The most common form of
vascular ring compression is PRAA with absence of the
left arch. The intersegmentals are pulled forward along the aorta as
usual but the left arch instead of the right arch separates from the dorsal
aorta. Consequently, the right 4th aortic arch, left-sided ductus arteriosus and
pulmonary artery form a vascular ring around the esophagus and trachea.
The esophageal compression is relieved by dividing the ductus (or ligamentum