While this was going on, Taussig observed that infants with cyanotic heart defects such as Tetralogy of Fallot or pulmonary atresia often fared remarkably better if they also had a patent ductus arteriosus, with less severe symptoms and longer survival. In general, cyanotic symptoms would often begin or worsen shortly after birth, a change which Taussig suspected was caused by the natural closure of the ductus arteriosus. In cyanotic children, bloodflow from the heart to the lungs via the pulmonary artery is often compromised; Taussig thought that surgically creating an artificial ductus linking these two vessels could increase bloodflow to the lungs and alleviate this problem, increasing survival. She broached the idea to Robert Gross, and he was skeptical, reportedly telling her ""I have enough trouble closing the ductus arteriosus. I certainly don’t want to try to make an artificial one."