A divided expert advisory panel concluded yesterday that the benefits of the first fully implantable artificial heart do not appear to justify the serious side effects.

The AbioCor artificial heart has been tested in only 14 patients. Two died immediately. The rest survived 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.

The panel deadlocked on whether to recommend sale of the device but voted 7 to 6 that the probable benefit did not outweigh the risks.

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

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

After four separate votes failed to recommend approval of the device, some panelists urged its 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, Julie Swain. She asked if, for most patients, the AbioCor was really "prolonging life, not prolonging death."

The AbioCor is 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 a small number of 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. Abiomed had sought permission to sell under a "humanitarian device exemption."

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

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

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 whether insurance would cover it.