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Clarence Dennis

Dr. Clarence Dennis

Dr. Clarence Dennis, pioneer in open heart surgery, dies

Memorialized Friday as inventive and curious

By Deane Morrison

Published on September 15, 2004

It was typical of Dr. Clarence Dennis to invent whatever was needed to get a job done. In April 1951, the University of Minnesota Hospital surgeon hooked up a 6-year-old girl to a new heart-lung machine he had invented and performed the world's first open heart surgery. Unfortunately, the patient died because her heart defect turned out to be much more severe than expected, but the machine, which kept her blood oxygenated the whole time, worked well and opened the door to new developments in heart-lung machines and heart surgery. An inquisitive and inventive scientist to the end, Dennis, 96, died July 11 in his hometown of St. Paul. On Friday, September 16, the University held a memorial service in Mayo Auditorium. A reception followed at Nils Hasselmo Hall.

"He was a very inventive guy," says University transplant surgeon John Najarian. "Everything was a challenge to him, and he met that challenge." Besides his other inventions, he had a patent on a bread slicer, Najarian says.

Dennis was born June 16, 1909, in St. Paul. He graduated from Central High School in 1927 and from Harvard in 1931. He earned an M.D. at Johns Hopkins in 1935 and a master's degree in physiology and doctorate in surgery from the University of Minnesota in 1940. Two weeks after performing the first open heart operation, Dennis undertook the second. Again, the pump worked perfectly, but the patient died of an embolism when a technician failed to notice that air had entered the bloodstream. In summer 1951, Dennis left the University for the surgery department at the State University of New York (SUNY) Down State Medical Center in Brooklyn, a department he would chair for 20 years. He was all set to continue his work, but doctors who had promised him patients changed their minds. But eventually, on June 30, 1955, he became the second surgeon to perform a successful open heart operation using a heart-lung machine. In that operation, he cured a defect in the wall separating the two atria of the heart. His achievement followed the success of Dr. John Gibbon at Jefferson Hospital in Philadelphia, with whom Dennis had been collaborating since 1945. In 1972, Dennis became director of the Division of Technological Applications at the National Heart and Lung Institute of the National Institutes of Health, where he worked on the artificial heart program. In 1974 he left for SUNY Stony Brook, where he researched gastrointestinal obstruction and wound closures. Along the way, he invented many other surgical devices, including the Dennis clamp for connecting pieces of bowel and the Dennis tube for sucking out stomach contents. He also invented a device to help failing hearts pump blood. Although not successful enough to gain wide acceptance, it stimulated others to develop a ventricular assist device, or VAD, that is now in use. He retired in 1988. In 1991 Dennis returned to the University of Minnesota to head the Cancer Detection Center, one of the first clinics devoted to preventing cancer or detecting it very early through comprehensive screening. He retired a second time in 1996. "He was a very inventive guy," says University transplant surgeon John Najarian. "Everything was a challenge to him, and he met that challenge." Besides his other inventions, he had a patent on a bread slicer, Najarian says. Another invention stemmed from Dennis's vision problems in his later years, says David Rothenberger, interim chair of the University's surgery department. "Clarence used to come to grand rounds as an older, retired surgeon," Rothenberger recollects. "He was having trouble seeing the slides that were presented, so he came up with a hood that had a battery-powered attachment. It was a compact video camera that projected images from the big screen inside his hood. He made his own little projection booth." The memorial will feature reminiscences and tributes by family, University faculty, and former colleagues. "It should be a fun event because that's the way he wanted it," says Rothenberger.

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