Invited article (415KB)	1Grech V, 2Xuereb R, 2Xuereb M, 3Manche A, 3Schembri K, 4DeGiovanni JV. Late presentation and successful treatment of classical scimitar syndrome. Images Paediatr Cardiol 2003;16:49-62
	1Dept. of Pediatrics, St Luke’s Hospital, Malta
	2Cardiology Department, St Luke’s Hospital, Malta
	3Department of Cardiothoracic Surgery, St Luke’s Hospital, Malta
	4Cardiology Department, Birmingham Children’s Hospital, UK

The most common form of partial AVPD is connection to the SVC or SVC-RA junction in association with a superior sinus venosus defect. Scimitar syndrome is rarer, with the right pulmonary vein/s draining to the inferior vena cava. This abnormal form of drainage is visible on plain chest radiography, and was first described in 1836.¹ The APVD is seen as a curvilinear density along the right heart border, similar in shape to the classic Turkish curved sword. The term ‘scimitar syndrome’ was coined by Neill in 1960 to describe the CXR appearance.² Scimitar syndrome must be differentiated from the pseudoscimitar syndrome in which an abnormal descending vein pursues an aberrant course in the right lung but drains normally into the left atrium, and from Kartagener's syndrome.

Scimitar syndrome is also known as Halasz’s syndrome, mirror-image lung syndrome, hypogenetic lung syndrome, epibronchial right pulmonary artery syndrome and vena cava bronchovascular syndrome. It occurs more commonly in females and is occasionally familial.² The left lung is very rarely involved and the reason for this is unknown.³ The true incidence of this condition is unknown since the syndrome may remain undetected in asymptomatic patients who do not undertake a CXR.

Scimitar syndrome overlaps with pulmonary sequestration and the term venolobar syndrome has been coined to include these associated pulmonary and vascular malformations.⁴

The condition is associated with:⁴

1. Partial agenesis or hypoplasia of the right lung with bronchial isomerism
2. Diverticulum or hypoplasia of the right bronchial system.
3. Hypoplasia or agenesis of the right pulmonary artery. This may cause mediastinal shift to the right side and the scimitar vein may be difficult to appreciate or even completely obscured.
4. Abnormal systemic blood supply to at least part of the right lung, most frequently the posterior basal segment of the lower lobe, usually arising from the infradiaphragmatic descending aorta.
5. Dextrocardia due to right lung hypoplasia with mediastinal shift.
6. Accessory diaphragm or eventration or partial absence of the diaphragm.
7. Phrenic cyst
8. Horseshoe lung
9. Oesophageal and gastric lung
10. Absence of the pericardium
11. Other congenital cardiac malformations (25% of cases) including ASD, ventricular septal defect, coarctation of the aorta, tetralogy of Fallot, pulmonary stenosis, absent inferior vena cava with azygos continuation to superior vena cava and persistent left superior vena cava.⁵ Moreover, the APVD may also be partially obstructed, further contributing to pulmonary hypertension.⁶

In the neonatal period with respiratory and/or cardiac failure. This is most commonly caused by pulmonary hypertension due to cardiac and/or right lung anomalies.  Treatment is surgical and outcome is dependant on the nature and severity of the anomalies.⁹ Heart failure may also be caused because of a large arterial supply from the abdominal aorta to a sequestered lobe. In these situations, cardiac catheterisation may be used to embolise the aberrant pulmonary blood supply. This not only relieves heart failure but also makes the surgical field more bloodless.

At any stage in life due to recurrent chest infections, usually affecting the right lower lobe that often has an abnormal arterial blood supply and venous drainage. Severity and frequency of chest infections is related to the degree of pulmonary hypoplasia. Lobectomy or even right pneumonectomy may be required to deal with bronchiectasis and prevent further chest infections. Affected individuals may also present with haemoptysis due to pulmonary hypertension.¹⁰

At any stage in life as an incidental finding e.g. due to the detection of a murmur or due to the evident CXR abnormalities.¹¹

Useful investigations include echocardiography, angiography and computerised chest tomography.¹² Magnetic resonance imaging also delineates abnormal vessels.

APVD with significant left to right shunting is corrected surgically, in this case, by baffling anomalous pulmonary venous return to the left atrium through the inferior vena cava or by reimplantation of the scimitar vein to the left atrium. Potential complications include acute or chronic postoperative thrombosis at the anastomotic/baffle sites.

We present a case of scimitar syndrome that presented in the late teens with a murmur. The patient (female) was well and asymptomatic, with no cardiac or respiratory problems. Echocardiography showed a dilated right heart and left to right shunting across a moderate ASD. Transoesophageal echocardiography confirmed the defect and showed left pulmonary veins draining to left atrium, but failed to demonstrate the right pulmonary veins.

Cardiac catheterisation easily demonstrated both left pulmonary veins but failed to show the right pulmonary veins (figures 1 and 2).
 

Right pulmonary artery angiogram showed classical scimitar syndrome, with right pulmonary veins joining to a descending (scimitar) vein that drained to the inferior vena cava (figures 3-5).
 

In retrospect, the scimitar vein was also visible on direct fluoroscopy (figure 6). The entire right pulmonary artery angiogram is shown in figure 7.
 

 
Saturations confirmed left to right shunting with step-up at the level of the inferior vena cava (figure 8).
 

Chest computerised tomography was performed to exclude the possibility of pulmonary sequestration. Sequestration was not present, but the descending vein could be clearly seen within the right lung (figure 11), and inferiorly coursing medially towards the inferior vena cava (figure 12).
 

Surgical repair was successfully and uneventfully carried out by baffling the orifice of the scimitar vein at its entry into the inferior vena cava to the ASD. Autologous pericardium was used (figures 13-16). The patient was placed on bypass with bicaval drainage and aortic return and cooled to 18 degrees celcius. Due to the close proximity of the hepatic vein confluence and the inferior vena cava, the latter could not be snared in order to isolate the venous return to the right atrium. Consequently, the entire corrective procedure was performed under hypothermic circulatory arrest.
 

 
References

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Contact information

Dr. Victor Grech  Consultant Paediatric Cardiologist & Editor-in-Chief, Images Paediatr Cardiol Paediatric Department  St. Luke's Hospital  Guardamangia MSD09 - Malta  victor.e.grech@gov.mt