What is Scimitar Syndrome?

Normal pulmonary venous circulation carries oxygenated blood from the alveolar capillaries to the left side of the heart for systemic distribution. In the Scimitar Syndrome (approximately 1-3 per 100,000 births), an anomalous vein connects between the pulmonary venous circulation and systemic venous circulation which creates a left-to-right shunt. This anomalous pulmonary venous return can be either partial (PAPVR) or total (TAPVR).

The syndrome associated with PAPVR is more commonly known as “Scimitar Syndrome”, which arises from the curvilinear pattern created on a chest radiograph by the pulmonary veins that drain to the inferior vena cava. This anomalous venous drainage of the right lung into the inferior vena cava, with hypoplasia of the right lung, creates a radiographic shadow that is Scimitar-shaped (curved sword).

Some of the symptoms of Scimitar Syndrome include cyanosis, respiratory distress, shortness of breath, rapid breathing, and rib cage muscle retraction.

Scimitar Syndrome consists of several components which include:

  • Total or partial anomalous connection of the pulmonary veins in one lung to the inferior vena cava. This connection can be above or below the level of the diaphragm. With rare exceptions, the right lung is the affected lung.
  • Variable degree of hypoplasia (small-size) and malformation of the pulmonary arteries and lung in the same side of the lung in which the pulmonary veins drain anomonously.
  • Often presence of aortic-pulmonary artery collateral arteries to the lung that is small. Pulmonary hypertension is present if these arteries are large.

Treatment for Scimitar Syndrome:

There is a wide clinical spectrum for patients with Scimitar Syndrome. The decision to intervene medically depends on the hemodynamic burden. If the amount of blood flowing to the inferior vena cava from the anomalous pulmonary veins is small, no therapy is required. If the anomalous pulmonary venous drainage is associated with a significant left-to-right shunt, surgical correction is warranted. Aortopulmonary collateral arteries can be closed either in the cardiac catheterization laboratory by placement of occluding coils or other devices, or surgically.

Source: Children’s Hospital of Boston