Vascular ring: Unmasked

TLDR: A 3-year-old boy was admitted to a secondary hospital with 1week history of cough, lethargy and increased work of breathing, and was diagnosed and treated for a left-sided pneumonia, which improved clinically and radiographically after 2 days of intravenous benzylpenicillin.

Abstract: A 3-year-old boy was admitted to a secondary hospital with 1week history of cough, lethargy and increased work of breathing. He was diagnosed and treated for a left-sided pneumonia, which improved clinically and radiographically after 2 days of intravenous benzylpenicillin. After 8 days of improvement, he developed acute respiratory distress, with decrease in oxygen saturation to 80%. A repeat chest X-ray showed right upper lobe consolidation. He was transferred to a tertiary paediatric hospital with a diagnosis of ongoing pneumonia. The respiratory consultant at the tertiary hospital noted an obstructive breathing pattern and considered inhaled foreign body in the differential diagnoses. Hence, a chest computed tomography (CT) scan was performed, which showed a possible 8 × 4 mm foreign body obstructing the right lower lobe bronchus, as well as obstruction of the left upper lobe bronchus and partial atelectasis of the lingula and left lower lobe. A right-sided aortic arch was also noted. Because of an acute deterioration, the patient had an emergency laryngotracheobronchoscopy, during which the child was clinically very unstable. A nut foreign body was identified in the right main bronchus, which fragmented on attempted removal. Copious bleeding and secretions made removal difficult and there were major ventilation issues throughout the procedure. The surgeon suspected that all foreign bodies had not been removed. At no time was evidence of airway narrowing noted, perhaps because of the extreme difficulties encountered during the bronchoscopy. On extubation, the patient had profound desaturations, requiring re-intubation and mechanical ventilation in the intensive care unit. He was extubated after 3 days and discharged from hospital 5 days later. At a follow-up outpatient visit 1 and 4 months post-discharge, he had a history of intermittent noisy breathing, which was worse on sleeping and exertion, occasionally associated with signs of increased work of breathing. These symptoms were thought to be sequelae of retained nut fragments. A repeat chest CT scan showed significant improvement, with partial resolution of atelectatic and hyperinflated areas. Three months after his most recent outpatient appointment, he was admitted to hospital with an acute episode of gastroenteritis. During the admission, his parents expressed concern that he had never fully recovered since the foreign body removal. In addition to ongoing respiratory symptoms, he had developed occasional choking episodes, post-prandial vomiting, lethargy and poor weight gain. He was observed to have occasional stridor and episodes of expiratory wheeze, with signs of mild-to-moderate increased work of breathing. The new symptoms, plus persistent respiratory problems, in context of a right-sided aortic arch (detected on previous CT), alerted the attending medical team to the possibility of a vascular ring. A barium swallow study showed vascular impressions from the right-sided aortic arch causing narrowing of the oesophagus, and a significant posterior indentation, suggestive of a vascular ring (Fig. 1). Findings were confirmed on a chest CT angiogram, which showed a right-sided aortic arch with an aberrant left subclavian artery (SCA), originating from a shallow 8 mm-diameter diverticulum of Kommerell. The consequent compression reduced the internal surface area of the trachea from 40 to 17 mm (Fig. 2). A left thoracotomy was performed with division of vascular ring – he was found to have tight mediastinal compression by the ligamentum arteriosum and an atretic left aortic arch, both of which were divided. The Kommerell’s diverticulum was excised and the left SCA re-implanted to the resulting defect. The combined procedures relieved the compression on his trachea and oesophagus. At follow-up 2 months later, he was thriving with minimal residual symptoms.