In the 1950s, Cooley returned to Houston to become associate professor of surgery at
Baylor College of Medicine and to work at its affiliate institution,
The Methodist Hospital. Cooley began working with American cardiac surgeon, scientist, and medical educator
Michael E. DeBakey. During this time, he worked on developing a new method of removing
aortic aneurysms, the bulging weak spots that may develop in the wall of the artery. In 1960, Cooley moved his practice to St. Luke's Episcopal Hospital while continuing to teach at Baylor. In 1962, he founded
The Texas Heart Institute with private funds and, following a dispute with DeBakey, resigned his position at Baylor in 1969. His skill as a surgeon was demonstrated by successfully performing numerous
bloodless open-heart surgeries on
Jehovah's Witnesses patients beginning in the early 1960s. He and his colleagues worked on developing new artificial heart valves from 1962 to 1967. During that period, mortality for heart valve transplants fell from 70% to 8%. In 1969, he became the first heart surgeon to implant an
artificial heart designed by
Domingo Liotta in a man, Haskell Karp, who lived for 65 hours. The next year, in 1970, "he performed the first implantation of an artificial heart in a human when no heart replacement was immediately available." During the
2000 U.S. presidential election, Cooley was asked by then-candidate
George W. Bush to review vice-presidential candidate
Dick Cheney's medical records, particularly concerning the status of his chronic heart condition. == Personal life ==