The operating room was ready, a medical-administrative team of dozens had gathered, a press room was about to be set up downstairs. The world's first implantation of a permanent artificial heart could begin, just as soon as Barney B. Clark, the patient at the center of the drama, signed the consent form.

Breathing with difficulty, his heart dangerously soft and weak from disease, Clark read the last, doom-laden sentence, informing him of his right to withdraw from an operation that had absolutely no guarantees. His small audience was stunned as he managed a wry smile.

"There sure would be a lot of long faces around here if I backed out now," he said.

It was one last bit of pointed humor from a man who had always wanted to stay in control of his life, but was now forced by his failing heart to offer himself up to history. Clark once more had demonstrated the qualities that had led doctors to choose him for the operation in the first place: a good grip on reality and a sense of humor and of self that could carry him through any crises ahead.

"He was a natural," said Peg Miller, the implant project social worker assigned to Clark and his family. "He had an extremely strong will to live. He had everything to live for and nothing not to live for."

Now, having survived three weeks on the artificial heart and starting to talk and walk again despite two follow-up operations and a major seizure, Clark, 61, a retired dentist from the Seattle suburb of Des Moines, has become a world phenomenon.

"We thought he was going to die," said A.E. Rothermich, the University of Utah official who worked months to set up a network of personal contacts and goal-oriented activities that would prepare the project team for both success and failure.

But Clark was the key, and the story of what brought him to the center of world attention here illustrates how useful very old values are on the frontiers of the most modern and sophisticated medical science.

The doctors involved in the project, artificial heart project leader Dr. Willem J. Kolff, surgeon Dr. William C. DeVries and Dr. Chase Peterson, University of Utah vice president for health sciences, wanted a patient with a proven ability to handle personal crises.

Clark's record on that score went back to age 12, when his father died and Clark had to work to help his mother keep up payments on their house in Provo, Utah.

According to Miller, the young Clark sold hot dogs at Brigham Young University athletic events, mowed lawns, baby sat, worked in a grocery store and peddled vegetables he bought from farmers outside town. He continued to work his way through BYU, then joined the Army Air Corps in World War II and helped train bombardiers.

He married Una Loy, also from Utah, during the war. Their marriage, which produced three children, was one more bit of solidity that impressed the heart project doctors, for Clark was going to need a great deal of emotional support after the operation. Peterson has described the Clarks as "two rugged old Rocky Mountain sagebrushes."

In their early years after the war, Mrs. Clark worked as a secretary and typed term papers on the side so that her husband could complete work at the University of Washington's dental school.

They wanted to return to Utah after that--their long ties with the state and their many friends there also influenced the heart project doctors--but Clark found an opportunity for a practice in the Seattle area too good to pass up.

The practice became very large, and Clark was "a slave" to it, said his friend and frequent golfing partner, insurance executive Pete Campbell.

Clark developed some health problems in 1977, and decided to cut down on his work load, but he had become so personally committed to his patients that he could not bear to turn away some and not others. In the end, he decided it best to retire from the practice altogether, devoting his time to some financial consulting and golf.

At some point shortly before or after his retirement, Clark apparently contracted a viral infection that three years ago turned into cardiomyopathy, a severe weakening of the heart muscles suffered by an estimated 5,000 to 20,000 Americans, Peterson said.

Dr. Jeffrey Anderson, the Salt Lake City cardiologist Clark sought out for special drug treatments, said the initial virus has never been identified, but all the standard and some experimental drugs failed to reverse the condition.

After his retirement, Clark haunted the Rainier Golf and Country Club, a short but treacherous 72-par golf course he played at least four times a week. He served as club president two straight years.

Before his illness turned his body puffy, he was a tall, rangy figure on the course, holding a 6 to 9 handicap, excellent for a man his age, slamming long drives and working with club professional Ray Bennett on his erratic short iron shots.

When the sickness reached the point two years ago when he was too tired to play, Clark still could not stay away. Bennett said Clark would come out to the course, get in a golf cart and just ride around, looking at the first, willows and alders decorating the pretty little course, and stopping to chat with his friends.

He finally became so ill, Bennett said, that he asked that his membership be withdrawn so someone else could use it, but the club board instead voted him a lifetime membership.

One of the drugs Clark was taking might work for a while, and he would feel fit enough to be driven to see one of his favorite football teams, the Seattle Seahawks and the University of Washington Huskies. If the car could park close to the stadium gate and an elevator was available, he could make it, but often even that was too much.

With no other option left, Anderson suggested three months ago that Clark meet DeVries. The potential of the artificial heart experiment intrigued Clark.

"I found him quite perceptive," said Anderson, who said the university doctors were also impressed by Clark's medical background -- one of Clark's sons was also a surgeon -- and his ability to appreciate the seriousness and potential problems in the experiment.

Clark toured the artificial heart research laboratory, housed in an old, five-story brick hospital building in northwest Salt Lake City. An experimental heart had just been implanted in a calf, one of 250 animal implantations performed so far by the laboratory staff.

Director Dan B. Olsen, an innovative veterinarian, showed Clark the animal with the two long air hoses to power the heart emerging from its chest and attached to an air compressor, the same lifetime tethers the first human recipient would have to wear.

Olsen also discussed with Clark and his wife the problems they had encountered. Olsen had begun working with Kolff, the doctor who invented the kidney dialysis machine, in 1967, and joined the laboratory in 1972.

The staff was working with an artificial heart designed by Dr. Clifford Kwan-Gett, but it was so large it pinched off veins bringing blood to the heart, and so a switch was made to a different design by Dr. Robert Jarvik. Olsen showed the medical doctors that splitting open breastbones, as they routinely did in human heart operations, was too much of a strain on calves.

He developed a way to implant the hearts from the side of the chest, taking out a rib, and ordered a switch to use of polyurethane plastic instead of silicon rubber in the artificial devices.

Three-month-old calves seemed the best animals with which to experiment. A human-sized heart would be too small for a full-grown cow and too large for most apes.

But calves eventually would outgrow the heart, so the laboratory doctors experimented with artificial hearts in full-grown sheep, taking special precautions during the operation because of unusual sensitivity of sheep blood to the heart-lung machine that kept the anesthetized animal alive.

By late 1981, Olsen said, the laboratory had set a record, keeping a calf named Lord Tennyson alive for 268 days with a Jarvik-5 heart before it finally succumbed to a mysterious infection, already weakened by the heart's inability to pump enough blood for its growing body.

Olsen said infection remains the most prevalent killer of his lab animals, but noted that he did not have the funds to keep his animal lab, a converted hospital laundry, as clean as most human environments and that most of the infections could be arrested easily in humans.

In some cases mineral deposits have formed on the artificial heart or valves have broken, as has already happened in Clark's case, but the lab has developed cures for both.

During his tour of the lab, Clark also saw a sheep named Teddy, who by the beginning of the new year will have survived seven months with an artificial heart and will be closing in on Lord Tennyson's record. Another sheep, Lodestar, has gone two months.

The project's other four surviving animals, Jungi, Magic, Theseus and Hercules, are all calves and have had their plastic and aluminum hearts from two to 3 1/2 months.

Clark seemed very observant to Olsen, an impression reinforced when Clark recognized Olsen, dressed in surgical garb, shortly after he recovered from surgery.

When Clark returned to Salt Lake City in early December, so close to death that he had to be taken from the airport to the hospital by helicopter, the institutional review board set up to clear patients for the artificial heart was equally taken with the Seattle dentist.

"He had a sense of humor, even in the midst of all that," said Ross Woolley, a public health professor who is vice chairman of the board. "He was not dispassionate or unmoved . . . , but he was intelligent, he knew what was coming."

The U.S. Food and Drug Administration had cleared the university medical center to perform the operation on patients who were too weak after heart operations to come off the emergency heart-lung machine.

When no such patients appeared, the FDA added "Class IV" patients, whose hearts were so weak they were uncomfortable even when lying in bed. By Dec. 2, the day of the operation, Clark fit that category, and so DeVries installed the new Jarvik-7 heart.

Three weeks later, with Clark taking a few steps on his own and preparing to meet the media, doctors still warn of unexpected setbacks.

"We are walking uncharted ground," Peterson has said several times. But the team organized to see the experiment through has begun to help the Clarks find a home in the Salt Lake City area where they could live within a 45-minute drive of the medical center in case of emergencies.

Like most of the residents of Utah, the Clarks are members of the Church of Jesus Christ of Latter-day Saints and beneficiaries of the close family and community ties encouraged by the Mormons. Miller, their social worker, has experience in setting up networks of family and friends, what she calls "support systems," to help kidney failure patients.

"You get into a small Utah community and you get a support system you wouldn't believe," she said. When Miller took Una Loy Clark and her daughter Karen to a holiday performance of the Mormon Tabernacle Choir, many notes were passed to the two Clarks: "God bless you" and "Our prayers are with you."

"But no one really tried to violate their privacy," Miller said.

Some community residents have offered houses to the Clarks, one in particular, which is conveniently built on one level so that Clark can easily move around. Only a few air ducts would have to be installed to accommodate the machine that drives the artificial heart.

Una Loy Clark has spoken enthusiastically to Miller about being able to cook with salt again, now that her husband has a strong circulatory system. Kolff's lab is working on more portable air compressors than the 375-pound device that Clark must wheel around at the hospital. Peterson has speculated that Clark might be able to return to golf, or at least putt.

But Miller, and Clark's doctors, warn against moving too fast. "I think one of the toughest things for him in the last few weeks has been that he is not in full control of his life, as he is used to," Peterson said.

Miller said Mrs. Clark is delaying any decision about the house until her husband can participate fully. "On any kind of permanent arrangement, she is insisting on waiting until he has a say," Miller said. "He's a very decisive man."