EP09.18: Utility of the angle between the right aortic arch and first branch for detecting double aortic arch via fetal echocardiography

A double aortic arch (DAA) is an aortic arch anomaly most frequently associated with the development of airway and esophageal compression after birth. Incomplete DAA, atresia of one aortic arch result in a non-patent fibrous cord, is particularly difficult to differentiate from and right aortic arch with mirror image branching (mRAA) that is rarely causes tracheal compressive symptoms. The present study aimed to evaluate the differences between DAA and mRAA by fetal echocardiography. The present retrospective cohort study included all patients diagnosed with complete DAA, incomplete DAA, or mRAA between 2010 and 2023.The patients were divided into the DAA and mRAA groups. We compared the groups based on the following outcomes: (1) the angle between the right aortic arch and first branch (RF angle); (2) ratio of height to width of the region bounded by the aortic arch, first branch of the aortic arch, and descending aorta (RF ratio); and (3) the maximum tracheal diameter on a three-vessel trachea view. Nine cases were included in the DAA (five complete DAA and four incomplete DAA) and four cases were included in the mRAA groups, respectively. All DAA cases were underwent surgery after birth. Among them, all incomplete DAA cases could not be diagnosed via fetal echocardiography and were diagnosed intraoperatively. On fetal echocardiography, the RF angle was significantly sharper in the DAA group than in the mRAA group (median 57(36–69) vs. 75 (62–94); p < 0.05), maximum tracheal diameter (median 2.2 (1.4–3.3) vs. 3.2 (2.8–3.5) mm; p < 0.05). There was no significant difference in the RF ratio (median 0.60 (0.41–0.77) vs. 0.70 (0.42–0.76)). The ROC curve analysis showed a cut-off value of 71°, and an RF angle of <71° had 100% sensitivity and 75% specificity for the detection of DAA. The DAA group had a steeper RF angle than the mRAA group. The cut-off value for diagnosing DAA was an RF angle of <71°.