Prenatal Images of the Truncus Arteriosus With an Interrupted Aortic Arch

Abstract

A 31-year-old primigravida was referred to our unit due to suspicion of a cardiac anomaly on obstetric screening ultrasound at 28 weeks of gestation. Although fetal echocardiography in the four-chamber view showed atrioventricular concordance and normal cardiac size, an outflow tract abnormality was noted. A single large vessel arising from the left and right ventricles and a ventriculoseptal defect (VSD) were identified (Fig. 1a; Movie 1). The main pulmonary trunk was not detected, and bilateral pulmonary arteries arose from opposite sides of the single large vessel. This unique outflow tract was therefore identified as a truncus arteriosus (TA). Color Doppler sonography showed mild truncal valve regurgitation and no truncal valve stenosis (Movie 2). In the sagittal view, the ascending aorta appeared hypoplastic, and there was interruption between the left subclavian artery and the descending aorta arising from the ductus arteriosus (Fig. 1b, c; Movie 3). Taken together, these findings led a diagnosis of TA associated with interrupted aortic arch (IAA), which corresponded to Van Praagh classification type 4A. No associated anomalies were identified, and fetal cardiac function showed no remarkable changes. At 34 weeks gestation, a female neonate weighing 1,968 g was delivered vaginally after rupture of membranes, with Apgar scores of 6 at 1 min and 9 at 5 min. Neonatal echocardiography and computed tomography confirmed the prenatal diagnosis of TA-IAA (Fig. 2). TA is an uncommon cardiac anomaly accounting for 0.7 % of all congenital heart disease, and concomitant IAA is found in approximately 15 % of children with TA [2]. Thus, the combination of TA-IAA is an extremely rare clinical entity, and a case report of prenatally diagnosed TA-IAA is limited. Marasini et al. [4] described a case of TA-IAA with severe truncal valve regurgitation. However, the case was electively terminated by severe hydrops fetalis. Van Praagh and Van Praagh proposed a classification system for TA according to two commonly associated abnormalities of the great arteries. Type 1 is characterized a short pulmonary trunk originating from the TA. Type 2 is defined by right and left pulmonary arteries originating separately from the TA. Type 3 includes cases with no truncal origin of one pulmonary artery, with the blood supply to that lung from the ductus arteriosus or from a collateral artery. Finally, type 4 is associated with underdevelopment of the aortic arch, including tubular hypoplasia, discrete coarctation, or complete interruption. The Van Praagh classification also specifies the presence of a VSD (type A) or the absence of a VSD (type B) [5]. Our case, the common form of TA with IAA and an associated VSD, is thus classified type A4. Although surgical TA repair during the neonatal and early infant period has become standard practice, the management of neonates with TA-IAA remains challenging [2]. The largest study reported a mortality rate of 68 % during the neonatal and infant period for a cohort of 50 TAIAA patients [3]. Several studies have identified factors Electronic supplementary material The online version of this article (doi:10.1007/s00246-012-0469-3) contains supplementary material, which is available to authorized users.