Anna the dog

Dog

The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

 was the first survivor of pulmonary bypass surgery, considered an experimental procedure at the time.

Operated on by Dr. Alfred Blalock

Alfred Blalock

Alfred Blalock was a 20th-century American surgeon most noted for his research on the medical condition of shock and the development of the Blalock-Taussig Shunt, surgical relief of the cyanosis from Tetralogy of Fallot—known commonly as the blue baby syndrome—with Vivien Thomas and pediatric...

 and his assistant Vivien Thomas

Vivien Thomas

Vivien Theodore Thomas was an African-American surgical technician who developed the procedures used to treat blue baby syndrome in the 1940s...

, Anna survived the first pulmonary bypass after having been operated on twice. The second operation was required to replace the original stitches with flexible ones. Dr. Blalock and Thomas were trying to find a way to cure 'blue babies', or babies whose pulmonary arteries

Pulmonary artery

The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....

 were blocked, limiting oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 supply to their blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

. After their success with Anna, Blalock and Thomas had the courage to perform the very first open heart surgery

Open Heart Surgery

Open Heart Surgery was released on August 8, 2000 by rock band Virginwool. The band signed to Breaking/Atlantic Records after initially beginning signed to Universal Records. The album was produced and mixed by Brad Wood....

 on Eileen Saxon

Eileen Saxon

Eileen Saxon was an infant known as "The Blue Baby", because of a condition called Tetralogy of Fallot, one of the primary congenital defects that lead to blue baby syndrome. In this condition, defects in the great vessels and wall of the heart lead to a chronic lack of oxygen in the blood...

in 1944.