Management of Prenatally Diagnosed Isolated Right Aortic Arch

The existence of a right aortic arch integrates nosologically into the group of aortic vascular arch anomalies. In the majority of cases, a right aortic arch is associated with cono-truncal congenital heart diseases (CHD), such as tetralogy of Fallot, pulmonary atresia with ventricular septal defect, and truncus arteriosus. Sometimes, a right aortic arch can be isolated, with an incidence of 0.05% to 0.1 %. Therefore, an assessment of the anatomy is necessary because an isolated right aortic arch can be associated with an encircling aortic arch anomaly and may subsequently have a functional repercussion, creating a digestive obstacle (oesophageal compression) and/or a respiratory obstacle (tracheal compression).

Furthermore, indications for surgery in this type of abnormalities are not well-established.

The diagnosis of a vascular artery anomaly is currently mostly made prenatally, with increasing diagnostic accuracy. Indeed, the application of the "3VT view" (e.g. three vessels and tracheae view) in routine prenatal sonographic screening for CHD has contributed to a better identification of such anomalies.

Prenatal diagnosis of an isolated right aortic arch involves the identification of the following aspects: the existence of a left ductus arteriosus may relate to an increased risk of an encircling aortic arch anomaly at birth; the analysis of the different vessels of the aortic arch, which can be difficult because of the fetal circulation and the maternal-fetal conditions of the examination; and the absence of a thymus, which suggests the existence of a genetic anomaly, such as DiGeorge syndrome.

After birth, the evaluation of the functional repercussion of the anomaly remains complex. The incidence of secondary symptoms to encircling abnormalities is estimated at 25%, but varies according to the anomaly: it is very frequent in case of a double aortic arch, variable in case of a right aortic arch with left ductus arteriosus (from 9% to 47% in the literature), absent in case of right aortic arch with right ductus arteriosus. Postnatal echocardiography can only assess the existence of a right aortic arch and check ductus arteriosus closure. The complete anatomical diagnosis of a vascular artery anomaly can only be made by slice cardiac imaging (CT scan or MRI), but in practice these examinations are not routinely performed in the absence of neonatal symptoms.

The aim of this study is to evaluate the accuracy of prenatally diagnosed isolated right aortic arch in terms of anatomy and functional prognosis.

The secondary aims are :

* to specify the association of an isolated right aortic arch with a genetic anomaly, * to define the role of CT scan in children prenatally diagnosed with right aortic arch, in terms of diagnosis, prognosis and follow-up, * to evaluate the incidence of respiratory and digestive complications in the first year of life, * to evaluate the indications for surgical management during the first year of life.