(1895–1988), French-born American physiologist and Nobel laureate, born in Paris and educated at the Sorbonne and at the Medical School of the University of Paris. After serving in World War I, and obtaining his medical degree (1930), Cournand went to the U.S. to work as a resident in the Tuberculosis (later Chest) Service of the Columbia University Division at Bellevue Hospital in New York. He also taught at the College of Physicians and Surgeons of Columbia University (1934–64). In 1941 he became a U.S. citizen.

At Bellevue Hospital in 1935 Cournand joined American physician Dickinson W. Richards in research on respiration and circulation. They built on the work of German physician Werner T. O. Forssmann, who had devised a method of heart catheterization, in order to measure blood pressure in the heart and blood flow through the lungs. While at Bellevue, before and during World War II, Cournand studied secondary wound shock and its treatment for the U.S. government, showing that cardiac catheterization could serve as a means of blood transfusion in cases of shock.

Cournand expanded the catheterization techniques he had worked out to research on the lungs, making the first measurements of pulmonary artery blood pressure and discovering that pulmonary circulation responds to the oxygen content of the blood in the small arteries. When the oxygen content is low, these small arteries constrict, and blood pressure rises. He also did pioneer research on infants and children with a variety of congenital and pathological heart diseases (see Diagnosis.).

Cournand shared the 1956 Nobel Prize in physiology or medicine with Forssmann and Richards for “their discoveries concerning heart catheterization and pathological changes in the circulatory system.”

He wrote From Roots to Late Budding: The Intellectual Adventures of a Medical Scientist (1985).