Purpose or Case Report: Scimitar syndrome, also known as congenital pulmonary venolobar syndrome, is a rare variant of partial anomalous pulmonary venous return (PAPVR), typically involving the right-sided pulmonary veins. Scimitar syndrome is usually characterized by drainage of the right lung by an anomalous right pulmonary vein, which may empty into the IVC, azygos vein, hepatic vein, coronary sinus, or right atrium. On frontal chest radiograph, the anomalous right pulmonary vein appears as a curvilinear density in the right lung, similar to the shape of a Turkish scimitar sword. Associated imaging features of Scimitar syndrome are variable, but often include right lung hypoplasia and systemic arterial supply to the abnormal right lung segments. Left-sided Scimitar syndrome is extremely rare, with only a handful of cases reported in the literature. In this report, we present a case of left scimitar syndrome with anomalous left pulmonary vein draining into the left renal vein.

A 3-year-old female twin, born at term, presented to pediatric cardiology for evaluation of an asymptomatic murmur detected during a routine well-child check. Physical exam revealed a benign Still's murmur. However, ECG demonstrated right ventricular hypertrophy, warranting further evaluation with echocardiogram. Echocardiogram showed moderate left pulmonary artery hypoplasia and poor delineation of the left pulmonary veins. Subsequent cardiac MRI demonstrated absence of normal left pulmonary veins draining into the left atrium and Qp:Qs of 1.5, raising concern for a left-to-right shunt in the setting of anomalous left pulmonary venous return.

Further evaluation with cardiac CTA delineated drainage of the entire left lung by a single vertical anomalous left pulmonary vein which coursed below the diaphragm into the left renal vein. The left renal vein then emptied into a moderately dilated IVC. Normal right sided pulmonary venous return into the left atrium was noted. No fissure was visualized in the left lung, which appeared to contain a single lobe. No definite systemic arterial supply to the left lung was identified on cardiac CTA. Imaging findings were compatible with left-sided scimitar syndrome.

After discussion of the case at multidisciplinary conference, surgical management was deferred, as the patient was asymptomatic. The patient will be followed with yearly echocardiogram and ECG to monitor for developing stenosis of the anomalous left pulmonary veins.
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