This patient in the first year of life has a rare congenital malformation. The upper lobe branch of the left pulmonary artery has a typical anatomy from the bifurcation of the pulmonary artery, but the left lower lobe branch arises from the right pulmonary artery. It originates below the level of the right lower lobe bronchus. It is located between the esophagus and the left main bronchus and does not compress them. In relation to the left main bronchus, it courses below and behind, has a parallel course and is not aberrant. Therefore, this case cannot be called a pulmonary sling.