Denton A Cooley was an innovative cardiovascular surgeon and founder of the Texas Heart Institute in Houston, Texas. He was born in Houston on 22 August 1920 to Mary Fraley Cooley and a prominent local dentist, Ralph Clarkson Cooley. His grandfather, Daniel Denton Cooley, was a successful Houston real estate developer. After graduating from Houston’s San Jacinto High School in 1937, Denton Cooley received his undergraduate training at the University of Texas at Austin. Being 6’4” and a talented basketball player, he was a key contributor to the team’s Southwest Conference championship win in 1939. Cooley would later say that basketball taught him the importance of practise, which later helped him develop his surgical skills, and of improving dexterity (as a surgical trainee, he would practise tying knots inside a matchbox), as well as ‘skills for coping with loss and disappointment,’ which he felt were important to his success as a surgeon. Cooley began his undergraduate studies intending to become a dentist like his father, but while visiting a doctor friend working at an emergency room, he learned to stitch wounds, and he subsequently changed his course of study from predental to premedical. In 1944, he received his medical degree from Johns Hopkins Medical School, where he then became a surgical intern for the pioneering congenital heart surgeon Alfred Blalock and participated in the first Blalock-Taussig ‘blue-baby’ operation – a successful treatment for an otherwise fatal condition. Later, after losing a patient to ventricular fibrillation during an emergency operation, Cooley designed a defibrillator that was used clinically at Johns Hopkins for almost a decade. Cooley went to London in 1950 to serve as a senior surgical registrar at the Brompton Hospital under the tutelage of Lord Russell Brock and Oswald Tubbs. There he participated in several ‘Brock operations’ – beating-heart procedures performed to treat congenital pulmonary valve stenosis. Cooley considered this an invaluable experience. He returned to Houston in 1951 to take a faculty position at Baylor College of Medicine’s department of surgery, under the leadership of Michael E DeBakey. While at Baylor, Cooley made many contributions to the field of cardiovascular surgery. Prominent among them was his groundbreaking work (with DeBakey) in repairing aortic aneurysms. He also, in 1957, performed the first successful carotid endarterectomy. Cooley had the opportunity to observe open-heart surgery for the first time in June 1955, when he visited pioneering heart surgeon C Walton Lillehei at the University of Minnesota. Lillehei was the first to perform meaningfully successful open-heart surgery, using cross-circulation to support paediatric patients undergoing repair of congenital heart defects (by connecting the patient’s circulatory system to that of a parent, which supported the patient during the operation). Upon returning to Houston, Cooley built a cardiopulmonary bypass machine from parts salvaged from a restaurant-supply store and performed Houston’s first successful open-heart operation in April 1956. That year, Cooley’s results in 95 open-heart surgery cases were the best in the world. This resulted in a large influx of patients, making Houston, Texas a leading centre for cardiovascular surgery. This success was attributable to Cooley’s speed and precision as a surgeon; he told his trainees that when a patient goes on the heart-lung machine, they begin to die, stressing the importance of speed in applying this technology. Because of his unparalleled experience, Cooley made many technical contributions to the field of cardiovascular surgery, participating in as many as 33 ‘firsts’. In 1961, he became the first surgeon to perform open-heart surgery on a Jehovah’s Witness. Initially, heart-lung machines were primed with blood, but in this case, Cooley substituted a 5% dextrose solution. By avoiding the use of blood as a prime, and thus reducing the amount of donated blood required, the number of open-heart procedures that could be performed increased exponentially. After the introduction of heart transplantation, Cooley performed the first successful heart transplant in the United States in May 1968. He performed 20 more such transplants – more than any other surgeon in the world at the time. Importantly, Cooley successfully implanted the first total artificial heart as a bridge to transplant in April 1969. His pioneering work in cardiac replacement continued with implanting the first left ventricular assist device as a bridge to transplant in 1978 and a second total artificial heart as a bridge to transplant in 1981. Cooley was also one of the initial premier heart valve surgeons. He developed his own heart valve in the mid-1960's, and he worked closely with Lillehei to introduce the standard-of-care bileaflet valves that are in widespread use today. Stemming from his many technical contributions to the field of cardiac surgery, he published more than 1,400 peer-reviewed articles in the medical literature. Cooley’s contributions to cardiovascular surgery were not solely technical. He was instrumental in introducing managed healthcare plans to cardiovascular services billing, which was an important step toward addressing the high cost of cardiac surgical procedures in the US. In 1962, while still a member of the Baylor faculty, Cooley founded the Texas Heart Institute: a dedicated research and education institution that was affiliated with St Luke’s Episcopal Hospital and Texas Children’s Hospital. Cooley believed that establishing the Institute was among his most important contributions to the field of cardiac care. A source of great pride to Cooley was his work in educating surgical fellows and residents. During his career, he trained 136 cardiothoracic surgery residents and 927 cardiovascular fellows. He was also a great supporter of the universities he attended and of his home city of Houston. As a result, many facilities have been named for him, including the Denton A Cooley Recreation Center at Johns Hopkins, the Denton A Cooley MD Hall at the Texas Medical Center Library, the Houston Zoo’s Denton A Cooley Animal Hospital, the Denton A Cooley Basketball Pavilion at the University of Texas at Austin, and the Denton A Cooley MD and Ralph C Cooley DDS University Life Center at University of Texas’ school of dentistry in Houston. He received many honours for his work. In 1967, he was awarded the René Leriche prize, the International Society of Surgery’s highest honour. In 1984, US President Ronald Reagan presented him with the Presidential Medal of Freedom, the highest civilian award in the United States. And in 1998, he was awarded the National Medal of Technology and Innovation by President Bill Clinton. The Royal College of Surgeons of England made Cooley an honorary fellow in 1988. This was a source of great pride to him, particularly because of his training and experience under Lord Brock and Oswald Tubbs. With his wife of 67 years, former Johns Hopkins nurse Louise Goldborough Thomas, Cooley had five daughters, 16 grandchildren and 17 great-grandchildren. Outside of Houston in Orchard, Texas, he built Cool Acres Ranch, a vacation home that became the site of many family gatherings. He continued performing open-heart operations until his early eighties. In his lifetime, his surgical group at St Luke’s completed more than 120,000 procedures with the use of cardiopulmonary bypass – more than any other team in the world. Lillehei, considered by many to be the premier cardiovascular surgeon of his time, once said that it was Cooley who deserved that title because of his early success with using cardiopulmonary bypass, rather than the cross-circulation technique Lillehei used, to support patients during the surgical correction of intracardiac defects. Denton Cooley died on 18 November 2016. He was 96.