The multiform sonographic spectrum of arterial duct in right aortic arch

Abstract

To study the different characteristics of arterial duct (AD) in a series of prenatally detected right aortic arch (RAA). Out of 832 congenital heart diseases (CHD) referred to a tertiary center, 98 cases had RAA. Based on anatomical landmarks we identified 7 types of AD: type 1 left-sided, transverse; type 2 left-sided, vertical; type 3 from the underside of aortic arch (AA), vertical; type 4 right-sided, mirror-image “V”, transverse; type 5 right-sided, “H” shaped, transverse; type 6 bilateral; type 7 absent or unidentifiable. For each type of AD the incidence of associated major CHD was calculated and chi-square test was applied to verify the null hypothesis with significance level of p < 0.05. Type 1 occurred in 43% of cases including 4 with CHD and no cases with pulmonary outflow obstruction (POO). Symptoms of vascular ring were present in 41% of survivors. Type 2, 3 and 7 AD were associated with tetralogy of Fallot (TOF) or equivalents. No type 5 AD with CHD had POO and 3 isolated cases had asymptomatic hypoplasia of left pulmonary artery (LPA). Two type 6 AD had disconnection of LPA. Type 1 occurred more often as an isolated finding (p < 0.001), whereas types 2 (p = 0.0026), 3 (p = 0.0045), 4 (p = 0.0325) and 7 (p = 0.0001) were frequently associated with major CHD. In RAA, type 1 (U-shaped) is usually an isolated finding (p < 0.001) which includes all symptomatic vascular rings. POO is always present when the AD is vertical or absent but not when it lies on a transverse plane. Bilateral AD is rare and brings the risk of functionary loss of left lung if not identified.