Scimitar syndrome (SS) is a rare congenital heart defect (CHD) with a frequency of 1–3 cases per 100,000 live births and a suspected autosomal inheritance.

It results in a partial to total anomalous venous drainage of the right lung into the inferior vena cava (IVC). SS may be associated with atrial septum defects (ASD), aberrant systemic arterial supply (SAS) to the right lung through aortopulmonary collaterals and other heart defects. Anatomical sequelae include right lung hypoplasia and left to right shunting. This can lead to recurring lower respiratory tract infections (LRTI) and right ventricular volume overload causing pulmonary artery hypertension and right ventricular failure. Clinical presentation can be highly variable. Severe forms present as cyanosis and acute heart failure of the new-born or infant. Dyspnoea on exertion is a possible common symptom. Mild forms may be incidental findings in asymptomatic adults. Diagnosis can be confirmed by echocardiogram or computed tomography showing the anomalous venous return. Treatment depends on symptom severity and may include correction of venous return in cases of severe heart failure. Patients with mild symptoms will usually be treated conservatively with diuretics and standard chronic heart failure medication.