersville, Pa., was on the device only a few days before he received a human heart transplant. He lived 11 more years, long enough to be best man at the wedding of inventor Dr. Robert Jarvik.

Five hospitals had been approved as sites for implanting the AbioCor. The company had said it was not known which one would wind up being first. The others are Brigham & Women's and Massachusetts General in Boston; Hahnemann University Hospital in Philadelphia; the Texas Heart Institute in Houston; and the UCLA Medical Center in Los Angeles.

The Associated Press contributed to this report.