Dr. Gordon Murray’s first application of Heparin—and its ability to control clotting and blood flow –was to pioneer the reparation of damaged arteries and veins of TGH patients, capturing the attention of the press and other surgeons around the world. He next turned to heart valves and in 1946, the particular problem of "Blue Babies," whose blood was not properly oxygenated because of heart defects.
Murray's first "Blue Baby" operation, which involved re-routing an artery from the heart to the lungs, conducted at the Wellesley Hospital, was not successful. His second attempt, performed at the TGH a few months later, proved to be a glorious success, attracting considerable media attention. Encouraged, Murray focused on trying to repair the damaged heart itself without seeing it directly, tediously inserting a needle through the septum of the heart, taking care not to puncture the coronary arteries. In June 1948, Murray again made headlines after he successfully repaired heart defects in four children; a surgical first. Between 1946 and 1951, Murray performed almost 600 heart operations, often performing two "blue baby" operations a day.