EP09.06: A case of incomplete double aortic arch with steep RF angle between aortic arch and first branch

Double aortic arch (DAA) is a congenital vascular anomaly in which the airway is compressed by the residual presence of both the right aortic arch (RAA) and left aortic arch (LAA), causing respiratory problems from early life. DAA with LAA atresia is termed an incomplete DAA (iDAA). It is difficult to diagnose iDAA because of the interruption of blood flow during perinatal period. We have previously reported that DAA is associated with a steep angle between the RAA and the first branch (RF angle: <71 degree). In this report, we describe a case in which the RF angle was steep on prenatal fetal echocardiography, and iDAA was diagnosed after birth. The mother was referred to our hospital due to excessive amniotic fluid at 29 weeks gestation. Fetal echocardiography showed RAA and left ductus arteriosus. The fetus has steep RF angle of 57 degrees and was suspected iDAA. He was born at 36 weeks of gestational age and the contrast-enhanced CT scan showed that the left brachiocephalic artery was pulled backwards and reached almost to the descending aorta which fit the diagnosis of iDAA. Because of the postnatal symptoms of inspiratory stridor and compression findings on esophagography, lateral thoracotomy surgery was performed on his 16th day, and iDAA was diagnosed based on intraoperative findings. The diagnosis of iDAA is difficult especially in the fetal period. Usually, iDAA is suspected by the presence of respiratory disturbance, symmetrical origin of subclavian artery and common carotid artery, steeper posterior traction of the first branch of RAA due to ligament. In this case, the fetus has RAA and suspected iDAA due to steep RF angle during perinatal period. Finally, he reached early diagnosis of iDAA after birth. In conclusion, steep RF angle in a case of RAA suggests the possibility of iDAA.