The complex pulmonary venolobar anomalies grouped together within the Scimitar syndrome have been recognized for well over a century. In the classic syndrome, there is displacement of the heart to the right, and a prominent curved vein draining part of the right lung to the inferior caval vein, this venous malformation producing the scimitar shadow identified on chest radiographs.
The term “scimitar variant” has also been used for many years, describing a number of anatomic anomalies that are similar to the classical arrangement, but lack one or more of the features making up the complete syndrome. The variants include isolated hypoplasia of the right lung, with normally shaped pulmonary veins, the horseshoe lung, accessory diaphragm, and others. The rarest includes drainage of a vein that produces a scimitar shadow to the left atrium rather than the inferior caval vein.
Case report
Our patient was referred at the age of two months, with the diagnosis of an unrestrictive ventricular septal defect, an atrial septal defect of moderate size, failure to thrive, repeated lung infections, and inability to wean from the ventilator. The patient was started on antifailure medications, including frusemide, captopril, digoxin, and an infusion of dobutamine. The older brother was known to us, and had been diagnosed with classical Scimitar syndrome. He was under follow-up in our clinics.
The patient was transferred to our centre in cardiac failure, ventilated, and weighing only 2.7 kilograms. The chest radiograph showed cardiomegaly, and congested lung fields. The electrocardiogram revealed biventricular hypertrophy. Cross-sectional echocardiography showed an atrial septal defect within the oval fossa of moderate size, a large unrestrictive and confluent perimembranous ventricular septal defect, and depressed ventricular function. It also revealed two additional findings of interest, namely a systemic collateral artery originating from the abdominal aorta which supplied the right lower lobe of the lung, and an abnormal tortuous course of the right lower pulmonary vein, which formed a loop before entering the left atrium (Fig. 1). Computed tomographic angiography of the chest was not conclusive, and suspicion remained that the right lower pulmonary vein drained to the inferior caval vein. Cardiac catheterization was therefore performed, initially for diagnosis, but also for therapy. The investigation confirmed the curvilinear course of the right lower pulmonary vein, which formed a loop before connecting with the left atrium. We proceeded, therefore, to coil the collateral artery, using three detachable coils together with two Gianturco coils (Fig. 2). The patient was then taken to the operating room, where a Gore-Tex patch was used to close the ventricular septal defect, the atrial septal defect being closed by direct suturing.
Figure 1. The right lower pulmonary vein loops then enters the left atrium. (*Meandering pulmonary vein, LA – left atrium, RA – right atrium, RV – right ventricle).
Figure 2. Angiogram showing the collateral artery from the abdominal aorta which supplies the sequestered right lower lobe. The meandering pulmonary vein loops before it enters the left atrium. (*Meandering pulmonary vein, Ao – abdominal aorta, C – collateral, LA – left atrium, SL – sequestered lobe).
The patient improved postoperatively, and was safely extubated. The pulmonary congestion improved markedly, and she was discharged in good condition on frusemide and captopril. We continue to follow her in the clinic, and her progress is excellent.
Discussion
In the classical form of the Scimitar syndrome, there is hypoplasia of the right lung, shift of the heart to the right, hypoplasia of the right pulmonary artery, an abnormal collateral artery supplying the right lower lobe of the lung, and drainage of the pulmonary veins from that lobe to the inferior caval vein, the abnormal vein taking a course resembling the scimitar.1, 2 Familial cases have been reported.3
Variants of the classical arrangement are well recognized when the scimitar vein takes an abnormal course, but drains eventually to the left atrium.4–7 In our case, the anomalous course of the vein was not obvious on the chest radiograph, probably because it was masked by the enlarged heart. As far as we know, it was Goodman et al.8, 9 who first named the condition the meandering pulmonary vein. Others have called it a pseudo-Scimitar sign.10 In the earliest reports, the condition was an isolated finding. Tortoriello and colleagues1 reported drainage to both the inferior caval vein and the left atrium. Magnetic resonance imaging was advocated for noninvasive diagnosis, cardiac catheterization being used mainly for occlusion of the systemic collateral artery.1 To the best of our knowledge, our patient is the first reported in the English literature with associated intracardiac shunting, and the first with two forms of the Scimitar syndrome in the same family. This differing morphology illustrates the genetic variability of abnormalities of the pulmonary venous system, which needs to be elaborated more with further studies.
