Isolated anomalies of the branch pulmonary arteries are rare, more often occurring in the setting of complex congenital heart disease. These isolated anomalies are often not identified in the prenatal period. We describe two cases of isolated anomalies of the left pulmonary artery which were identified on fetal echocardiography and confirmed postnatally, an anomalous left pulmonary artery arising from the base of the left-sided brachiocephalic artery in the setting of a right-sided aortic arch, and a left pulmonary artery sling. These two cases support our current understanding of normal and abnormal development of the extrapericardial arterial vessels and highlight the importance of meticulous attention when sweeping from the three-vessel tracheal view.
