Barney B. Clark, the rugged Seattle dentist who was the world's first recipient of a permanent artificial heart, proved that a mechanical heart can prolong life for 112 days, but public debate has just begun over whether it was worth it.

"It is a success in the area of science. There isn't any question it has moved the field forward," Dr. Peter Frommer, deputy director of the National Heart, Lung and Blood Institute said yesterday. From a technical standpoint, the the polyurethane-and-metal pump performed more smoothly and longer than most heart specialists had expected.

But from other perspectives--financial, ethical and the patient's quality of life--the degree of success remains uncertain. Most experts caution that the University of Utah artificial heart is still a research procedure that is far from ready to move into widespread use.

"The door that it has opened for other patients and for the public in terms of yet another quite elaborate, expensive form of treatment is a different issue. I would hope that the public will realize that we are still talking about something that can only be regarded as experimental and very limited in application. It would be a big mistake if people start queuing up for it now," warned Alexander M. Capron, executive director of the President's Commission for the Study of Ethical Problems in Medicine.

The heart institute, part of the National Institutes of Health, expects to appoint a new committee soon to grapple with the "societal, economic issues as well as the technological prospects," said Frommer. The government's research investment in artificial heart devices totals more than $10 million annually, but the strongest emphasis has been on devices that assist an ailing heart rather than replace it entirely.

The University of Utah team, which receives about $800,000 from the government each year, was one of the few pushing an air-driven device that currently requires the patient to be permanently attached by 6-foot tubes to a bulky external power machine that is plugged into an electrical outlet. Although the human implantation followed more than a decade of work with animals, critics such as Dr. David Banta of the congressional Office of Technology Assessment still believe it was "done prematurely."

But, despite initial skepticism, many others were impressed with the outcome.

"The result exceeded the initial expectations for what it might be possible to do," said Dr. John Watson, chief of the heart institute's devices and technology branch. "I think the scientific community is cautiously optimistic that there is good evidence that the system will work. Now it's a matter of completing the development," particularly of portable devices that will allow patients to live a more normal life.

"I think it was an important achievement . . . . But it's just a stepping stone along the way" to widespread use, said Dr. Antonio Gotto, president-elect of the American Heart Association and chairman of medicine at Houston's Baylor College of Medicine.

"Scientifically, we've established that the artificial heart works very well in humans," University of Utah Vice President Dr. Chase Peterson said in a telephone interview yesterday. Its only flaw was a broken valve that necessitated an emergency replacement two weeks after the initial surgery. He said a post-mortem had shown Clark's artificial heart to be in "perfect condition," without blood clots or infection.

The researchers have also accumulated data for the first time on how the cardiovascular system works in the absence of a human heart, said Peterson. It will take several weeks for the Utah scientists to analyze the case for submission to a university review board as well as the federal Food and Drug Administration, both of which will be done before proceeding on a second implant.

"Whether the quality of life was sufficient to justify the process" is for Clark's family and future recipients to decide, said Peterson.

Clark, 62, a retired dentist, chose to forestall impending death from end-stage heart disease, a decision that gained him nearly four months of life inside a hospital, tethered to a bulky machine. He tenaciously held on, despite numerous setbacks, several operations and a constant fight against infection that in the end appeared to overwhelm his already-deteriorated body.

But he and his family took pride in making a contribution to science, and he recently proclaimed "it has been worthwhile for me and would be for others in my situation because either they receive the heart or they die."

"He lived to realize that people were learning from what happened and his bravery was appreciated," said ethicist Capron.

But Arthur Caplan of the New York Hastings Center said that although Clark was well-informed from the beginning about what he faced, the roller-coaster path of his illness "raises questions about how far anyone should be willing to go in order to continue a medical experiment. We need to get better guidelines in place on when medical experiments should be stopped."

"Individuals should have the choice to accept or refuse it," added Dr. Robert Veatch of Georgetown University's Kennedy Institute. "But when we look at it in terms of resource allocation and other health care needs in our society . . . I think that our research priorities have to go to those who are in the greatest need for the basic essentials in health care."

Clark's operation and care cost $150,000 to $200,000, paid for by contributions to the university. Although the costs are likely to drop if the procedure becomes more widely available, its developers have estimated that demand eventually might exceed 50,000 people annually.

"We simply don't have the capacity to provide artificial hearts for everyone who would want one," Veatch concluded.