Dr. Kolff's first work on the artificial heart began in 1957 at the Cleveland Clinic in Ohio. In 1967, he became head of the division of artificial organs at the University of Utah and director of the Institute of Biomedical Engineering.

Dr. Kolff once told a reporter his mind rarely took a rest from the mechanics of medical-device designs and how they could save or improve lives. "I nearly always do something. I can't bear to just lie in the sun. It would drive me crazy," he said.

Researchers at the U. during his tenure there reported it wasn't unusual to see him there at work any time of the day or night.

As a young man, Dr. Kolff worked with his hands as a carpenter on weekends, finding solutions to challenges that would provide the foundation for his future work with mechanical devices.

Dr. Kolff donated his papers to the University of Utah, giving the school a collection that provides a history of his inventions as well as glimpses into his personal life.

Dr. Donald Olsen, a former colleague and director of the Utah Artificial Heart Institute, said Dr. Kolff's work influenced most of those working today in artificial organs research.

"They either worked at some time in his lab, or he worked with them on site," Olsen said. "His influence continues to be recognized worldwide. ... His legacy is gigantic when you consider all the contributions that he has made to medicine and biomedical engineering. His list of inventions that have been used clinically in patients is very lengthy."

Olsen said his colleague's most admirable trait was the ability to "recognize new technologies and find an immediate application to his own research. He also recognized talent, so that over the years he developed a tremendously important team of researchers."

Olsen said Dr. Kolff was a "tough boss, but a fair one," who expected researchers to make convincing arguments based on evidence rather than speculation.

Dr. Kolff officially resigned his position at the U. in 1983, but he remained as acting director of the U. institute until his 65th birthday in February 1986.

He was an active advocate for abortion rights and against nuclear weapons, and enjoyed nature and art.

Dr. Kolff is survived by his five children, 12 grandchildren and six great-grandchildren. His son, Jack, said the family has tentative plans for a memorial service on March 7 but details are pending. Dr. Kolff requested that his body be cremated.

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