An atrial septal defect, or ASD, is a hole in the wall between the atria, the two upper chambers of the heart. Such holes vary in size, and small holes may close on their own without surgical intervention or may not cause a problem. About 1 in every 1,859 babies is born with an ASD.
An ASD increases the amount of blood that flows through the lungs and over time. As such, the defect may cause damage to the blood vessels in the lungs.
In the early 1950s, surgeons pioneered ways to repair ASDs using hypothermia to cool the body and prevent damage to organs such as the brain. During these surgeries, the patient’s body temperature would be lowered to 82 degrees Fahrenheit by use of a cooling blanket. The patient’s chest would be opened and the blood vessels and pulmonary artery clamped to provide a bloodless field. Working quickly, within around six minutes, a skilled surgeon could close the hole. The child’s heart would be closed, and they would be warmed up and allowed to recover. These surgeries were curative.