That's a feature in the CardioWest heart, which has been implanted in more than 600 patients, usually as a bridge to human heart transplant. That heart came after the Jarvik-7, with slight modifications. In recent years, with its portable pneumatic driver, patients have survived an additional two years. Those who used it as a bridge to transplant have lived even longer.

Veterinarian Olsen was another core member of a team that over the years included hundreds of people. He was brought in first as a consultant in the late '60s, then hired to the team in the '70s because, at the time, "all the animals were dying."

He proved more versatile than imagined, even talking a mortgage company into donating the old hospital to the artificial heart effort. The team used St. Mark's old operating rooms on the top floor to implant devices in the animals. Olsen also proved to be a creative optimist. When a skeptic said that a pneumatic artificial heart would be defeated by atmospheric pressure, Olsen drove a sheep with an artificial heart to Snowbird and took pictures.

In the months following Clark's heart implant, surgical teams from around the world wanted to learn how to put the artificial heart into people. The FDA approved 27 teams, 23 of which Olsen says he personally trained, using calves as patients.

Five years after Clark's death, a total artificial heart was used for the first time as a bridge to transplant, implanted by Dr. Jack Copeland of Tucson, one of the bright lights coming to Utah this weekend.

Use of artificial heart technology has continued. LDS Hospital, for instance, implanted eight over the years, six of them as a temporary lifesaving bridge for patients awaiting human hearts.

Clark suffered perhaps more than anyone expected, with a heart malfunction at one point, seizures at another. His lung tissue was a mess, and bleeding and clots were major complications.

But he survived for three months.

"Before, we had some experience with cardiac support but had never removed a heart and never supported it for more than a day or two," Anderson says. "Clark's surgery showed you could support total cardiac function for an extended period of time."

Despite the complications, it was "revolutionary," he says.

The surgery was hotly debated: "Clark was too sick." "The device was not ready," critics said.

"But you have to at some point take a first step," Anderson says. "This was proof of principle."

"We were criticized for making a 'circus' out of the whole thing. That's the other side of being open. We thought we had to be open to avoid misconceptions," says Peterson. It was not like the experiments researchers do with mice.

That it involved a man, he says, made a huge difference.