Methods
Twenty-two fetuses with DAA, 8 cases of which with hypoplastic left arch
and 2 cases of which with very hypoplasia of the distal left arch, and
65 fetuses with RAA-MB prenatally diagnosed with post-natal or autopsy
findings confirmed from our database of 27652 fetuses were analyzed
retrospectively in our center from October 2015 to October 2019.
Clinical data and prenatal echocardiographic features of the DAA and
RAA-MB were collected. The study design was approved by the ethics
review board of our hospital. Fetal autopsy following the termination of
the pregnancy was performed with the consent of the parents. Informed
consent was unnecessary for the other cases, as this is a retrospective
study.
Inclusion criteria: the cases confirmed by postnatal or autopsy
findings, clear three-vessel-trachea view, and a visible color in the
Doppler image of the first branch of the right aortic arch. Exclusion
criteria: the angle of the first branch of the RAA cannot be measured
due to the invisible beginning part of the first branch of the RAA.
All the fetal echocardiographic examinations were performed by a
physician with over 5 years of experience in our maternal-fetal medicine
consultation center, based on the guidelines previously
published.5-7 All fetal echocardiographs were obtained
using a Voluson E8/E10 equipped with a 2D/3D probe of 2- to 8-MHz (GE
Healthcare, Zipf, Austria).
The angle between the right aortic arch and its first branch was
measured by color Doppler imaging (Figure. 1) on the 3VT view. In the
DAA, the angle between the proximal parts of the two arches was
measured, while in the RAA-MB, the angle between the RAA and the left
brachiocephalic artery was measured.
Two observers completed the measurements of angles of the DAA and RAA
with mirror branches. They were blinded to the final results. Twenty
cases were randomly selected to measure the angle to determine the
internal and interval variability of the observers by using the same
view. The interval between the two measurements for the same observer
was two weeks.