Scimitar Syndrome

Anatomy
- In a rare manifestation of PAPVC, Scimitar syndrome involves anomalous drainage of some or all of the right pulmonary veins to the IVC. There is often accompanying right lung hypoplasia and frequent aortopulmonary collaterals to the right lung. The heart may be shifted into the right chest (dextroposed) due to right lung hypoplasia. The anomalous pulmonary veins are often seen as a curved (like a scimitar) radiopacity on CXR.

Pathophysiology
- The anomalous pulmonary venous drainage causes a right ventricular volume load; may be minimal if diminished flow through right lung. Mild hypoxemia may occur secondary to right to left flow across a PFO or small ASD.
- Right lung hypoplasia along with abnormal arterialization often creates pulmonary hypertension.
- Right lung pathology, including frequent pneumonias, are common.

Repair of Scimitar Vein

Operative considerations
- Repair of the anomalous scimitar drainage includes resection of the native atrial septum and baffling of the scimitar vein through the IVC and RA to the left atrium. This is often done through a 2 patch (inverted Warden repair).
- To address areas of potential obstruction (see stars in inset), a recent modification (3 patch repair) includes an additional patch to augment the angle of entry into the IVC, resection of the limbus of the RA, closure of the ASD using a large patch (shown), and a third patch to augment the IVC.

Postoperative considerations
- Was the patient clinically well preoperatively?
  - If so, postoperative recovery should be rapid.
- Does the patient have signs of pulmonary hypertension?
  - If so, monitor for signs if RV failure, prevent atelectasis, consider pulmonary vasodilators if deteriorating.
- How much flow goes to the right lung (usually on lung scan)?
  - If <25%, pulmonary hypertension and significant dead space ventilation fraction may be expected.
- Monitor for signs of right lung infection, which may occur.
- Is there evidence of pulmonary vein obstruction?
  - There is typically no gradient following repair. However, pulmonary vein obstruction may develop over time at the scimitar-IVC junction, within the RA at the limbus, or at the junction with the native atrial septum (if it is subtotally resected).

References