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A 55-Year-Old Man With a Small Right Lung and a Right-Sided HeartSmall Right Lung and a Right-Sided Heart FREE TO VIEW

Jeffrey Albores, MD; Joanne Bando, MD; M. Iain Smith, MD
Author and Funding Information

From the Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA.

CORRESPONDENCE TO: Jeffrey Albores, MD, Division of Pulmonary and Critical Care Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, Room 37-131 CHS, Los Angeles, CA 90095-1690; e-mail: jalbores@mednet.ucla.edu


Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;147(3):e95-e99. doi:10.1378/chest.14-1054
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A healthy 55-year-old man without known medical problems presented for a routine physical examination and was found to have an abnormal ECG. He denied chest pain, dyspnea, palpitations, dizziness, or syncopal episodes. He also denied orthopnea, paroxysmal nocturnal dyspnea, and lower-extremity edema. His exercise capacity had been excellent. He was a lifelong nonsmoker and never had lung problems.

Figures in this Article

The patient’s vital signs were as follows: BP, 120/90 mm Hg; pulse, 70 beats/min; respiration, 18 breaths/min; and oxygen saturation as measured by pulse oximetry, 98% on ambient air. Cardiac examination revealed a point of maximal impulse 1 cm to the right of the lower sternal border, normal heart sounds, no murmurs, and no jugular venous distension. Lung examination was pertinent for decreased breath sounds on the right side of his chest. There was no cyanosis or edema in his extremities.

The ECG demonstrated a normal sinus rhythm with right axis deviation. A chest radiograph is shown in Figure 1. An echocardiogram showed normal biventricular size and function without evidence of pulmonary hypertension or septal defect. A chest CT scan is shown in Figure 2.

Figure Jump LinkFigure 1 –  The initial chest radiograph.Grahic Jump Location
Figure Jump LinkFigure 2 –  A-I, Serial transverse cuts of high resolution chest CT scan with contrast.Grahic Jump Location
What is the likely diagnosis?
What study would help establish the diagnosis?
Diagnosis: Scimitar (hypogenetic lung) syndrome confirmed by cardiovascular magnetic resonance with magnetic resonance angiogram

Scimitar (hypogenetic lung) syndrome is a rare congenital anomaly from a combined vascular and bronchopulmonary (lung bud) malformation. Scimitar syndrome is characterized by partial anomalous pulmonary venous connection (PAPVC) and predominantly right-sided hypoplastic lung with ipsilateral hypoplastic pulmonary artery. PAPVC refers to a specific group of congenital cardiac anomalies caused by an abnormal return of one or more, but not all, of the pulmonary veins to the right side of the heart instead of draining into the left atrium. In scimitar syndrome, the anomalous pulmonary (scimitar) vein usually drains to the inferior vena cava (IVC), often giving the appearance of a curved scimitar sword on chest radiograph. The scimitar vein can also drain into the right atrium, superior vena cava, azygous vein, or other intermediary venous connections. Coexisting cardiac anomalies, such as dextrocardia, atrial septal defect, pulmonary vein stenosis, coarctation of the aorta, ventricular septal defect, and patent ductus arteriosus are commonly associated with this syndrome.

Scimitar syndrome comprises about 3% to 6% of all PAPVCs, which in turn have an estimated prevalence of 0.7% of the population. However, the true prevalence of scimitar syndrome is unknown because this syndrome may be undetected in asymptomatic adults who have not undergone chest radiograph. The pathogenesis of scimitar syndrome relates to a combined aberrant intrauterine development of embryonic angiogenesis (PAPVC) and lung bud embryogenesis (lung hypoplasia).

Scimitar syndrome has varied clinical manifestations depending on age of presentation. Scimitar syndrome presents more commonly during infancy and follows a more symptomatic course with a poorer prognosis compared with its presentation during childhood or adulthood. Most affected infants have pulmonary hypertension and heart failure at the time of diagnosis. On the other end of the spectrum, adults identified with this syndrome are usually asymptomatic, being diagnosed incidentally or with the evaluation of nondisabling or subtle symptoms. If symptomatic, presentation at adulthood includes dyspnea and fatigue. Hemoptysis and pulmonary arterial hypertension are uncommon presentations in adult life. Chest infections may occur and are usually confined to the right-side hypoplastic lung because hypoplastic lungs may have impaired airway clearance similar to pulmonary sequestration.

Diagnosis of scimitar syndrome relies on imaging studies. Chest radiograph findings may show a hypoplastic right lung; dextroposition of the heart; and in one-third of cases, the characteristic curved scimitar sword appearance due to coursing of the scimitar vein inferiorly toward the IVC. Diagnostic workup starts with echocardiography to rule out congenital cardiac anomalies and to screen for pulmonary hypertension. Chest CT scan with three-dimensional reconstruction views confirms the diagnosis of scimitar syndrome because it provides more detailed anatomic information than echocardiography and enhanced visualization of the hypoplastic lung and the pulmonary vasculature if contrast is administered. Cardiovascular magnetic resonance (CMR), an MRI scan of the heart and blood vessels, also confirms the diagnosis of scimitar syndrome. Compared with chest CT scan, CMR can further characterize congenital heart disease as well as provide quantitation of heart chamber volumes, ventricular mass, and blood flow through the great vessels. As an adjunct to CMR, magnetic resonance angiography (MRA) provides enhanced visualization of the pulmonary vasculature, including the anomalous pulmonary vein. MRA phase velocity mapping allows noninvasive determination of pulmonary vein blood flow and pulmonary-to-systemic flow ratio. The pulmonary-to-systemic flow ratio increases with the degree of left-to-right shunting in patients with PAPVC. Cardiac catheterization is rarely performed for diagnostic purposes because of the availability of other less invasive diagnostic modalities (echocardiography, CT scan, and MRI). Cardiac catheterization is usually reserved for patients with symptoms and pulmonary hypertension found on echocardiography to provide hemodynamic information, such as pulmonary vascular resistance, cardiac output, and ventricular pressures.

Most asymptomatic adults with scimitar syndrome will continue without symptoms and not require treatment, and there are no guidelines about monitoring these individuals. Definitive surgical management is indicated in the presence of pulmonary hypertension with right-sided heart failure, hemodynamically significant left-to-right shunt, recurrent pulmonary infections, or compressive effects on surrounding structures (ie, tracheobronchial tree) by the anomalous vein. Available surgical interventions include resection of anomalously drained infected lung or reimplantation of the scimitar vein into the left atrium.

Clinical Course

Following the initial incidental chest radiograph finding, the patient was given a diagnosis of scimitar syndrome after chest CT scan with contrast, CMR, and MRA. The initial chest radiograph (Fig 1) showed dextroposition of the heart and major vessels with right-sided volume loss and signs of anomalous pulmonary veins, which were not classic in appearance for scimitar syndrome. In Figure 2, chest CT scan demonstrated dextrocardia, a hypoplastic right-side lung, hypoplastic right-side main pulmonary artery (Fig 2C), and bronchial aplasia and hypoplasia. The right lower lobe had both pulmonary and systemic arterial supply. The right upper and lower lobes have anomalous pulmonary venous drainage into the supradiaphragmatic IVC (Figs 2G-I). In Figure 3, CMR with MRA better illustrated the hypoplastic right-side pulmonary artery and the normal left-side pulmonary arteries and veins. Apart from the dextrocardia, no other coexisting cardiac anomalies were identified. In Figure 4, MRA with maximum intensity projection better characterized the vascular anomalies. Because of his asymptomatic presentation, the patient was reassured that he would most likely remain healthy and not require surgical intervention.

Figure Jump LinkFigure 3 –  A and B, Cardiovascular magnetic resonance with magnetic resonance angiogram illustrating the hypoplastic right-side pulmonary artery and the normal left-side pulmonary arteries and veins. C and D, Partial right-side anomalous pulmonary veins drain from the right upper and lower lung lobes to the supradiaphragmatic inferior vena cava through a large draining vein (C and D) and an attenuated pulmonary vein entering the left atrium and likely draining the right middle lung lobe (C). Cor-Sag = coronal-sagittal.Grahic Jump Location
Figure Jump LinkFigure 4 –  A, Magnetic resonance angiogram with maximum intensity projection of the phase-contrast angiogram characterizing the vascular anomalies (anterior view). B, In sagittal oblique direction as seen from 45° left anterior oblique view delineating the anomalous pulmonary venous drainage from the right upper and lower lung lobes to the supradiaphragmatic inferior vena cava through a large draining vein. See Figure 3 legend for expansion of abbreviation.Grahic Jump Location

  • 1. Scimitar (hypogenetic lung) syndrome is a rare congenital anomaly characterized by an anomalous pulmonary (scimitar) vein and a hypoplastic lung with ipsilateral hypoplastic pulmonary artery.

  • 2. Scimitar syndrome is commonly associated with coexisting cardiac anomalies, including dextrocardia, atrial septal defect, pulmonary vein stenosis, coarctation of the aorta, ventricular septal defect, and patent ductus arteriosus.

  • 3. Scimitar syndrome in adults is identified as an incidental finding on routine chest radiograph.

  • 4. Scimitar syndrome in an asymptomatic adult does not require treatment; surgical intervention is reserved for patients with pulmonary hypertension, severe shunting, or recurrent pulmonary infections.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Other contributions: CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.

Zylak CJ, Eyler WR, Spizarny DL, Stone CH. Developmental lung anomalies in the adult: radiologic-pathologic correlation. Radiographics. 2002;22(suppl 1):S25-S43. [CrossRef] [PubMed]
 
Berrocal T, Madrid C, Novo S, Gutiérrez J, Arjonilla A, Gómez-León N. Congenital anomalies of the tracheobronchial tree, lung, and mediastinum: embryology, radiology, and pathology. Radiographics. 2004;24(1):e17. [CrossRef] [PubMed]
 
Johri S, Dunnington GH. A 61-year-old woman with exertional dyspnea and right-sided heart enlargement. Chest. 2011;139(3):702-706. [CrossRef] [PubMed]
 
Korkmaz AA, Yildiz CE, Onan B, Guden M, Cetin G, Babaoglu K. Scimitar syndrome: a complex form of anomalous pulmonary venous return. J Card Surg. 2011;26(5):529-534. [CrossRef] [PubMed]
 
Joerg L, Kim OC, Geyer R, Maeder MT. Multimodal imaging of anomalous pulmonary venous return in an adult patient with scimitar syndrome. Eur Heart J. 2012;33(21):2679. [CrossRef] [PubMed]
 
Ciçek S, Arslan AH, Ugurlucan M, Yildiz Y, Ay S. Scimitar syndrome: the curved Turkish sabre. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2014;17(1):56-61. [CrossRef] [PubMed]
 
Hernández Pérez FJ, Fiz SS, Mirelis JG. Scimitar syndrome: the role of cardiac magnetic resonance. Rev Esp Cardiol. 2014;67(9):766. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1 –  The initial chest radiograph.Grahic Jump Location
Figure Jump LinkFigure 2 –  A-I, Serial transverse cuts of high resolution chest CT scan with contrast.Grahic Jump Location
Figure Jump LinkFigure 3 –  A and B, Cardiovascular magnetic resonance with magnetic resonance angiogram illustrating the hypoplastic right-side pulmonary artery and the normal left-side pulmonary arteries and veins. C and D, Partial right-side anomalous pulmonary veins drain from the right upper and lower lung lobes to the supradiaphragmatic inferior vena cava through a large draining vein (C and D) and an attenuated pulmonary vein entering the left atrium and likely draining the right middle lung lobe (C). Cor-Sag = coronal-sagittal.Grahic Jump Location
Figure Jump LinkFigure 4 –  A, Magnetic resonance angiogram with maximum intensity projection of the phase-contrast angiogram characterizing the vascular anomalies (anterior view). B, In sagittal oblique direction as seen from 45° left anterior oblique view delineating the anomalous pulmonary venous drainage from the right upper and lower lung lobes to the supradiaphragmatic inferior vena cava through a large draining vein. See Figure 3 legend for expansion of abbreviation.Grahic Jump Location

Tables

Suggested Readings

Zylak CJ, Eyler WR, Spizarny DL, Stone CH. Developmental lung anomalies in the adult: radiologic-pathologic correlation. Radiographics. 2002;22(suppl 1):S25-S43. [CrossRef] [PubMed]
 
Berrocal T, Madrid C, Novo S, Gutiérrez J, Arjonilla A, Gómez-León N. Congenital anomalies of the tracheobronchial tree, lung, and mediastinum: embryology, radiology, and pathology. Radiographics. 2004;24(1):e17. [CrossRef] [PubMed]
 
Johri S, Dunnington GH. A 61-year-old woman with exertional dyspnea and right-sided heart enlargement. Chest. 2011;139(3):702-706. [CrossRef] [PubMed]
 
Korkmaz AA, Yildiz CE, Onan B, Guden M, Cetin G, Babaoglu K. Scimitar syndrome: a complex form of anomalous pulmonary venous return. J Card Surg. 2011;26(5):529-534. [CrossRef] [PubMed]
 
Joerg L, Kim OC, Geyer R, Maeder MT. Multimodal imaging of anomalous pulmonary venous return in an adult patient with scimitar syndrome. Eur Heart J. 2012;33(21):2679. [CrossRef] [PubMed]
 
Ciçek S, Arslan AH, Ugurlucan M, Yildiz Y, Ay S. Scimitar syndrome: the curved Turkish sabre. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2014;17(1):56-61. [CrossRef] [PubMed]
 
Hernández Pérez FJ, Fiz SS, Mirelis JG. Scimitar syndrome: the role of cardiac magnetic resonance. Rev Esp Cardiol. 2014;67(9):766. [CrossRef] [PubMed]
 
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