Prenatal aortic arch development in double aortic arch: Understanding postnatal closure of left aortic arch: A case report.

Double aortic arch (DAA) is a rare congenital abnormality characterized by a vascular ring that often requires surgical intervention due to respiratory complications. The DAA and right aortic arch with mirror-image branches (RAA-MB) represent abnormalities in development of the aortic arch. However, prognosis differs significantly, as the DAA forms vascular rings, whereas the RAA-MB typically does not. Distinguishing between the conditions becomes particularly challenging in cases of DAA with closure of the posterior portion of the left aortic arch (LAA) because the postnatal manifestations closely resemble those of RAA-MB. Herein, we present a case of DAA in which longitudinal observation of the LAA and RAA diameters during pregnancy aimed in predicting postnatal closure of the LAA. A 37-year-old female with suspected DAA was referred to our hospital at 26 weeks of gestation. Initial measurements revealed comparable diameters for the LAA and RAA; however, the LAA diameter decreased to approximately half that of the RAA by term owing to growth restrictions. Postnatal contrast computed tomography confirmed the closure of the posterior portion of the LAA and RAA with Kommerell diverticulum. Our findings suggest that careful monitoring of DAA throughout fetal development, especially during the third trimester, may aid in predicting atretic changes in the nondominant arch after birth, allowing an easy distinction between the DAA and RAA-MB after birth.