Scimitar syndrome is a rare form of CHD consisting in anomalous pulmonary venous connection to the inferior caval vein often associated with a hypoplastic right lung.Reference Woodring, Howard and Kanga 1 It is also frequently associated with aortopulmonary collateral arteries to the hypoplastic lung and rightwards shifting of the heart into the right chest, as well as other anomalies such as horseshoe lung.
Herein, we report a rare variant of Scimitar syndrome with drainage of the anomalous right lower pulmonary vein – meandering vein – into the right superior pulmonary vein.
Case report
A 60-year-old woman, who underwent echocardiography as part of a diagnostic workup for arterial hypertension, was found to have severe stenosis of a bicuspid aortic valve. She had been diagnosed with Scimitar syndrome at the age of 23 years. The chest radiograph (Fig 1) showed a curved tubular opacity in the right lung field that was thought to be a Scimitar sign. A cardiac CT was performed as preoperative workup (Fig 2). The CT revealed an aortic root dilatation and an uncommon variant of Scimitar syndrome related to a meandering vein associated with a hypoplastic right lung. Indeed, the right inferior pulmonary vein had an aberrant trajectory, connected first by a thin septa to the middle lobar vein and then drained into the upper root of the right superior pulmonary vein (Fig 3). Furthermore, we noted hypoplasia of the middle lobar bronchus and of segments of the basal pyramide and a cardiac accessory bronchus of the middle lobe. In addition, the heart was displaced rightwards, owing to the hypoplastic right lung. Finally, we identified a systemic vessel, most probably a diaphragmatic artery, that connected to the meandering vein described above.
Figure 1 The chest radiograph showing a small right lung with a curved tubular opacity (arrow) in the right lung field.
Figure 2 A computed tomography coronal reformat showing the anomalous meandering vein (arrow).
Figure 3 CT multiplanar volume rendering reformat showing the anomalous meandering vein which drains to the upper root of the right superior pulmonary vein (arrow).
The patient underwent successful total aortic root replacement using a Medtronic Freestyle stentless bioprothesis (Medtronic, Minneapolis, Minnesota, United States of America). The anomalous meandering vein and aortopulmonary collateral (systemic vessel) were left untouched during surgery as the meandering vein was draining into the left heart – via the superior lobar vein – and the aortopulmonary collateral was considered haemodynamically not significant.
The patient was discharged at home in good general condition on post-operative day 7.
Discussion
Pulmonary venous anomalies include many anatomic variations, with a wide range of clinical presentations and outcomes. There are different classifications of pulmonary venous anomalies. The anomalies may be grouped into three categories, such as the anomalous pulmonary venous return with or without anomalous course, the anomalous course of pulmonary veins with normal venous return, and stenotic connections.
Scimitar syndrome is a specific form of partial anomalous pulmonary venous connection and concerns the first group category of pulmonary venous anomalies. Scimitar syndrome consists of anomalous pulmonary venous connection to the inferior caval vein, frequently associated with aortopulmonary collateral arteries to the hypoplastic right lung and cardiac dextroposition, as well as other anomalies such as horseshoe lung.
In the Scimitar syndrome, the anomalous pulmonary vein most often drains into the inferior caval vein below the right hemidiaphragm; less commonly, it may drain into the suprahepatic portion of the inferior caval vein, hepatic veins, portal vein, azygos vein, coronary sinus, or right atrium.Reference Fraser, Muller and Colman 2 , Reference Heitzman 3 The syndrome is named for the anomalous vessel’s resemblance to the scimitar, which is a Turkish sword with a curved blade.Reference Neill, Ferencz, Sabiston and Sheldon 4
The term Scimitar variant has been used to describe the spectrum of malformations that lack the typical features of the Scimitar syndrome. Thus, a scimitar vein draining into the left atrium is a rare form of Scimitar variant with only a few cases described in the literature.Reference Odenthal and Sarikwal 5 – Reference Bo, Carvalho and Cheastry 8 This condition is called also “meandering pulmonary vein”. In this variant of Scimitar syndrome, the meandering pulmonary vein – the anomalous right lower pulmonary vein in our situation – has an abnormal course, which forms the Scimitar sign on chest radiograph, with normal venous return to the left atrium.
During early development, by 30–32 days after conception, the pulmonary venous plexus loses most of its connections with the splanchnic plexus, and blood flows from the pulmonary venous plexus through the common pulmonary vein to the left atrium.Reference Salazar-Mena, Salazar-Gonzalez and Salazar-Gonzalez 10 Yoo et alReference Yoo, Al-Otay and Babyn 9 and Salazar-Mena et alReference Salazar-Mena, Salazar-Gonzalez and Salazar-Gonzalez 10 propose that delayed union of the common pulmonary vein with the pulmonary venous plexus could result in pulmonary venous connections with both the umbilico-vitelline veins and the left atrium. This condition may explain cases of double drainage into the inferior caval vein and the left atrium. The connection to the left atrium is subsequently obliterated in most cases. Rarely, its connection to the left atrium persists, with obliteration of its connection to the inferior caval vein,Reference Yoo, Al-Otay and Babyn 9 , Reference Salazar-Mena, Salazar-Gonzalez and Salazar-Gonzalez 10 resulting in pulmonary veins connected only to the left atrium but having an anomalous route through the lungsReference Bo, Carvalho and Cheastry 8 . Patients may have associated cardiovascular anomalies, most commonly atrial septal defect, ventricular septal defect, tetralogy of Fallot, patent ductus arteriosus, coarctation of the aorta, and pulmonary stenosis.
Alternatively, Furuya et alReference Furuya, Kaku and Yasumori 7 have reported a case with an anomalous venous return to the left inferior pulmonary vein. In the present case, we report a patient with Scimitar Syndrome and an anomalous vein draining into the right superior pulmonary vein, “meandering vein”. This anomaly was furthermore associated with a bicuspid aortic valve and an aortic root aneurysm.
In Scimitar Syndrome, hypoplasia or the absence of the right pulmonary artery and aortopulmonary collateral also usually are present.Reference Fraser, Muller and Colman 2 , Reference Heitzman 3 , Reference Bo, Carvalho and Cheastry 8 In our case, the right pulmonary artery was hypoplastic, and we identified small aortopulmonary collateral – a systemic vessel, most probably diaphragmatic artery, that arrived to the anomalous meandering vein.
Patients with Scimitar Syndrome who have no or only mild symptoms require no therapy.Reference Fraser, Muller and Colman 2 , Reference Heitzman 3 , Reference Furuya, Kaku and Yasumori 7 Our patient had also no symptoms related to her Scimitar Syndrome; the meandering vein was draining into the left heart – to the superior lobar vein – and the aortopulmonary collateral was considered haemodynamically not significant. Therefore, we decided not to correct this anomaly during the surgery.
To the best of our knowledge, the present case is the first report of a Scimitar syndrome variant consisting in hypogenetic lung syndrome with an anomalous venous return to the right superior pulmonary vein and associated with a bicuspid aortic valve and aortic root aneurism. Careful iconographic analysis is required for adequate recognition and description of these uncommon variants.
Acknowledgements
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This research received no specific grant from any funding agency, commercial, or not-for-profit sectors.
Conflicts of Interest
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