Dr. Robert Edward Gross at the Children's Hospital in Boston performed the first operation for patent ductus arteriosus, a congenital heart defect in which the ductus arteriosus, a special blood vessel in the fetus that allows circulation to bypass the lungs and go directly to the aorta, fails to close normally around 15 hours after birth. His patient was a seven-year-old girl named Lorraine Sweeney. Gross and Dr. John Perry Hubbard worked on dogs and other animals in order to perfect the procedure for use in humans.