Aberrant Subclavian Artery Origin
(RSCA crosses midline, posterior to esophagus)
Pulmonary Sling: Origin of LPA from RPA
(LPA crosses midline anterior to esophagus, inbetween esophagus & trachea)
(Diagrams below are from Esophagography in Anomalies of Aortic Arch System. A.C. Klinkhamer. The Williams & Wilkins Company, Baltimore MD. 1996)
How to use the Table:
1. First, review plain CXR (PA view; High dose film) - Ascertain aortic arch sidedness & position of descending aorta in thorax.
2. Second, study Barium Swallow Study - Usually Frontal and Oblique views (Note: Lateral view is ideal for Pulmonary sling and Double aortic arch, but not useful in other anomalies)
Image source: Esophagography in anomalies of the aortic arch system. A.C. Klinkhamer. The Williams & Wilkins Company, Baltimore, MD. 1969. Copyright - Excerpta Medica Foundation.
Related link: Barium Swallow