Discussion

Double aortic arch is the most common type of vascular ring anomaly that typically manifests in infancy or early childhood with symptoms of tracheal and/or oesophageal compression.Reference Backer, Mongé, Popescu, Eltayeb, Rastatter and Rigsby ¹ Respiratory symptoms include cough, dyspnoea, recurrent pulmonary infections, stridor, and respiratory distress with feeds.Reference Griswold and Young ² Symptoms due to oesophageal compression, namely dysphagia and choking and feeding intolerance, can arise as early as the 1st year of life but usually become apparent during childhood. Although uncommon, double aortic arch can be diagnosed well into adulthood. In general, older children and adults typically present with symptoms related to oesophageal compression more commonly than respiratory symptoms. Although respiratory symptoms are reported in the neonatal period, critical tracheal compression leading to respiratory failure immediately after birth is a rare manifestation of double aortic arch.Reference Moon, Mayor and Younis ^{3 –} Reference Cannioto, Ngalikpima and Dall’Amico ⁵ Nevertheless, this can provide a diagnostic and therapeutic dilemma, owing to a widely held and generally correct notion that respiratory failure is not a typical manifestation of the disease in the immediate neonatal period. In one series of 81 children, surgical repair was necessary at a median age of 6 months, with the youngest patient repaired at 3 days of life.Reference Alsenaidi ⁶ Severe respiratory compromise has even been reported as early as fetal life, as highlighted in one case of vascular ring with a right dominant double aortic arch.Reference Shum ⁷ A strong index of suspicion is necessary.

Echocardiographic evaluation of any patients with suspected airway/oesophageal obstruction should always include the assessment of aortic arch anatomy, arch sidedness, and head and neck vessel branching pattern. In double aortic arch, the right arch is usually (72%) dominant, with the left arch commonly being hypoplastic.Reference Alsenaidi ⁶ On routine echocardiographic technique (optimal for imaging the left aortic arch) one could potentially visualise the hypoplastic left arch and miss the dominant right arch that might lead to the false impression of hypoplastic aortic arch or coarctation of aorta as described in this case. The presence of hypoplastic aortic arch without any other echocardiographic evidence of arch obstruction (e.g. right heart dilation) should lead to the suspicion for double aortic arch prompting one to look for the dominant right arch.

The decision to proceed to surgical intervention was based on judicious diagnostic workup and the ability to demonstrate the tracheal compression and stenosis due to the vascular ring by dynamic airway evaluation on CT imaging. The dynamic CT airway evaluation was helpful in identifying the degree of associated airway abnormalities (such as tracheomalacia) and ruling out other possibilities of airway compromise. The degree of tracheomalacia did not appear severe enough by dynamic airway evaluation to warrant surgical intervention specific to the airway; therefore, the surgical planning was primarily directed at alleviating the vascular ring. A few case reports are available that demonstrate the utility of dynamic airway evaluation in the diagnosis and management of tracheal compression in infants with vascular ring anomalies.Reference Rogalla, Wauer and Rogalla ^{8 –} Reference Gaafar and El-Noueam ¹⁰ With current dose modulation techniques, the radiation exposure for dynamic airway evaluation can be reduced to as low as reasonably achievable and results in effective radiation doses that are not much higher than a regular chest CT, as was the case in our patient. In conclusion, we believe that an advanced imaging modality such as CT with dynamic airway evaluation provides valuable information in neonates with evidence of critical respiratory compromise from vascular rings, including double aortic arch.