Fetal interrupted aortic arch: 2D-4D echocardiographic assessment, associations and outcome.

OBJECTIVES.: To analyze fetal 2D echocardiographic characteristics of interruption of the aortic arch (IAA) and its different types, and to explore whether the use of 4D ultrasound with B-flow imaging and spatio-temporal image correlation (STIC) can improve prenatal diagnostic accuracy. Associations and outcome were also determined. METHODS.: The study comprised 12 IAA fetuses examined exclusively by 2D conventional echocardiography, and a group of 10 additional cases initially identified by conventional echocardiography and examined further by 4D ultrasound with B-flow imaging and STIC. Postnatal follow-up was available for all. Karyotype and FISH analysis for the DiGeorge critical region were performed in all cases. RESULTS.: Twenty-two cases of isolated IAA (15 type B and 7 type A) were detected among 2520 cases of fetal congenital heart defects (CHD). In 7/15 type B cases, right subclavian artery (SA) arose anomalously. 2D echocardiography failed to individuate the type of IAA in only two cases and the aberrant right subclavian artery (ARSA) in 5/7 cases. B-flow imaging and STIC successfully identified IAA types in all 10 cases examined and clearly visualized the origin and the course of ARSA, including the cervical ones. FISH detected 22q11.2 microdeletion in 11 of 22 fetuses (ten type B cases and an unusual association with type A in one case). Fetal/neonatal outcome was as follows: eight terminations of pregnancy, one intrauterine death, and four post-operative deaths in the neonatal period. The remaining nine neonates were alive after surgery at a mean follow up time of 58 months (range, 4 months-13 years). CONCLUSION: Our report confirms the feasibility of the prenatal characterization of IAA and its different types, based on 2D echocardiographic examination albeit with some limitations in the thorough assessment. 4D ultrasound with B-flow imaging and STIC is apparently able to facilitate and detail the anatomical features of the IAA types, including visualization of the neck vessels, thus supplying additional information with respect to 2D sonography. As for the known association with the microdeletion 22q11.2, our data indicate that that type A and type B are distinct entities confirming a close association of 22q11.2 microdeletion only with IAA type B. Copyright (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.