Prenatal Right Aortic Arch and Double Arch: A Population-based Study of Vascular Rings

Background and aims: Introduction of the three-vessel-trachea-view to the second trimester Fetal Anomaly Screening Programme increased detection of right (RAA) and double (DAA) aortic arch. Aim was to investigate incidence, associations and medium-term outcome of RAA/DAA. Methods: Retrospective, population-based, multi-centre, observational study of fetuses diagnosed with RAA/DAA between 1/4/2015–31/3/2019. All cardiology units in England, Scotland and Wales participated. Fetuses with major congenital heart disease were excluded. Results: 1046 fetuses were diagnosed with RAA (n=898, 85.9%) or DAA (n=141, 13.5%), un-categorized in seven (0.6%). Estimated incidence of RAA and DAA was 17.98 and 4.58 per 10,000 pregnancies screened/year (0.23%). 940 cases (89.9%) were isolated, with prenatal extra-cardiac anomaly (ECA) and/or minor cardiac difference in the remainder. Genetic results were abnormal in 80/1046 (7.6%): 22q11.2 microdeletion (n=28, 35%). Prenatal ECAs increased the risk of genetic anomaly, RR 3.39 (95%CI 1.89-5.73, p<0.0001). 986 (94.3%) were liveborn, five died postnatally from unrelated problems. Mean follow-up 4.1 years (SD 1.4), symptoms of tracheoesophageal compression found in 278/986 (28.2%). Vascular ring relief performed in 234/986 liveborn (23.7%) with no deaths. There was variation in management pathways. Surgery was performed in 74.6% with DAA, 24.4% with RAA-left arterial duct (LAD)-aberrant-left subclavian artery (ALSA); median age at surgery was 5.29 months (IQR: 2.99-11.26 months) and 12.62 months (IQR: 8.68-17.32 months) respectively (p<0.0001). Conclusions: Incidence of RAA/DAA is higher than previously reported. Genetic anomaly is identified in at least 7.6%, particularly in the presence of ECA. Liveborn with DAA have earlier, and more surgical intervention compared to those with RAA-LAD-ALSA.