Aberrant left pulmonary artery - pulmonary sling

The heart is normal in size and positioned in the right side of the mediastinum. The cardiac apex is directed to the right with the left ventricle located anteriorly and still to the left of the right ventricle. There is atrio-ventricular and ventriculo-arterial concordance. These findings are more in keeping withreflective of cardiac dextroversion. The atria and ventricles are normal in size without dilatation or hypertrophy of the musculature.

A single right-sided aortic root is detected with its arch coursing from right to left anterior to trachea. The descending aorta is left-sided. There is minimal denting of the anterior aspect of the mid trachea as the arch crosses the trachea.

The pulmonary trunk, measuring 1.4 cm in widest transverse diameter, is larger than the aortic root , which measures 1 cm. The right pulmonary artery branch measures 0.5 cm. The left pulmonary artery branch emanates from the right pulmonary artery and courses behind the trachea at the level of the carina and anterior to the esophagus. This area of crossing along the distal trachea causes mild narrowing of the lumen.  These findings are consistent with pulmonary sling. 

The inferior vena cava, right and persistent left superior vena cavae drain into the right atrium.

The trachea is midline in location. The tracheal stenosis at the mid segment is approximately 30% due to the above-mentioned crossing of the aortic arch. The pulmonary sling described above causes approximately 16% distal tracheal stenosis. There is also narrowing at the branch point of the right main stem bronchus.

Both lungs show mosaic pattern of attenuation suggestive of air trapping.