Aortopulmonary Window is a rare heart congenital (present at birth) defect that contains a hole connecting the aorta (major artery taking blood from the heart to the body) and the pulmonary artery (the one taking blood from the heart to the lungs ). This birth defect in babies causes huge blood pressure in the lungs and can lead to congestive heart failure. The condition usually treated with open-heart surgery to repair the defect. During the procedure, a heart-lung machine takes over the circulation of the child’s heart. The surgeon starts by opening the aorta and closes the defect with a path made either from a piece of the sac that encloses the heart (the pericardium) or a man-made material.