Prenatal diagnosis and outcome of right aortic arch without significant intracardiac anomaly.

BACKGROUND

Right aortic arch (RAA) is usually associated with the presence of a significant congenital heart disease, usually a conotruncal defect, which determines the postnatal outcome. In the absence of such cardiac defects, the significance of RAA has not been determined. The aims of this study were to evaluate the significance of recognizing RAA in fetuses with normal or near normal intracardiac anatomy and to determine which associations may be present.

METHODS

A retrospective study was completed of all fetuses diagnosed with RAA with normal or near normal intracardiac anatomy between 1999 and 2011. The aim was to evaluate the presence of RAA with complete ultrasonic evaluation using two-dimensional imaging complemented by the Doppler color flow technique, paying particular attention to the three-vessel and tracheal view. We compared the prenatal findings with the postnatal outcomes and management of this cohort of fetuses.

RESULTS

Among 16,450 fetal echocardiograms, 58 fetuses (0.35%) were diagnosed with RAA with normal or near normal intracardiac anatomy. Gestational age at diagnosis ranged from 19 to 34 weeks (mean, 23 weeks). Isolated RAAs were found in 50 fetuses, and double aortic arches (DAAs) were recognized in eight other cases. The postnatal cohort consisted of 44 newborns with RAAs and eight with DAAs (two were lost to follow-up, and four pregnancies were terminated). Postnatal echocardiography confirmed the prenatal diagnosis of RAA in 41 of 45 children, and four were found to have DAAs. Three of seven fetuses diagnosed prenatally as having DAAs were found to have only RAAs. Fourteen fetuses underwent karyotyping; two had 22q11 deletion and two had 47xxy. Eleven infants (21%) had respiratory symptoms, eight with DAAs, one with RAA, mirror-image head and neck vessels, and two with RAAs and aberrant left subclavian arteries. Surgery was indicated in all symptomatic patients except one, whose symptoms resolved. One asymptomatic patient underwent operation for significant compression of the trachea.

CONCLUSIONS

RAA on fetal ultrasonography may indicate vascular and chromosomal abnormalities that may complicate postnatal management. When RAA is identified, fetal karyotype analysis (including the integrity of chromosome 22) is warranted. RAA may herald an occult DAA and may be a clue to a tight vascular ring. Hence, it seems essential to conduct a careful postnatal evaluation of fetuses with RAAs on prenatal ultrasound.