Imaging description

Pseudocoarctation is characterized by pseudostenoses of the descending thoracic aorta just distal to the origin of the left subclavian artery at the level of the ligamentum arteriosum. Both contrast-enhanced CT and magnetic resonance angiography are useful diagnostic imaging tests with distinct diagnostic advantages for non-invasive assessment of the abnormality. Multiplanar reformatted images are particularly helpful in differentiating this entity from true coarctation with demonstration of “kinking and buckling” and an elongated descending aorta with absence of collateral circulation (Figures 27.1 and 27.2). MRI has the added advantage of providing measurement of the pressure gradient before and after the area of pseudocoarctation using phase-contrast imaging as well as estimates of collateral flow volume. In cases of pseudocoarction, the pressure gradient should be negligible, whereas it will be elevated in coarctation with intervention considered at a threshold of 15–20 mmHg.

Importance

Pseudocoarctation, a rare congenital anomaly, manifests as kinking of the aortic arch due to its redundancy. Recognition of this abnormality is important since it may be mistaken for true coarctation, aneurysm, or mediastinal neoplasm. Additionally, pseudocoarctation is associated with other abnormalities such as bicuspid aortic valve, patent ductus arteriosus, ventricular septal defect, and anomalies of the left subclavian artery (Figure 27.3).

Typical clinical scenario

Pseudocoarctation is usually asymptomatic and may be an incidental finding on imaging. Findings of esophageal compression with dysphagia and weight loss may also be seen. Patients may be monitored for aneursymal dilatation in the affected areas.

Differential diagnosis

Differential diagnosis for pseudocoarctation includes true coarctation, aneurysm, and mediastinal neoplasm. Pseudocoarctation is differentiated from true coarctation of the aorta by the absence of significant hemodynamic obstruction and collateral vessels.