ACR Codes: 5.1
A double aortic arch is a vascular ring, a congenital malformation in which the trachea and the esophagus are surrounded by connecting segments of the aorta and its branches. Both a right and left sided aortic arch are present. During embryogenesis, the third, fourth and sixth pharyngeal arches become the primary contributors to the aortic arch. Normally, segments of the developing aortic arch regress, leading to a unilateral structure. A double aortic arch is formed when both fourth pharyngeal arches and dorsal aortas fail to regress. Both arches may remain patent, or one may be atretic. The right arch is more commonly superior than the left, and in 75% of patients, the right arch is dominant. The double aortic arch often occurs with other cardiovascular defects. These include ventricular septal defects and tetrology of Fallot. Truncus arteriosis, transposition of the great arteries and pulmonary atresia are also associated with double aortic arches. Congenital heart defects occur in 1 in 120 live births. Vascular rings account for less than 1% of congenital heart problems, and 45%-65% of patients undergoing surgical repair for a vascular ring have a double aortic arch.
DiGeorge Syndrome, a genetic disease caused by a deletion of chromosome band 22q11, has been associated a double aortic arch. Around 20% of patients with a double aortic arch will also have a deletion of 22q11. Close to 80% of DiGeorge syndrome patients have some form of cardiac defect; including VSD,Tetrology of Fallot, persistent truncus arteriosus and a double aortic arch. DiGeorge syndrome may also present with an absent thymus, palatal abnormalities, laryngotracheal defects, learning difficulties, renal anomalies, hearing loss and speech delays, seizures, hypocalcemia, T-cell mediated immunity and neurologic defects. The chromosomal association also extends to CATCH-22 syndrome. Due to the above relationships, patients with a double aortic arch may also present with any of the above. A double aortic arch may also be associated with esophageal atresia.
As a vascular ring, a double aortic arch may lead to compression of the trachea and esophagus, impairing respirations and causing difficulty swallowing. It has been estimated that double aortic arches make up about one percent of cardiovascular malformations. The incidence of a double aortic arch is unknown. Double aortic arches tend to present earlier than other vascular rings. Parents may notice noisy breathing and patients may experience an apparent life threatening event (ALTE). Patients may also experience choking, emesis or dysphagia. There are no clinical findings specific for a double aortic arch. Physicians may observe stridor that is worse with agitation and does not improve with nebulizer treatments.
A differential includes, but is not limited to: Asthma, RSV infection, subglottic stenosis, tracheomalacia and a right aortic arch.
Physicians should remember that the diagnosis of infection does not rule out a double aortic arch. Patients with recurrent respiratory symptoms may need further evaluation. In patients with a double arch, it may be worthwhile to obtain a FISH test to look for a deletion on chromosome 22, due to the association between DiGeorge syndrome and a double aortic arch.
Imaging on chest x-ray may indicate a vascular ring with lateral indentation of the trachea. If one is suspected, a physician can use echocardiography to reliably show a double aortic arch. MRI and CT are the best modalities to diagnose and characterize double aortic arches. They will demonstrate the location of the vessels along with any tracheal or esophageal obstruction. Cardiac catheterization, barium esophagography and EKGâ€™s are not indicated for a double aortic arch.
Surgery is indicated to repair a double aortic arch in patients with symptoms of airway or esophageal obstruction and if patients are already undergoing surgical repair of associated anomalies.