Innominate artery compression of the trachea: an unusual cause of apnea in a 12-year-old boy.

Abstract: Innominate artery compression of the trachea is a common cause of airway obstruction in infants and young children. The clinical significance of this lesion, even when compression is documented endoscopically or radiographically, is controversial. Obstructive respiratory symptoms occur in only a fraction of such cases, and symptomatic patients are most commonly detected in the first year of life. We present a case of a 12-year-old boy with a chief complaint of progressive stridor and apnea who was diagnosed with symptomatic innominate artery compression of the trachea. We reviewed the literature regarding the pathology, diagnosis, and treatment of this condition.

Key Words: airway obstruction, innominate artery, tracheal compression

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Abnormalities of the great vessels of the mediastinum are estimated to occur in approximately 3% of the general population, and tracheal compression by vascular rings and slings is not uncommon. Although most instances of vascular compression of the trachea are asymptomatic, symptomatic cases are generally diagnosed by 1 year of age. (1) Even when tracheal compression is documented by endoscopy or radiography, controversy exists regarding the clinical significance of such a lesion. This report describes a case of innominate artery compression of the trachea first diagnosed in a patient at 12 years of age and requiring repeat surgery to ameliorate the symptoms.

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)

[FIGURE 1 OMITTED]

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.

[FIGURE 2 OMITTED]

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.

[FIGURE 3 OMITTED]

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.

[FIGURE 4 OMITTED]

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.

Key Points

* Symptomatic innominate artery compression of the trachea most commonly presents in the first 2 years of life.

* In unusual cases, patients may not present with symptoms of airway obstruction until late childhood or adolescence.

* Vascular compression of the trachea may be complicated by tracheomalacia.

* Magnetic resonance imaging is the radiologic procedure of choice in the evaluation of vascular compression syndromes.

From the Department of Radiology, Tulane University Health Sciences Center, New Orleans, LA.

Reprint requests to Harold R. Neitzschman, MD, Department of Radiology, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112-2699. Email: [e-mail]

Accepted February 24, 2003.

Copyright [c] 2003 by The Southern Medical Association

0038-4348/03/9611-1161

References

1. Wiatrak BJ. Congenital anomalies of the larynx and trachea. Otolaryngol Clin North Am 2000;33:91-110.

2. Gross RE, Neuhauser EBD. Compression of the trachea by an anomalous innominate artery: An operation for its relief. Am J Dis Child 1948;75:570-574.

3. Strife JL, Baumel AS, Dunbar JS. Tracheal compression by the innominate artery in infancy and childhood. Radiology 1981;139:73-75.

4. Berdon WE, Baker DH, Bordiuk J, et al. Innominate artery compression of the trachea in infants with stridor and apnea. Radiology 1969;92:272-278.

5. Hawkins JA, Bailey WW, Clark SM. Innominate artery compression of the trachea: Treatment by reimplantation of the innominate artery. J Thorac Cardiovasc Surg 1992;103:678-682.

6. Adler SC, Isaacson G, Balsara RK. Innominate artery compression of the trachea: Diagnosis and treatment by anterior suspension-a 25-year experience. Ann Otol Rhinol Laryngol 1995;104:924-927.

7. Myer CM III, Auringer ST, Wiatrak BJ, et al. Magnetic resonance imaging in the diagnosis of innominate artery compression of the trachea. Arch Otolaryngol Head Neck Surg 1990;116:314-316.

8. Myer CM III, Wiatrak BJ, Cotton RT, et al. Innominate artery compression of the trachea: Current concepts. Laryngoscope 1989;99:1030-1034.

RELATED ARTICLE: Case Report

A 12-year-old black boy, who was a former 24-week gestational age premature infant, with severe spastic cerebral palsy, blindness, and mental retardation, presented to his primary care physician with a chief complaint of stridor and apnea. The patient's mother observed that the patient usually arched his back during his apneic episodes. The patient was referred to an otolaryngologist, who performed an adenoidectomy; however, after endotracheal extubation in the immediate postoperative period, the patient developed severe respiratory distress and was sent to the pediatric intensive care unit. He underwent tracheostomy after a failed extubation attempt a week later. Magnetic resonance imaging of the neck and chest revealed anterior tracheal compression by the innominate artery. A flexible bronchoscopy performed through the tracheostomy tube confirmed anterior compression of the trachea by the innominate artery as well as tracheomalacia. The patient underwent innominate arteriopexy. After a right thoracotomy and posterior retraction of the lung, the pericardium was exposed anteriorly, and a longitudinal incision was made in the pericardium, thereby exposing the distal portion of the ascending aorta. The distal ascending aorta and the base of the innominate artery were further dissected and freed. The junction of the innominate artery and the distal ascending aorta were elevated anteriorly toward the sternum, and relief of tracheal compression was confirmed by bronchoscopy. The aortoinnominate junction was then fixed to the posterior aspect of the manubrium with several simple, interrupted sutures. The suture bites were reinforced with the overlying pericardial sac to avoid tearing of the tracheal vessels. The patient's postoperative course was uncomplicated, and he was discharged to home with plans for future decannulation.

Approximately 7 months later, the patient again presented to his physician with a chief complaint of worsening stridor associated with back arching and apnea. The initial presenting symptoms, although improved after the first surgical intervention, had never completely resolved and the patient was never decannulated. On physical examination, the patient was afebrile, and other vital signs were remarkable for a pulse oximetry of 85% and a respiratory rate of 40 breaths/min. Chest examination revealed suprasternal retractions, stridor, and coarse bilateral breath sounds. The patient was stabilized and underwent magnetic resonance imaging and angiography of the neck and chest, which showed recurrence of the vascular sling (Figs. 1-3). Innominate artery reimplantation to a more proximal region of the aorta was planned, and a median sternotomy incision was performed. The sutures from the previous innominate arteriopexy were observed to be no longer intact. The anterior aspect of the innominate artery segment was dissected and freed, and it was lifted anteriorly while a bronchoscopy was performed. Bronchoscopy during this uplifting maneuver noted only mild relief of the distal tracheomalacia, so a second innominate arteriopexy was performed instead of an innominate artery reimplantation. The innominoaortic segment was secured to the right side of the proximal sternum, and a Gore-Tex patch (W.L. Gore and Associates, Flagstaff, AZ) was used to stiffen the anterior tracheal wall in the region of the distal tracheomalacia.

The patient was weaned off the ventilator without complications and discharged from the hospital breathing humidified room air with good oxygen saturation. At a 1-month follow-up visit, the patient was doing well and no respiratory exacerbations were reported. On physical examination, no purulent respiratory secretions were noted, and the patient assumed a more relaxed posture, without any neck extension or back arching. Bronchoscopy demonstrated diminished collapse of the anterior tracheal wall in the malacic segment. A long, flexible, Bivona cuffless tracheostomy tube was observed to be in place; however, the malacic segment of his trachea was collapsing around the tube, preventing meaningful phonation. Four months after the second innominate arteriopexy, the patient was still being evaluated for a possible downsizing of his tracheostomy tube. A smaller tracheostomy tube may allow him to get an air leak around the tube so that he can be capable of producing speech.

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