INTRODUCTION: Double aortic arch (DAA) is the most common clinically recognized form of vascular ring, in which the trachea and esophagus are encircled by the aortic arch and its branches. The overall incidence is unknown. Half to two-thirds of patients undergoing vascular ring repair have a DAA; of these 42% have respiratory symptoms, one third have dysphagia and one third are asymptomatic. Surgical division of the arch (usually on the left) is associated with prompt relief of symptoms.
CASE PRESENTATION: A 14 year old girl presented with a history of intermittent cough only in the winter daytime since 2 months of age, and peanut allergy. In January 2008 she received intravenous steroids and epinephrine for presumed anaphylaxis associated with airway obstruction. She was prescribed inhaled bronchodilators, without benefit. She has had no problems with dysphagia and had a negative review of systems. On physical examination, she appeared well nourished, in no acute distress with normal vital signs and the rest of her physical examination was also normal. Spirometric findings were typical of a fixed intrathoracic airway obstruction. The chest radiograph showed characteristic narrowing in the intrathoracic trachea and air trapping. Echocardiogram revealed normal intracardiac anatomy. A contrast-enhanced computed tomography (CT) scan complemented by three dimensional CT reconstruction revealed DAA with a dominant right sided arch and tracheal narrowing in the mid thoracic trachea.
DISCUSSIONS: In DAA, the ascending aorta divides into left (anterior) and right (posterior) arches passing to either side of the trachea, the right arch being dominant in 70 % of cases. Associated cardiovascular anomalies are uncommon, but when present are usually cyanotic, including tetralogy of Fallot and transposition of great arteries. Usually diagnosed in infancy or early childhood, DAA commonly manifests with symptoms of stridor, dyspnea, cough and recurrent respiratory infections. Patients may experience dysphagia related to esophageal compression, which may manifest as vomiting and feeding intolerance. The diagnosis is suggested on the plain chest radiograph and barium swallow, and confirmed by CT or MRI scanning, which clearly demonstrate the arterial branching pattern and the location and extent of airway and esophageal obstruction. A 3-dimensional reconstruction of the aorta and airways can be a useful tool for preoperative planning. Echocardiography may be helpful in the evaluation of associated cardiovascular anomalies. The long-term prognosis for patients with repaired DAA is quite good. Persistent respiratory symptoms are the most common adverse outcomes. Pulmonary function testing reveals persistent upper airway obstruction in some patients. In one case series report, surgical relief of asymptomatic vascular rings was advocated in children to reduce the risk of tracheomalacia in adult life.
CONCLUSION: In summary, DAA is an important cause of persistent respiratory symptoms in infants, children or in adults. Early diagnosis and timely intervention can minimize airway complications. Further investigations including chest radiography, pulmonary function test and other imaging techniques are warranted.
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