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Left pulmonary artery sling: A rare cause of congenital stridor
+Model DIII-820; No. of Pages 3
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Diagnostic and Interventional Imaging (2016) xxx, xxx—xxx
LETTER /Cardiac imaging Left pulmonary artery sling: A rare cause of congenital stridor Keywords Congenital heart disease; Pulmonary artery sling; Ultrasound; CT Dear Editor, Left pulmonary artery sling (LPAS) is a rare vascular abnormality due to failed development of the sixth aortic arch [1,2]. The prevalence is 1 in 17,000 children [3]. We report a case of LPAS initially diagnosed by mediastinal ultrasound and further confirmed by computed tomography (CT). A six-month-old boy was referred to our hospital for congenital stridor, recently aggravated by an episode of bronchiolitis. Regurgitations were also reported since birth. Weight gain was good. The boy had no remarkable prenatal history. Clinical and laryngoscopic examinations revealed no abnormalities. Mediastinal ultrasound disclosed aberrant origin of the left pulmonary artery (Fig. 1). The left pulmonary artery arose from the right pulmonary artery then crossed the midline between the trachea and oesophagus to reach the left pulmonary hilum. Ultrasound also showed a persistent left superior vena cava draining into the coronary sinus. Thoracic aorta and its branches including the origin of coronary arteries were normal. Chest radiograph and upper gastrointestinal series were normal. CT confirmed LPAS (Fig. 2) and persistent left superior vena cava. It
revealed a small diverticulum of the trachea (Fig. 3). The carina was normally at the level of the fifth thoracic vertebra (T5) but the trachea angle bifurcation was increased. The tracheobronchial tree was symmetric suggesting left bronchial isomerism. However, abdominal viscera were normal. Fiberoptic bronchoscopy showed moderate stenosis (10%) but no cartilaginous rings. LPAS can imprint the adjacent structures, causing symptoms, such as stridor, wheezing, recurrent respiratory infections, asthmatic cough, dysphagia or emesis [1—3]. Associated cardiovascular malformation is frequent including anomalies of the aortic arch, patent ductus arteriosus, double outlet right ventricle, ventricular septal defect, atrial septal defect, tetralogy of Fallot, left superior vena cava and partial anomalous pulmonary venous return. Tracheobronchial tree anomalies are common including tracheal bronchus, tracheal diverticulum, tracheal rings, long tracheal stenosis, increased bifurcation angle or bridging bronchus [1,2]. Wells et al. described two types of LPAS depending on the level of the carina: type I with normally located tracheal bifurcation (T4—T5) and type II with low bifurcation (T5—T7) [1]. There are also two subtypes depending on the presence (subtype A) or absence (subtype B) of a tracheal bronchus [1]. A recent CT study found more variability of the level of the carina. An updated classification was proposed based on the tracheobronchial tree, especially the presence of bridging bronchus, rather than on the level of the carina [2]. Type II LPAS is more frequent than type I [4,5]. It appears more frequently associated
Figure 1. a: mediastinum ultrasound using the thymus as acoustic window shows aberrant origin of the left pulmonary artery (white arrow) arising from the right pulmonary artery (star). The left superior vena cava is represented by #, right superior vena cava by circle, aorta by triangle and main pulmonary artery by square; b: color Doppler ultrasound in the transverse plane at the same level shows aberrant origin of the left pulmonary artery.
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012
+Model DIII-820; No. of Pages 3
ARTICLE IN PRESS
2
Letter
Figure 2. a: CT image in the transverse plane after intravenous administration of iodinated contrast material confirms the diagnosis of left pulmonary artery sling (black arrow) arising from the right pulmonary artery (star). Note the right superior vena cava (circle), left superior vena cava (white arrow), aorta (triangle) and main pulmonary artery (square); b: CT image in the transverse plane shows persistent left superior vena cava (short white arrow) and right superior vena cava (long white arrow); c: volume rendered image (view from behind) shows LPAS arising from the right pulmonary artery (white) and crossing behind the trachea (green).
et al. classification, our patient had LPAS type IA considering the normal tracheobronchial pattern. Moreover, tracheal diverticulum is not considered as a tracheal bronchus. The child was operated on and reimplantation of the LPAS into the main pulmonary artery could be performed without tracheoplasty. After surgery, there was a regression of stridor and follow-up was unremarkable. Our case suggests that children with recurrent stridor could be primarily evaluated by mediastinal US to identify LPAS or other abnormal vascular rings. Disclosure of interest The authors declare that they have no competing interest. References Figure 3. MinIP reconstructed image in the coronal plane shows type 1A tracheobronchial tree. White arrow indicates right-sided diverticulum of the trachea. There is no tracheal stenosis. The symmetric aspect of the tracheobronchial tree may suggest a left bronchial isomerism.
with complete cartilaginous rings or long segment stenosis [2,3,5], both anomalies increasing the difficulty of surgery and conditioning the prognosis [4]. Various techniques can be used to diagnose LPAS, including chest radiograph, pulmonary angiography, barium series, bronchoscopy or echocardiography [3]. In our patient, we used mediastinum ultrasound that is not a commonly employed technique to reach this diagnosis. Nevertheless, it is an inexpensive and radiation-free technique. Furthermore, mediastinum is not commonly assessed with echocardiography and could remain a relatively blind zone for the cardiologist. Mediastinum ultrasound remains limited by the size of the thymus window and cooperation of the child. MRI or CT can be used to reveal and confirm cardiovascular or tracheobronchial tree abnormalities. However, low dose CT due to its spatial resolution, short examination time, threedimensional capability including virtual bronchoscopy is an ideal modality for LPAS and specially for diagnosing tracheobronchial tree anomalies [1,4,6]. According to the Wells
[1] Wells TR, Gwinn JL, Landing BH, Stanley P. Reconsideration of the anatomy of sling left pulmonary artery: the association of one form with bridging bronchus and imperforate anus. Anatomic and diagnostic aspects. J Pediatr Surg 1988;23:892—8. [2] Zhong Y-MM, Jaffe RB, Zhu M, Gao W, Sun A-MM, Wang Q. CT assessment of tracheobronchial anomaly in left pulmonary artery sling. Pediatr Radiol 2010;40:1755—62. [3] Yu J-M, Liao C-P, Ge S, Weng Z-C, Hsiung M-C, Chang J-K, et al. The prevalence and clinical impact of pulmonary artery sling on school-aged children: a large-scale screening study. Pediatr Pulmonol 2008;43:656—61. [4] Lee KH, Yoon CS, Choe KO, et al. Use of imaging for assessing anatomical relationships of tracheobronchial anomalies associated with left pulmonary artery sling. Pediatr Radiol 2001;31:269—78. [5] Yong MS, d’Udekem Y, Brizard CP, et al. Surgical management of pulmonary artery sling in children. J Thorac Cardiovasc Surg 2013;145:1033—9. [6] Chassagnon G, Morel B, Carpentier E, Ducou Le Pointe H, Sirinelli D. Tracheobronchial branching abnormalities: lobe-based classification scheme. Radiographics 2016;36:358—73.
D. Delacour a , M. Demeyere a , B. Dubourg a,b , J.-N. Dacher a,b,∗ a Department of Radiology, Unit of Cardiac Imaging, University Hospital of Rouen, 1, rue de Germont, 76031 Rouen, France
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012
+Model DIII-820; No. of Pages 3
ARTICLE IN PRESS
Letter
3 b
Inserm U1096, UFR Médecine Pharmacie, 22, boulevard Gambetta, 76183 Rouen, France
∗ Corresponding
author. Unité imagerie cardiaque, radiologie, CHU de Rouen, 1, rue de Germont, 76031 Rouen cedex, France.
E-mail address: [email protected] (J.-N. Dacher) http://dx.doi.org/10.1016/j.diii.2016.06.012 2211-5684/© 2016 Editions franc ¸aises de radiologie. Published by Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012
ARTICLE IN PRESS
Diagnostic and Interventional Imaging (2016) xxx, xxx—xxx
LETTER /Cardiac imaging Left pulmonary artery sling: A rare cause of congenital stridor Keywords Congenital heart disease; Pulmonary artery sling; Ultrasound; CT Dear Editor, Left pulmonary artery sling (LPAS) is a rare vascular abnormality due to failed development of the sixth aortic arch [1,2]. The prevalence is 1 in 17,000 children [3]. We report a case of LPAS initially diagnosed by mediastinal ultrasound and further confirmed by computed tomography (CT). A six-month-old boy was referred to our hospital for congenital stridor, recently aggravated by an episode of bronchiolitis. Regurgitations were also reported since birth. Weight gain was good. The boy had no remarkable prenatal history. Clinical and laryngoscopic examinations revealed no abnormalities. Mediastinal ultrasound disclosed aberrant origin of the left pulmonary artery (Fig. 1). The left pulmonary artery arose from the right pulmonary artery then crossed the midline between the trachea and oesophagus to reach the left pulmonary hilum. Ultrasound also showed a persistent left superior vena cava draining into the coronary sinus. Thoracic aorta and its branches including the origin of coronary arteries were normal. Chest radiograph and upper gastrointestinal series were normal. CT confirmed LPAS (Fig. 2) and persistent left superior vena cava. It
revealed a small diverticulum of the trachea (Fig. 3). The carina was normally at the level of the fifth thoracic vertebra (T5) but the trachea angle bifurcation was increased. The tracheobronchial tree was symmetric suggesting left bronchial isomerism. However, abdominal viscera were normal. Fiberoptic bronchoscopy showed moderate stenosis (10%) but no cartilaginous rings. LPAS can imprint the adjacent structures, causing symptoms, such as stridor, wheezing, recurrent respiratory infections, asthmatic cough, dysphagia or emesis [1—3]. Associated cardiovascular malformation is frequent including anomalies of the aortic arch, patent ductus arteriosus, double outlet right ventricle, ventricular septal defect, atrial septal defect, tetralogy of Fallot, left superior vena cava and partial anomalous pulmonary venous return. Tracheobronchial tree anomalies are common including tracheal bronchus, tracheal diverticulum, tracheal rings, long tracheal stenosis, increased bifurcation angle or bridging bronchus [1,2]. Wells et al. described two types of LPAS depending on the level of the carina: type I with normally located tracheal bifurcation (T4—T5) and type II with low bifurcation (T5—T7) [1]. There are also two subtypes depending on the presence (subtype A) or absence (subtype B) of a tracheal bronchus [1]. A recent CT study found more variability of the level of the carina. An updated classification was proposed based on the tracheobronchial tree, especially the presence of bridging bronchus, rather than on the level of the carina [2]. Type II LPAS is more frequent than type I [4,5]. It appears more frequently associated
Figure 1. a: mediastinum ultrasound using the thymus as acoustic window shows aberrant origin of the left pulmonary artery (white arrow) arising from the right pulmonary artery (star). The left superior vena cava is represented by #, right superior vena cava by circle, aorta by triangle and main pulmonary artery by square; b: color Doppler ultrasound in the transverse plane at the same level shows aberrant origin of the left pulmonary artery.
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012
+Model DIII-820; No. of Pages 3
ARTICLE IN PRESS
2
Letter
Figure 2. a: CT image in the transverse plane after intravenous administration of iodinated contrast material confirms the diagnosis of left pulmonary artery sling (black arrow) arising from the right pulmonary artery (star). Note the right superior vena cava (circle), left superior vena cava (white arrow), aorta (triangle) and main pulmonary artery (square); b: CT image in the transverse plane shows persistent left superior vena cava (short white arrow) and right superior vena cava (long white arrow); c: volume rendered image (view from behind) shows LPAS arising from the right pulmonary artery (white) and crossing behind the trachea (green).
et al. classification, our patient had LPAS type IA considering the normal tracheobronchial pattern. Moreover, tracheal diverticulum is not considered as a tracheal bronchus. The child was operated on and reimplantation of the LPAS into the main pulmonary artery could be performed without tracheoplasty. After surgery, there was a regression of stridor and follow-up was unremarkable. Our case suggests that children with recurrent stridor could be primarily evaluated by mediastinal US to identify LPAS or other abnormal vascular rings. Disclosure of interest The authors declare that they have no competing interest. References Figure 3. MinIP reconstructed image in the coronal plane shows type 1A tracheobronchial tree. White arrow indicates right-sided diverticulum of the trachea. There is no tracheal stenosis. The symmetric aspect of the tracheobronchial tree may suggest a left bronchial isomerism.
with complete cartilaginous rings or long segment stenosis [2,3,5], both anomalies increasing the difficulty of surgery and conditioning the prognosis [4]. Various techniques can be used to diagnose LPAS, including chest radiograph, pulmonary angiography, barium series, bronchoscopy or echocardiography [3]. In our patient, we used mediastinum ultrasound that is not a commonly employed technique to reach this diagnosis. Nevertheless, it is an inexpensive and radiation-free technique. Furthermore, mediastinum is not commonly assessed with echocardiography and could remain a relatively blind zone for the cardiologist. Mediastinum ultrasound remains limited by the size of the thymus window and cooperation of the child. MRI or CT can be used to reveal and confirm cardiovascular or tracheobronchial tree abnormalities. However, low dose CT due to its spatial resolution, short examination time, threedimensional capability including virtual bronchoscopy is an ideal modality for LPAS and specially for diagnosing tracheobronchial tree anomalies [1,4,6]. According to the Wells
[1] Wells TR, Gwinn JL, Landing BH, Stanley P. Reconsideration of the anatomy of sling left pulmonary artery: the association of one form with bridging bronchus and imperforate anus. Anatomic and diagnostic aspects. J Pediatr Surg 1988;23:892—8. [2] Zhong Y-MM, Jaffe RB, Zhu M, Gao W, Sun A-MM, Wang Q. CT assessment of tracheobronchial anomaly in left pulmonary artery sling. Pediatr Radiol 2010;40:1755—62. [3] Yu J-M, Liao C-P, Ge S, Weng Z-C, Hsiung M-C, Chang J-K, et al. The prevalence and clinical impact of pulmonary artery sling on school-aged children: a large-scale screening study. Pediatr Pulmonol 2008;43:656—61. [4] Lee KH, Yoon CS, Choe KO, et al. Use of imaging for assessing anatomical relationships of tracheobronchial anomalies associated with left pulmonary artery sling. Pediatr Radiol 2001;31:269—78. [5] Yong MS, d’Udekem Y, Brizard CP, et al. Surgical management of pulmonary artery sling in children. J Thorac Cardiovasc Surg 2013;145:1033—9. [6] Chassagnon G, Morel B, Carpentier E, Ducou Le Pointe H, Sirinelli D. Tracheobronchial branching abnormalities: lobe-based classification scheme. Radiographics 2016;36:358—73.
D. Delacour a , M. Demeyere a , B. Dubourg a,b , J.-N. Dacher a,b,∗ a Department of Radiology, Unit of Cardiac Imaging, University Hospital of Rouen, 1, rue de Germont, 76031 Rouen, France
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012
+Model DIII-820; No. of Pages 3
ARTICLE IN PRESS
Letter
3 b
Inserm U1096, UFR Médecine Pharmacie, 22, boulevard Gambetta, 76183 Rouen, France
∗ Corresponding
author. Unité imagerie cardiaque, radiologie, CHU de Rouen, 1, rue de Germont, 76031 Rouen cedex, France.
E-mail address: [email protected] (J.-N. Dacher) http://dx.doi.org/10.1016/j.diii.2016.06.012 2211-5684/© 2016 Editions franc ¸aises de radiologie. Published by Elsevier Masson SAS. All rights reserved.
Please cite this article in press as: Delacour D, et al. Left pulmonary artery sling: A rare cause of congenital stridor. Diagnostic and Interventional Imaging (2016), http://dx.doi.org/10.1016/j.diii.2016.06.012