Scimitar Syndrome

At a glance

Congenital anomalous venous drainage of the right pulmonary veins into the inferior vena cava, associated with hypoplasia or aplasia of one or more lobes of the right lung.

Synonyms

Scimitar Anomaly; Halasz Syndrome; Congenital Venopulmonary Syndrome; Felson Venolobar Syndrome.

History

The name Scimitar Syndrome originates from the anomalous pulmonary vein on the right side, which drains into the inferior vena cava. This vein is sometimes visible on the radiograph of the chest resulting in a curvilinear shadow just above the right diaphragm. The shape of this shadow resembles a scimitar, a saber typically used by Arabs and Turks.

Incidence

1:100,000 live births, female predominance.

Pathophysiology

Commonly mutation on locus 4q12. Anomalous venous drainage of the right lung into the inferior vena cava represents a large left-to-right shunt. If an atrial septal defect is present and is not restrictive, right-to-left shunting occurs at the atrial level and compensates for the shunt caused by the anomalous pulmonary venous drainage. The left side of the heart is volume underloaded while the right side has an increased load. The Scimitar Syndrome is associated with pulmonary artery hypoplasia or atresia, predisposing to right ventricular failure. Obstruction of the anomalous venous drainage may occur at the level of the diaphragm or at insertion into the inferior vena cava, resulting in pulmonary venous congestion and pulmonary hypertension.

Diagnosis

Cyanotic heart disease in presence of “scimitar sign” on chest radiograph. Echocardiography is nonspecific. Anomalous venous drainage confirmed by cardiac catheterization.

Clinical aspects

Failure to thrive, cyanosis, tachycardia, signs and symptoms of right ventricular failure. Auscultation may reveal fixed, wide splitting of the second heart sound, a diastolic murmur of tricuspid origin, and a pulmonary ejection murmur in the presence of pulmonary hypoplasia. Presentation may be delayed in the presence of a nonrestrictive atrial septal defect until growth results in the atrial septal defect becoming restrictive causing a fall in arterial oxygen pressure (PaO₂). The ECG shows right axis deviation and signs of right ventricular strain. The anomalous vein(s) cause a vertical scimitar shape on chest radiograph.

Precautions before anesthesia

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