Aberrant Subclavian Artery in Interrupted Aortic Arch with Severe Aortic Outlet Obstruction: Cerebral Blood Flow as a Possible Determinant of Embryonic Cardiovascular Development?

Background: Aberrant subclavian artery (ASCA) is frequently observed in interrupted aortic arch (IAA) with aortic/subaortic obstruction. Developmental significance of ASCA in IAA in utero remains elusive. Methods: Newborns with prenatally diagnosed isolated IAA under continuous prostaglandin E1 infusion were studied. Cross-sectional areas of aortic valve opening (AVO CSA ) and patent ductus arteriosus (PDA CSA ) were represented by echocardiographic measurement of (diameter) 2 indexed by body surface area (m 2 ). Types of IAA and presence of ASCA were examined in relation to sizes of AVO CSA and PDA CSA . Results: Twenty-four newborns with IAA (six type A and 18 type B) were reviewed. Male dominance was seen in type B (male 72%). Twenty-three patients had left aortic arch. No type A patients had ASCA, but 50% of type B had ASCA; AVO CSA was significantly smaller in type B than in type A ( p  = 0.003). In type B, PDA CSA was significantly larger in those with ASCA than without ( p  = 0.003), but AVO CSA exhibited no significant size difference between these two subgroups. Chromosome 22q11 deletion was only seen in type B (56%) and showed no significant correlation with the presence of ASCA. Conclusions: In type B IAA, the presence of ASCA was associated with larger PDA CSA , suggesting an adaptive enlargement of the ductus arteriosus and ASCA in response to reduced antegrade flow across small AVO CSA , which may be augmenting cerebral blood flow. Preservation of cerebral blood flow may be another important determinant affecting embryonic cardiovascular development.