Scimitar Syndrome

Scimitar syndrome is characterized by a combination of cardiopulmonary anomalies including partial anomalous pulmonary venous return connection of the right lung to the inferior caval vein leading to the creation of a left-to-right shunt.

Epidemiology

The prevalence is estimated at between 1/100,000 and 1/33,333 live births. Females seem to be more frequently affected than males.

Clinical description

In the majority of cases, the disease manifests in the first months of life. In the neonatal period, the disease presents with congestive cardiac failure, most commonly due to pulmonary hypertension and respiratory distress. The right lung is most frequently involved. Variable degrees of hypoplasia and malformations of the pulmonary arteries are found in the affected lung, as well as arterial supply from the aorta, which can also arise above or below the diaphragm. The heart itself is usually right-sided. Rarely, the disease may manifest with a small shunt, a cardiac murmur, and recurrent respiratory infections in children and adults. About one-fourth of affected patients have associated congenital heart disease (aortic coarctation, tetralogy of Fallot, patent arterial duct or ventricular septal defect; see these terms). Other reported associated anomalies include bronchogenic cysts, horseshoe lung, accessory diaphragm and hernias.

Etiology

The etiology is not completely understood. In several patients with total anomalous pulmonary venous return, the gene locus has been mapped to chromosome 4q12.

Diagnostic methods

The diagnosis is based on clinical presentation and transthoracic or transesophageal echocardiography, angiography, computed tomography and magnetic resonance angiography. The characteristic feature on chest radiographs, giving the condition its name, is a lesion in the shape of a scimitar (a type of curved Turkish sword).

Differential diagnosis

Scimitarsyndrome must be differentiated from pseudoscimitar syndrome (abnormal descending vein draining into the left atrium) and from Kartagener syndrome (see this term).

Antenatal diagnosis

Prenatal diagnosis is feasible by fetal echocardiography. Rarely, Scimitar syndrome is diagnosed incidentally in older children and adults who undergo chest radiography for diverse reasons.

Management and treatment

Management depends on the hemodynamic state. No therapy is required if the amount of blood flowing to the inferior caval vein is small. In case of significant left-to-right shunt and pulmonary hypertension, surgical correction is warranted, and can include repair of the anomalous venous return, ligation of collateral arteries, and right pneumonectomy.

Prognosis

When diagnosed in infancy, the syndrome is associated with significant mortality due to severe respiratory insufficiency, cardiac failure, and pulmonary infections.