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Pulmonary Artery Sling: A Rare Cause of Tracheomalacia in the Adult

Odell, David D. MD*,†; Gangadharan, Sidhu P. MD*; Majid, Adnan MD, FCCP

Journal of Bronchology & Interventional Pulmonology: July 2011 - Volume 18 - Issue 3 - p 278–280
doi: 10.1097/LBR.0b013e318228f45b
Case Reports
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Tracheomalacia (TM) is an under-recognized condition that presents with nonspecific symptoms such as dyspnea, cough, and recurrent infections. Frequently, patients with this condition are misdiagnosed with more prevalent diseases such as asthma and chronic obstructive pulmonary disease. We report a case of a 29-year-old woman with long-standing, mild, persistent asthma characterized by dyspnea and cough, who experienced acute and severe worsening of her symptoms after the cesarean section for the delivery of her third child. She was initially treated with bronchodilators and oral corticosteroids without improvement. She underwent further evaluation with a chest computed tomographic scan and a flexible bronchoscopy, which revealed focal TM in the distal trachea secondary to chronic extrinsic compression due to a pulmonary vascular sling. We discuss her subsequent evaluation and management.

*Division of Thoracic Surgery

Harvard/MIT Health Sciences and Technology, in collaboration with Pfizer Inc. and Merck & Co

Division of Interventional Pulmonology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA

Author Involvement: Conception, hypothesis generation, and study design by D.D.O., S.P.G., and A.M. Data acquisition, analysis, and interpretation by D.D.O., S.P.G., and A.M. Article preparation and submission by D.D.O., S.P.G., and A.M.

Disclosure: The authors have no conflicts of interest to report.

Reprints: Adnan Majid, MD, FCCP, 185 Pilgrim Road, Suite # Deaconess 201, Boston, MA, 02215 (e-mail: amajid@bidmc.harvard.edu).

Received May 23, 2011

Accepted June 13, 2011

Pulmonary artery (PA) sling is an uncommon form of vascular ring, which results from an aberrant division of the main PA. PA slings may produce a combination of symptoms related to focal compression of the airway or esophagus with diagnosis of the condition typically made in childhood. Rarely, adult presentations with symptoms of dysphagia have been reported. We present a case of PA sling in the adult resulting in focal tracheomalacia and significant respiratory symptoms.

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CASE REPORT

A 29-year-old woman experienced acute onset of severe dyspnea, intractable “barking” cough, and wheezing after the cesarean section delivery of her third child. She had a history of seasonal pollen allergies and quiescent asthma, diagnosed in childhood and treated with inhaled steroids, and a life-long pattern of exertional dyspnea attributed to the same. She had a 20 pack-year smoking history, but was a nonsmoker for 10 years. She denied recent travel or other exposures and had no similar problems after the birth of her first 2 children, also by cesarean section.

The patient was treated with bronchodilators and oral corticosteroids without improvement. Chest radiography revealed no specific abnormality, and subsequent bronchoscopy with bronchoalveolar lavage was positive for Klebsiella pneumoniae (>10,000 colonies). Despite an appropriate antiinfective regimen, she had persistent cough and exertional dyspnea, limiting activity. IgE levels were normal and Aspergillus-specific antigens ANCA and CRP were all negative, arguing against vasculitis or allergic etiology. Pulmonary function testing demonstrated a mild restrictive pattern. Chest computed tomographic scan without contrast showed narrowing of the distal trachea pertaining to focal malacia and the patient was referred to our institution for further evaluation.

Following a standard protocol for the evaluation of tracheobronchomalacia, she underwent a dynamic airway computed tomography with images acquired during both inspiration and expiration. This study identified a PA sling, resulting in extrinsic compression and collapse of the membranous wall of the distal trachea and proximal left mainstem bronchus (Fig. 1). Dynamic flexible bronchoscopy revealed a pulsatile extraluminal mass causing extrinsic airway compression, without complete tracheal rings or areas of fixed stenosis (Fig. 2). A magnetic resonance angiography study was carried out to further delineate the vascular anatomy (Fig. 3). The anomalous left PA originated from the proximal right PA, passing between the trachea and esophagus and compressing the distal trachea. Surgical resection of the vascular sling was accomplished with reanastomosis to the main PA through median sternotomy on cardiopulmonary bypass. No airway reconstruction was required. She recovered well, with complete resolution of respiratory symptoms.

FIGURE 1

FIGURE 1

FIGURE 2

FIGURE 2

FIGURE 3

FIGURE 3

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DISCUSSION

Vascular rings are unusual congenital anomalies that occur early in the development of the aortic arch and great vessels. Symptoms associated with vascular rings relate to the structures that are encircled by the ring, mainly the trachea and esophagus. These anomalies are uncommon, accounting for <1% of congenital cardiac defects. The 2 most common forms are the double aortic arch and the right aortic arch with a left ligamentum arteriosum, accounting for 85% of cases.1–3 The anomalous left PA, or PA sling, accounts for approximately 10% of cases.

PA sling was first described at autopsy by Laevecke in 1897.4 Symptoms range from absent-to-severe respiratory distress, with airway symptoms predominating in infants, whereas dysphagia may be the primary complaint of older patients.5 The anomaly is created by formation of the left PA from the right sixth vascular arch (rather than the left), resulting in a left PA arising from the posterior aspect of the right PA. A strong embryologic association exists between PA slings and development of complete tracheal rings, accentuating tracheal stenosis.6

Surgical repair is focused on restoration of the normal anatomic relationship between the airway and pulmonary vasculature. Exposure is obtained by median sternotomy, typically under cardiopulmonary bypass.7 The left PA is disconnected from the right PA trunk and anastomosed to the proximal main PA. Careful examination of the trachea is required as >50% of patients have associated severe tracheobronchial anomalies such as tracheomalacia, stenosis, webs, or complete tracheal rings. In the presence of complete tracheal rings and concomitant tracheal stenosis, segmental resection and reconstruction by slide tracheoplasty are often necessitated.5 Routine preoperative transthoracic echocardiography is recommended to exclude associated congenital heart defects, which are present in approximately 10% to 15% of the cases.5

Adult presentation of PA sling is rare, with only 22 reported in the literature. Of these, only 1 patient required surgical correction for symptoms of dysphagia.8 This is the first report of the need for surgical correction of a PA sling in adulthood due to respiratory symptoms. Interestingly, the sharp anterior angulation of the anomalous left PA resulted in compression of the distal trachea and proximal left mainstem bronchus in our patient, rather than the typical right-sided compression, although it is unclear whether this conformation affected the severity of respiratory symptoms. Although rarely required, this case demonstrates that isolated surgical correction of PA sling in an adult can ameliorate respiratory symptoms secondary to focal tracheomalacia, even without airway reconstruction.

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REFERENCES

1. Humphrey C, Duncan K, Fletcher S. Decade of experience with vascular rings at a single institution. Pediatrics. 2006;117:e903–e908
2. Greiner A, Perkmann R, Rieger M, et al. Vascular ring causing tracheal compression in an adult patient. Ann Thorac Surg. 2003;75:1959–1960
3. Grathwohl KW, Afifi AY, Dillard TA, et al. Vascular rings of the thoracic aorta in adults. Am Surg. 1999;65:1077–1083
4. Laevecke HD,H. Uber cine seltene angborene Anomalie der Pulomonalarterie. Munch Med Wochenschr. 1897;44:950–951
5. Fiore AC, Brown JW, Weber TR, et al. Surgical treatment of pulmonary artery sling and tracheal stenosis. Ann Thorac Surg. 2005;79:38–46 discussion 38–46
6. Sade RM, Rosenthal A, Fellows K, et al. Pulmonary artery sling. J Thorac Cardiovasc Surg. 1975;69:333–346
7. Backer CL, Mavroudis C, Dunham ME, et al. Pulmonary artery sling: results with median sternotomy, cardiopulmonary bypass, and reimplantation. Ann Thorac Surg. 1999;67:1738–1744 discussion 1744–1735
8. LaBelle MF, Rainer WG, Ratzer E, et al. Surgical repair of pulmonary artery sling in an adult. Ann Thorac Surg. 90:1009–1011.
9. Murgu S, Colt H. Tracheomalacia and excessive dynamic airway collapse. Respirology. 2006;11:38–406
    10. Carden K, Boiselle P, Waltz DA, et al. Tracheomalacia and Tracheobronchomalcia in children and adults: an in depth review. Chest. 2005;127:984–1005
    Keywords:

    trachea; tracheomalacia; pulmonary artery; congenital vascular anomaly; vascular ring; airway obstruction

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