The Three-Vessel View in the Fetal Mediastinum in the Diagnosis of Interrupted Aortic Arch

Interruption of the aortic arch (IAA) is difficult to detect and diagnose in utero. However, prenatal diagnosis may be beneficial because IAA is rapidly fatal (median age, 10 d) if left uncorrected. Our objective was to review the direct and indirect echocardiographic markers associated with IAA, focusing on the importance of the three-vessel view (3VV), which is obtained during routine ultrasound examination to rule out malformations. We analyzed the fetal echocardiograms of nine fetuses and compared them with 56 normal controls. In each fetus, there was a large discrepancy between the diameter of the larger, dilated pulmonary artery (PA) and smaller, narrow aortic arch (Ao). The calculated ratio of PA/Ao in fetuses with IAA was 2.6 ± 0.4 compared with 1.1 ± 0.09 in normal controls (p < 0.0001). The calculated ratio of PA/Ao in fetuses with IAA type A was 2.1 ± 0.09 and IAA type B 2.9 ± 0.2 (p = 0.0007). Discrepancy between PA/Ao diameters should raise the suspicion of aortic arch anomalies and a large discrepancy is a nearly pathognomonic sign of IAA type B.