Scimitar syndrome is characterized by a hypoplastic right lung drained by an anomalous vein into the inferior vena cava, known as a scimitar vein. It presents with a partial anomalous pulmonary venous return most commonly on the right side. Associated findings include congenital heart defects, diaphragmatic anomalies, and vertebral anomalies. Radiological imaging plays an important role in diagnosis, with chest x-rays sometimes showing the scimitar vein and reduced lung volume. CT and MRI are useful to precisely map the anomalous pulmonary vein and associated abnormalities.

1. Radiological imaging of Scimitar Syndrome.
Dr/ ABD ALLAH NAZEER. MD.

2. Scimitar syndrome, also known as hypogenetic lung syndrome,is
characterized by a hypoplastic lung that is drained by an anomalous
vein into the systemic venous system. It is a type of partial
anomalous pulmonary venous return and is one of several findings
in congenital pulmonary venolobar syndrome.
Pathology
It is essentially a combination of pulmonary hypoplasia and partial
anomalous pulmonary venous return (PAPVR). It almost exclusively
occurs on the right side.
Hemodynamically, there is an a cyanotic left to right shunt. The
anomalous vein usually drains into:
inferior vena cava: most common
right atrium
portal vein
The aorta frequently perfuses the lung, but the bronchial tree is still
connected, and thus the lung is not sequestered.

3. Associations
congenital heart disease, e.g. ASD, VSD, tetralogy of Fallot, PDA
ipsilateral diaphragmatic anomalies, e.g. accessory
diaphragm, diaphragmatic hernia
localized bronchiectasis
horseshoe lung
vertebral anomalies, e.g. hemivertebrae
genitourinary tract abnormalities
pulmonary sequestration
Clinical Findings
Scimitar syndrome may be diagnosed in infancy because of the associated
symptomatic congenital cardiovascular disease (25-50%). Associated
congenital cardiac anomalies include: atrial septal defect, ventricular septal
defect, patent ductus arteriosus, tetralogy of Fallot, coarctation of the
aorta, hypoplasia of the left heart, and various endocardial cushion defects.
Some patients may present with hemoptysis and/or recurrent pulmonary
infection. Approximately 50% of patients are asymptomatic and diagnosed
incidentally on chest radiography acquired for unrelated reasons. Women
are slightly more often affected with a female-to-male ratio of 1.4:1.

4. Radiographic features
The diagnosis is made by transthoracic or transesophageal echocardiography,
angiography, or by CT or MR angiography.
Plain radiograph
Chest radiographic findings are that of a small lung with ipsilateral mediastinal
shift, and in one third of cases, the anomalous draining vein may be seen as a
tubular structure paralleling the right heart border in the shape of a Turkish
sword (“scimitar”).
The right heart border may be blurred.
Small right lung and hemithorax.
Mediastinal shift to the right with dextroversion of the heart.
Indistinct right cardiac border
Blunted costo phrenic angle
Vertically-oriented curved tubular opacity (anomalous draining vein) in right
inferior thorax coursing towards right cardiophrenic angle.
Diminished right pulmonary vascularity.
MDCT / MRI
Allows optimal visualization of the anomalous draining vessel and its course and
drainage into IVC, hepatic circulation, right atrium, or coronary sinus
Non-invasive assessment of left-to-right shunts with velocity-encoded cine MRI

5. The right hemithorax is hypoplastic. Also, a tubular structure is seen in the lower right lung, which has
the shape of a scimitar; the findings are suggestive of Scimitar's syndrome (pulmonary venolobar
syndrome or hypogenetic lung syndrome), a type of partial anomalous pulmonary venous return
(PAPVR). The heart is displaced to the right. The left pulmonary artery is very prominent.

6. Scimitar Syndrome.

7. Scimitar Syndrome.

8. Scimitar Syndrome.

9. A chest radiography of a patient with scimitar syndrome showing a left-side anomalous
pulmonary vein (Panel A), which was confirmed by magnetic resonance imaging (Panel B).

10. Scimitar syndrome. Newborn with tachypnea. A, Frontal chest radiograph demonstrates dextrocardia with decreased aeration of the
right lung. B, Subsequent coronal reformatted chest CT image shows shift of the heart into the right side of the chest with the left
ventricle (LV) apex to the left and right ventricle (RV) to the right consistent with dextroposition or secondary dextrocardia. C, A posterior
coronal reformatted image shows anomalous pulmonary venous drainage of the left lung to the IVC with a scimitar vein
(arrow). D, Coronal minimum intensity projection image demonstrates that the right main stem bronchus bifurcates to support two
lobes of the lung separated by a single fissure (arrow) consistent with absence of the right upper lobe.

11. Baffle obstruction after repair of scimitar syndrome; 24-year-old with exercise intolerance. Coronal maximum
intensity projection (A) from MRA demonstrates anomalous pulmonary venous drainage (arrow) of the entire right
lung to the IVC. After surgical construction of a baffle to connect the pulmonary venous drainage to the left atrium,
coronal maximum intensity projection image from MRA (B) demonstrates complete baffle obstruction (arrow). The
baffle also underwent dehiscence, allowing the scimitar vein to connect to the IVC, which is markedly dilated.

12. Scimitar syndrome with a hypoplastic right lung.

14. Scimitar Syndrome

16. Chest radiograph (left) and chest computed tomography (right, A–D) in a 4-day-old boy with scimitar syndrome. Although
right lung hypoplasia and shift of the mediastinal structures to the right are well delineated on the chest radiograph, the
anomalous pulmonary venous return (“scimitar vein”; black arrowheads) cannot be readily appreciated. The scimitar vein is
better appreciated with computed tomography (performed at age 4 days; white arrowheads), which also confirmed right lung
hypoplasia and mild compression of the right lower lobe. Additional partial anomalous pulmonary venous return vessels were
not identified, possibly owing to the small anatomic scale at that age and a lack of information on blood flow direction.

17. Scimitar Syndrome.

18. A 78-yr-old female with history of chronic dyspnea and scimitar syndrome. Contrast enhanced computed tomography
(CT) was acquired with 3-mm sections. a) Axial CT image at the level of the left atrium shows absence of left upper
pulmonary vein (arrow). b) Axial CT image at the level of the right inferior pulmonary vein (arrow) shows
enlargement of the vein that enters the right atrium (star). c) Coronal multiplanar reformation shows the
enlargement and abnormal position of the right pulmonary vein (arrow) and the continuity with the right atrium
(star). d) Three-dimensional surface shaded display view in a coronal projection of the malformation (arrow).

19. Scimitar syndrome, (a) Chest CT shows hypoplasia of the right lung, mediastinal shift and abnormal vascularization of
the right lung; (b) MDCT chest showing small right pulmonary artery (white arrow); (c) MDCT chest showing systemic
arterial supply of the right lung; (d) MDCT chest showing absence of right pulmonary venous drainage to left atrium.

20. Scimitar syndrome in a 53-year-old man. Coronal and sagittal maximum-intensity-projection reformatted image
shows a large anomalous vein draining into the inferior vena cava, below the level of the right diaphragm (*).

21. Multislice, single-phase, fast imaging with steady-state precession (TrueFISP) sequence on coronal (A and B) and axial
(C and D) planes shows an anomalous vessel in the right lung (arrows) connected to the inferior vena cava.

22. A, Maximum-intensity projection of the phase-contrast angiogram in sagittal oblique direction as seen from 30° left anterior
oblique view. In addition to the pronounced scimitar vein (ScimV), the hypoplastic right pulmonary artery (*), an additional
partial anomalous pulmonary venous return vein in the right upper lobe (open white arrow), and the anomalous systemic
artery from the celiac trunk to the right lower lung (white arrowheads) can be appreciated. B, Posterior view of segmented PC-
VIPR angiography data with color-shaded surface display. For detailed understanding and ready apprehension, the oxygenized
arterial (red), oxygenized partial anomalous pulmonary venous return (pink), deoxygenized venous and right ventricular (blue)
structures, and portal venous system (yellow) were color-coded. SVC indicates superior vena cava; AAo, ascending aorta; LPA,
left pulmonary artery; LA, left atrium; RA, right atrium; IVC, inferior vena cava; and DAo, descending aorta.

23. MRI of Partial Anomalous Pulmonary Venous Return - Scimitar Syndrome

24. Scimitar syndrome: multislice computer tomography with three-dimensional reconstruction.

25. Thank You.