Eponym. Scimitar syndrome

Abstract

Scimitar syndrome is a rare congenital anomaly, characterized by partial or complete anomalous pulmonary venous drainage of the right or left lung into the inferior vena cava. The syndrome is commonly associated with hypoplasia of the right lung, pulmonary sequestration, persisting left superior vena cava, and dextroposition of the heart. The pathogenesis of the syndrome is unclear, but it seems to originate from a basic developmental disorder of the entire lung bud early in embryogenesis. Two main forms of scimitar syndrome have been described. Signs and symptoms can start during infancy (infantile form) or beyond (childhood/adult form). The infantile form generally presents within the first 2 months of life with tachypnea, recurrent pneumonia, failure to thrive, and signs of heart failure. The diagnosis of scimitar syndrome is usually made based on the characteristic chest X-ray films and can be confirmed by angiography; however, it is now done mostly by transthoracic or transesophageal echocardiography, noninvasive computed tomography, or magnetic resonance angiography. Fetal echocardiography using three-dimensional power Doppler imaging permits prenatal diagnosis. Most frequently, patients are asymptomatic in the absence of associated abnormalities and can be followed conservatively. For patients with congestive heart failure, repeated pneumonia, or pulmonary-to-systemic blood flow ratios greater than 1.5 and pulmonary hypertension, it is important to reroute the anomalous right pulmonary veins and repair the associated cardiac defects in order to avoid progression to right ventricular failure. The triad of respiratory distress, right lung hypoplasia, and dextroposition of the heart should alert the clinician to think of scimitar syndrome.