Ann Thorac Surg 1995;59:526-528
© 1995 The Society of Thoracic Surgeons
Case Reports
Innominate Artery and Tracheal Compression Due to Aberrant Position of the Thymus
Mark H. Hennington, MD,
Frank C. Detterbeck, MD,
Paul L. Molina, MD,
Robert E. Wood, MD
Departments of Surgery, Radiology, and Pediatrics, University of North Carolina School of Medicine, Chapel Hill, North Carolina
Accepted for publication June 8, 1994.
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Abstract
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A 3-month-old infant with failure to thrive was found on bronchoscopy to have tracheal obstruction thought to be secondary to innominate artery compression. Subsequent diagnostic evaluation with magnetic resonance imaging revealed superior and posterior extension of the thymus with resultant compression of the innominate artery and trachea within the narrow confines of the thoracic inlet. Resection of the aberrantly positioned and enlarged thymus and aortopexy resulted in relief of tracheal compression.
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Introduction
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Tracheal compression by the innominate artery may result from an aberrant origin of the artery from the proximal thoracic aorta. Less commonly, the innominate artery is displaced by an anterior mediastinal mass and thus causes compression of the trachea. We report such a case in an infant with innominate artery displacement from an aberrantly positioned thymus, resulting in symptomatic tracheal compression.
A 3-month-old female infant was referred to the pediatric pulmonary service for persistent inspiratory stridor. The infant manifested failure-to-thrive and was below the fifth percentile on growth curves. No evidence of gastroesophageal reflux or reactive airway disease was seen. A chest radiogram (Fig 1A
) was remarkable for a narrowed cervicothoracic tracheal air shadow. Fiberoptic bronchoscopy revealed marked extrinsic compression of the trachea (Fig 1B) with normal distal airways. The abnormality was thought to be the result of innominate artery compression; however, magnetic resonance imaging examination revealed an abnormally positioned right thymic lobe that had encroached superiorly and laterally into the cervicothoracic inlet (Fig 2). The thymic lobe appeared to displace the innominate artery in the area of the thoracic inlet, with resultant tracheal obstruction. Because of the child's marked dyspnea and growth retardation, thymectomy and innominate artery suspension were undertaken.
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Fig 1. . (A) Preoperative lateral chest radiogram showing marked tracheal narrowing (arrow). (B) Tracheobronchoscopy showing extrinsic compression of the trachea.
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Fig 2. . (A) Coronal T1-weighted (TR = 457 ms, TE = 25 ms) magnetic resonance image shows cervical extension of the enlarged right thymic lobe and resultant compression of the innominate artery (curved arrow) and trachea (straight arrow). (B) Corresponding transaxial T1-weighted (TR = 488 ms, TE = 25 ms) magnetic resonance image again demonstrates tracheal compression (asterisk). (A = innominate artery; TH = thymus; V = innominate vein.)
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Exploration through a right posterolateral thoracotomy revealed that the left thymic lobe was positioned slightly to the right of midline. The right lobe of the thymus was protruding posterior to the superior vena cava (Fig 3). This lobe extended into the thoracic inlet over the innominate vein and then joined the left thymic lobe. This caused direct impingement and posterior displacement of the innominate artery. Decompression of the thoracic inlet was achieved by removal of the right thymic lobe, which was found to be histologically normal. The innominate artery was suspended to the anterior chest wall to alleviate any residual tracheal compression. Postoperative chest radiogram revealed complete resolution of the tracheal compression (Fig 4). The patient recovered uneventfully, has gained weight normally, and is asymptomatic.
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Fig 3. . Operative view through right thoracotomy showing the relationship of the herniated right lobe of thymus (large closed arrow) to the superior vena cava (open arrow) and phrenic nerve (small closed arrow).
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Comment
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Endoscopic or radiographic evidence of tracheal compression may occasionally be seen in the asymptomatic child [1, 2], but it may cause severe symptoms, such as apneic episodes, recurrent pneumonias, or stridor, and require surgical intervention [3–5]. Tracheal compression may be caused by mediastinal masses, such as cystic hygromas, hemangiomas, teratomas, and thymic cysts [6], but the cause of such compression is most commonly an aberrant origin of the innominate artery from the aortic arch. Mediastinal masses may also cause tracheal compression indirectly by displacing the innominate artery. In such cases, resection of the mass lesion is the primary intervention, although the additional maneuver of innominate artery suspension or reimplantation may be necessary [7, 8].
The thymus as a cause of tracheal compression has been described previously [9]. In its normal position, the thymus does not cause tracheal obstruction, despite its being enlarged in the infant. However, if the thymus protrudes into the relatively narrow thoracic inlet, compression of surrounding structures may occur. In this case, displacement of the innominate artery by an aberrantly positioned and enlarged thymic lobe led to tracheal compression.
Tracheobronchoscopy is indicated to evaluate the airway in the infant with airway compromise. This case demonstrates the value of additional imaging modalities. Magnetic resonance imaging has become the study of choice because it avoids the use of ionizing radiation or intravenous contrast medium and allows imaging in coronal and sagittal planes [10, 11].
A case of tracheal compression is presented. Magnetic resonance imaging was instrumental in demonstrating malposition of the right thymic lobe into the thoracic inlet, which caused innominate artery displacement and tracheal compression. Successful treatment consisted of removal of the abnormally positioned thymic lobe and suspension of the innominate artery.
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Footnotes
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Address reprint requests to Dr Detterbeck, University of North Carolina, CB 7065, 108 Burnett-Womack Building, Chapel Hill, NC 27599-7065.
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References
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- Welz A, Reichert B, Weinhold C, et al. Innominate artery compression of the trachea in infancy and childhood: is surgical therapy justified? Thorac Cardiovasc Surg 1984;32:85–8.[Medline]
- Strife JL, Baumel AS, Dunbar JS. Tracheal compression by the innominate artery in infancy and children. Radiology 1981;139:73–5.[Abstract/Free Full Text]
- Fletcher BD, Cohn RC. Tracheal compression by congenital cardio-vascular anomalies in children. Ann Otolaryngol 1963;72:949–69.
- MacDonald RE, Fearon B. Innominate artery compression syndrome in children. Ann Otolaryngol 1971;80:535–40.
- Parsons D, Cotton R, Crysdale W. Distal tracheal compression. Head Neck 1991;13:251–4.[Medline]
- Hawkins JA, Bailey WW, Clark SM. Innominate artery compression of the trachea: treatment by reimplantation of the innominate artery. J Thorac Cardiovasc Surg 1992;103:678–82.[Abstract]
- Moes CAF, Izukawa T, Trusler GA. Innominate artery compression of the trachea. Bull N Y Acad Med 1984;60:525–31.[Medline]
- Mandell GA, McNicholas KW, Harcke HT. Innominate artery compression of the trachea: Relationship to the cervical herniation of normal thymus. Radiology 1994;190:131–5.[Abstract/Free Full Text]
- Hofman U, Hofman D, Vogl T, Wilimzig C, Mantel K. Magnetic resonance imaging as a new diagnostic criterion in pediatric airway obstruction. Progr Pediatr Surg 1991;27: 221–30.
- Vogl T, Wilimzig C, Hofmann U, Hofmann D, Dresel S, Lissner J. MRI in tracheal stenosis by innominate artery in children. Pediatr Radiol 1991;21:89–93.[Medline]
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Abstract
Introduction
