A further problem arises when the ductus arteriosus closes, causing severe cyanosis. The infant is then usually given prostaglandin to keep the ductus arteriosus open. As a palliative measure, a surgeon may create a shunt between the pulmonary artery and the aorta to increase blood flow to the lungs. If the right ventricle is too small to be effective as a pump, a Fontan procedure is performed later, connecting the right atrium directly to the pulmonary artery. The ASD or PFO is also closed to relieve the cyanosis.
Blood can reach the pulmonary arteries only through a patent ductus arteriosus.