Clarence Dennis, MD, PhD, a pioneer cardiac surgeon and investigator, died on July 11, 2005, at age 96. Born in St. Paul, Minnesota, Clarence graduated from Central High School in St. Paul and then attended Harvard. He received his degree in medicine from Johns Hopkins University in 1935 and began postgraduate surgical education at the University of Minnesota under Dr. Owen Wangensteen, where he received a PhD and in 1947 became a full professor of surgery.
After receiving a grant from the fledgling National Institutes of Health, he began research developing a pump and oxygenator apparatus to attempt open heart surgery. He achieved preliminary success with the device in the animal laboratory and then decided to attempt clinical application. On April 6, 1951, he operated on a child with congenital heart disease. The patient's heart had previously been explored by Dr. Richard Varco, who had inserted his finger into the left atrium through the appendage and discovered a septal defect. At Dennis's operation, done later using the apparatus with a double vertical screen oxygenator, a complex atrioventricular canal defect was found and was considered uncorrectable. The patient died. In an attempt to close a simple isolated atrial defect in another patient, the blood reservoir in the circuit emptied and that patient died also. Not long thereafter, in 1951, Dr. Dennis moved to Downstate Medical Center at State University of New York (SUNY), where he continued his efforts to perform open heart surgery. In June 1955, he performed the first successful open heart operation in New York State, closing an atrial defect. Dr. John Gibbon of Jefferson College had performed the first successful case of this type in 1953, which had stimulated Dennis's determination.
Dr. Dennis became Chairman of Surgery at Downstate and Surgeon-in-Chief at Kings County Hospital Center, where he provided a strong stimulus to his colleagues, including Karl Karlson, Phillip Sawyer, Martin Kaplett, and others.
Dennis's interests and investigations in cardiovascular surgery ranged widely, and he was supported by NIH funding from 1947 to 1972. Left heart bypass techniques were used clinically for the support of patients with myocardial infarction, decompensation, and pulmonary edema, with limited success. He designed a caged-ball valve prosthesis, which he implanted in the mitral position in dogs, without success. He also investigated counterpulsation for cardiac decompensation and gas endarterectomy for arterial disease.
Throughout his academic career, Dennis devoted efforts toward research and education and was highly regarded by his peers. After his retirement in 1988, he continued to develop inventions in his home laboratory in St. Paul. In later years, he suffered from visual loss. In 1991, he became director of a cancer detection center and retired again in 1996.
Reflection on cardiac surgery during the past 60 years reveals the striking evolution of diagnostic and other techniques that have increased the safety and predictability of modern open heart procedures. Clarence Dennis is an important part of that history.
Denton A. Cooley, MD
President, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston