Government scientists on Thursday narrowly rejected the first fully implantable artificial heart (search), saying they were unsure if a few extra months of life outweighed the serious side effects.

The AbioCor (search) artificial heart has been tested in only 14 patients. Two died immediately. The rest survived only about five months. Many patients had severe strokes that compromised their final days.

But one patient lived 17 months until the mechanical heart wore out. His family and one other told advisers to the Food and Drug Administration that the heart provided priceless extra time.

Yet the advisers wanted more testing to figure out just which dying patients should be offered a chance to try the heart.

While the panel deadlocked on whether to recommend sale of the device, it voted 7-6 that the probable benefit did not outweigh the risks.

"I voted against (this) with some angst," said Dr. Clyde Yancey of the University of Texas Southwestern Medical Center.

"The device has a clear level of promise," said Dr. Judah Weinberger of Columbia University.

Some panelists, after four separate votes failed to clear the device, urged the device's maker, Abiomed Inc. of Danvers, Mass., to study it more carefully.

The FDA is not bound by its advisers' recommendations, but usually follows them.

"This one, I think, is a real dilemma," said the FDA's chief reviewer, Dr. Julie Swain. She asked if, for most patients, the AbioCor was really "prolonging life, not prolonging death."

The AbioCor is a novel device, the first attempt at a mechanical heart that has no wire sticking through the skin. The battery that powers the softball-sized device is recharged by an electrical charge through the skin.

The heart is intended for patients who are dying from heart failure, who are not candidates for a transplant and who are not expected to live more than another month.

Only a very small subset of the 5 million heart-failure sufferers meet those criteria, and Abiomed had sought permission to sell under a "humanitarian device exemption."

That is a special program designed for devices that might help fewer than 4,000 people a year who have no other treatment options. The program requires only evidence of "probable benefit" without unreasonable risk.

Panelists wrestled all day with that question. They noted that more than half of AbioCor recipients had strokes and that some then lived their last weeks in a hospital and had little brain function.

One adviser, Dr. John Somberg of Rush University, said there is an "agonizingly thin" line between the possibility of benefit and harm.

Added Dr. Robert Nelson of the University of Pennsylvania: "Who should be the judge of that is an important question."

Abiomed said the strokes were caused by a design flaw that has been changed and by still unclear understanding of which patients were the best candidates and how much blood-thinning medication they needed.

Two families said that patients were helped.

The second recipient, Tom Christerson, 71, lived for 17 months, long enough to meet his first great-grandchild and spend another Thanksgiving with his family. The Central City, Ky., man was the only recipient able to move back home.

"Frankly, coming from this daddy's girl, each and every moment was priceless," said his daughter, Patti Pryor.

The first recipient was Robert Tools, 59, who lived with the heart for five months. "I wanted to tell you how important it was for him to have that implant," said his wife, Carol Tools. She recalled that he got to go fishing a last time.

But every family was not satisfied.

The advisory panel was not told that the widow of one recipient settled a lawsuit that claimed her husband was not adequately warned of what life with the mechanical heart would be like, and soon regretted taking part in the experiment.

Abiomed's chief scientific officer, Robert Kung, pledged that if it were authorized to sell the heart, the company would allow implants at only 10 hospitals where surgeons would get special training. He said the company also would continue studying how the next 20 patients fare.

If approved, the implant is expected to cost about $250,000. It is unclear if insurance would cover it.