When does an aberrant right subclavian artery create a vascular ring?

To describe the rare combination of findings where a left aortic arch and aberrant right subclavian artery are associated with a vascular ring, which is in the setting of a right-sided arterial duct.

Analysis of all prenatally diagnosed cases of left aortic arch and right-sided arterial duct (between 2016 and 2025) at three fetal cardiac centres (2 UK and 1 Austrian) with documentation of aortic arch branching pattern.

In 5/6 cases, aberrant right subclavian artery was identified. Genetic abnormality was identified in 50% of cases (22q11 microdeletion). Three fetuses had a ventricular septal defects, and two cases had vascular abnormalities (with further characterisation on postnatal CT). No fetuses had extracardiac abnormalities.

Left aortic arch with aberrant right subclavian artery is not uncommon in the general population but when associated with other abnormalities may also be a marker for chromosomal and genetic abnormalities. If not fully understood, patients may be incorrectly counselled regarding the likelihood of respiratory and swallowing symptoms of a vascular ring. An understanding of the circumstances in which a ring can arise is needed. Our study adds to the limited published data on this condition, with a view to improving clinician understanding and guiding accurate prenatal counselling.