Innominate Artery Compression of the Trachea: An Unusual Cause of Apnea in a 12-Year-Old Boy

Elliott Friedman, BA; Alana Kennedy, MD; Harold R. Neitzschman, MD

Disclosures

South Med J. 2003;96(11) 

In This Article

Discussion

Anomalies of the great vessels of the mediastinum are not uncommon, but only a small fraction of cases involving vascular compression of the airway cause obstructive symptomatology. Innominate artery compression of the trachea represents the most common cause of airway compression by a vascular sling. Symptomatic patients typically present with expiratory stridor, cough, recurrent bronchopulmonary infections, and occasionally apnea.[1]

The syndrome of innominate artery compression of the trachea as first reported by Gross and Neuhauser[2] in 1948 was originally thought to be attributable to an aberrant innominate artery that originated anomalously on the left side of the aortic arch and coursed obliquely from left to right causing an anterior indentation of the trachea (Fig. 4). In 1981, Strife et al[3] reviewed approximately 172 anteroposterior aortograms and angiocardiograms and 1,000 lateral radiographs from infants, children, and adolescents. They found that the innominate artery originated at least partially to the left of the trachea in approximately 95% of cases, suggesting that this location of origin is actually normal in children. Tracheal indentation, most often of mild severity, was seen in 30% of patients younger than 2 years of age, with an increased incidence of indentation noted in children with congenital heart disease. In both groups of patients, tracheal indentation was found to be age-related; the syndrome is rarely seen in children older than 1.5 years of age.

Schematic diagram demonstrating the innominate artery arising from the arch of the aorta to the left of the midline, and crossing anterior to the trachea.

The vast majority of patients with anterior tracheal compression fail to exhibit symptoms associated with respiratory compromise. There is no consensus as to why some patients are more prone to symptomatic innominate artery compression of the trachea; however, Berdon et al[4] suggested that innominate artery syndrome is more likely to arise in patients with a "crowded" superior mediastinum, such as in those patients with congenital heart disease.[3] Tracheomalacia may be an important factor in some instances of tracheal obstruction secondary to vascular causes.

By 3 years of age, growth of the aortic arch causes the innominate artery to move cephalad, to the right, and anteriorly, away from the trachea.[5] Other factors, including continued growth of supportive tracheal cartilage, thymic involution, and rib cage growth may also be partially responsible for the decreased incidence of tracheal compression with advancing age.[5,6] In the presented case, the patient's persistent symptomatic trachea compression is likely caused by severe tracheomalacia and failure of the innominate artery to move away from the trachea as development progressed.

Diagnosis of innominate artery compression of the trachea in patients presenting with symptoms of airway obstruction can be presumed with chest radiographs and bronchoscopy, which often shows a pulsatile anterior compression of the trachea a few centimeters above the carina.[6] Magnetic resonance imaging (MRI) is the radiologic procedure of choice for evaluating compressive lesions of the trachea in children. MRI is an appropriate imaging modality in children because it is nonionizing, noninvasive, and does not require IV contrast. In addition, MRI effectively demonstrates the anatomy of vascular rings and slings before surgery. In the sagittal plane, MRI will show the innominate artery originating just anterior to the compressed section of the trachea, and it is the most useful image for demonstrating the level of anteroposterior tracheal compression. Coronal images will show the innominate artery crossing the trachea from left to right. Axial sections demonstrate the proximity of the artery to the trachea and provide the best approximation of tracheal narrowing.[7] Flow-volume loops obtained before and after exercise provide a reliable estimation of the degree of airway compression caused by this syndrome. Although most symptomatic cases of innominate artery compression of the trachea are diagnosed in the first few years of life, delayed onset of symptoms has been reported in adolescents.[8]

The majority of patients with innominate artery compression of the trachea are successfully treated with medical management, which generally includes humidified oxygen, steroids, and antibiotics, as required. Surgery is indicated for patients with apnea, multiple episodes of tracheobronchitis or bronchopneumonia, and after 48 hours of failing to respond to medical therapy. Airway compression in children with intrinsic airway disease such as tracheomalacia or asthma, as well as exercise intolerance may be considered relative indications for surgery. Endoscopic evidence of tracheal compression in an asymptomatic patient is not considered an indication for surgery.[8] Arteriopexy, entailing anterior suspension of the innominate artery to the sternum,[6] and reimplantation of the innominate artery to a more proximal site on the ascending aorta[5] are the most commonly used methods of surgical repair for relief of symptoms. No clear consensus exists as to which procedure is preferable.

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