Pulmonary artery sling: An incidental finding

A previously healthy one-month infant was referred to our institution due to a heart murmur. The transthoracic echocardiogram showed the pulmonary trunk giving rise to the right pulmonary artery (RPA), but the left pulmonary artery (LPA) was not identified in its usual location. Instead the LPA was arising from the RPA and coursing leftward behind the trachea, with a turbulent flow (peak velocity 1.5 m/s) (Video 1). An associated ostium secundum atrial septal defect was diagnosed. The suspected diagnosis of pulmonary artery sling was confirmed by computed tomographic angiography. The LPA was seen originating from the posterior aspect of the RPA and coursing over the right mainstem bronchus and then from right to left, posterior to the trachea and anterior to the esophagus, to reach the hilum of the left lung, and causing a mild compression of the origin of the LPA (Figure 1). Besides the pulmonary artery sling and the atrial septal defect, a partial anomalous pulmonary venous return was identified, with the left superior pulmonary vein draining in the left brachiocephalic vein (Figure 2). The anomalous origin of the LPA known as pulmonary artery sling is a rare form of vascular ring. In the vast majority of patients it is associated with respiratory symptoms in the first year of life, due to tracheal stenosis, and with a