Prenatal diagnosis of right aortic arch: associated findings, pregnancy outcome, and clinical significance of vascular rings.

OBJECTIVES: To analyze the characteristics and clinical implications of right aortic arch (RAA) detected in fetal life.

METHODS: Retrospective study of all cases of RAA diagnosed prenatally in high-risk patients who underwent fetal echocardiography between 2000 and 2007.

RESULTS: There were 48 RAA; 18 had vascular ring (Group 1), including 15 RAA with aberrant left subclavian artery and 3 double aortic arch, and 30 had not vascular ring (Group 2), all RAA with mirror-image branching. The prenatal diagnosis was confirmed in 94%. In Group 1 most fetuses had normal heart (89%), and none had 22q11 deletion. There were 16 live births and all infants but one are asymptomatic (mean follow-up of 31 months). In Group 2 almost all fetuses had congenital heart defects (CHDs) (97%), and five were chromosomally abnormal (17%), including four 22q11 deleted. The 1-year survival rate was 69%, which was significantly higher in Group 1 (89% vs 57%, p < 0.05).

CONCLUSIONS: RAA can be accurately diagnosed by fetal echocardiography. The outlook for these patients largely depends on the presence of associated defects, mainly CHDs, and their severity. If isolated, aortic arch anomalies are asymptomatic vascular variants in most cases. This information is important to assist parental counseling in pregnancy.