Prenatal diagnosis of fetal aortopulmonary window by two- and four-dimensional echocardiography with spatiotemporal image correlation

Aortopulmonary window (APW) is a rare congenital heart disease which challenges most screening sonographers. The current study aims to summarize the two-dimensional (2D) and four-dimensional (4D) sonographic features in the fetal diagnosis.

Ten cases of fetal APW were retrospectively reviewed, including 6 and 4 fetuses with distal and proximal defects, respectively. In addition, 40 normal fetuses with similar gestational age were also enrolled. The angle (α) between the pulmonary artery and aorta, and the length (D) of the ductus/pulmonary artery before its convergence with aorta were measured and compared between the normal and APW fetuses, respectively. Cardiac volumes of APW fetuses were acquired with spatial temporal image correlation (STIC) technique and post-analyzed to obtain 4D rendered images.

The D and the α were smaller and greater in distal APW fetuses than those in the normal fetuses, respectively (both P < .01), while no difference presented between the proximal APW fetuses and the normal fetuses. The ductus was absent for all distal APW fetuses, while it was normal for proximal APW fetuses. In 9 of 10 fetuses (90%), the 4D rendered image could be successfully obtained, which clearly showed the abnormal blood communication between the two great arteries in space.

It is essential to scan around the three-vessel view and three-vessel trachea view to identify fetal APW using grayscale and color Doppler echocardiography. Distal APW is always with an increasing angulation between aorta and the pulmonary artery, and without the presence of normal ductus. 4D STIC technique may provide additional spatial relationships of the great arteries and thus help the diagnosis and consultation.