CASE 1

A girl, born at term by caesarean section (3.9 kg birthweight) developed grunting immediately after birth. She was admitted to the special care baby unit with a diagnosis of UAO. Chest x-ray, barium swallow, echocardiogram and bronchoscopy were normal. She was discharged at 10 days of life with persistent stridor without airway compromise or feeding difficulties. She was readmitted eight days later, and was intubated and ventilated for worsening stridor. A chestx-ray revealed bilateral pulmonary oedema. She developed frequent hypoxic episodes and had two cardiopulmonary arrests, both of which were managed successfully. She had seizures and was then referred to intensive care unit. On arrival she was shocked, had biphasic wheeze, and a combined respiratory and metabolic acidosis (capillary blood gas pH 6.75, pCO₂ 27.5 kPa, pO₂ 28.7 kPa and a base deficit of 15). A chestx-ray showed bilateral diffuse shadowing with extensive air bronchogram. The echocardiogram was normal and bronchoscopy showed a slight swelling into the lumen on the right side 2 cm above the carina with some tracheomalacia. Attempts to wean her from respiratory support were unsuccessful. MRI showed a double aortic arch verified by preoperative angiography. She was successfully extubated after surgery.

CASE 2

A boy born at term (3.3 kg birthweight) developed stridor from day 2 of life. He was discharged with a diagnosis of laryngomalacia. The stridor persisted and he was readmitted at 5 weeks of age for broncholitis requiring ventilation. Extubation attempts over two weeks were unsuccessful. Chest x-ray, echocardiogram, and laryngoscopy were normal. He was referred to intensive care; on arrival he was shocked, with the arterial blood gas showing mixed respiratory and metabolic acidosis (pH 7.07, pCO₂ 11 kPa, pO₂ 9.6 kPa and a base deficit of 15). Chestx-ray was normal and an echocardiogram showed a right sided aortic arch with a possibility of a smaller left aortic arch. MRI confirmed the diagnosis ofvascular ring, which was verified by preoperative aortogram. He was extubated successfully four days later.

CASE 3

A girl born at 34 weeks of gestation (2.5 kg birthweight) remained well intil 6 days of life when she developed apnoea and cardiac arrest requiring prolonged cardiopulmonary resuscitation. She was intubated and ventilated. She developed seizures. Chest x-ray was normal and computed tomography scan of the head showed features suggestive of global ischaemia. She failed four extubation attempts because of stridor and recessions. Direct laryngoscopy showed that the cords were slightly oedomateous. At 3 weeks of age, she was transferred to intensive care. Bronchoscopy was normal and she was extubated the following day but reintubated two days later for respiratory distress. MRI showed a double aortic arch confirmed by preoperative aortogram. She made an uneventful recovery after surgery.

Double aortic arch (DAA) is the most common cause of symptomatic vascular ring and usually presents in the neonatal period with wheezing, persistent stridor, tachypnoea, dyspnoea, and dysphagia.1 A high index of suspicion is necessary as inappropriate investigations and management may delay the correct diagnosis being made, thereby exposing the patient to life threatening events. A chest x-ray may show abnormal indentation or a deviated trachea due to a prominent right aortic arch, but all our patients had normal chestx-rays. A barium swallow may show the abnormal indentations on the trachea and the oesophagus. Only case 1 had a barium swallow study and this yielded normal results. Echocardiography was reported as normal in case 1 and suggestive of the diagnosis in case 2, while bronchoscopy was normal in cases 1 and 2. MRI is an accurate and non-invasive tool for the assessment of vascular ring2 and facilitated a correct diagnosis in all cases. Angiography is also accurate but invasive and associated with a small but significant morbidity and mortality. Angiography was done preoperatively due to the surgeon’s preference.

We recommend that in a neonate with persistent UAO, a firm diagnosis must be established before hospital discharge and an MRI scan should now be part of the routine investigation of infants with serious and persistent airway obstruction.