Cerebroplacental hemodynamics in fetuses with transposition of the great arteries and usefulness in predicting neonatal condition

ObjectivesLiterature on cerebroplacental hemodynamics in fetuses with transposition of the great arteries (TGA) is scarce and provides conflicting results regarding the presence of a brain-sparing effect. The aims of this study were to examine Doppler parameters in the middle cerebral artery (MCA) and umbilical artery (UA) in a large cohort of fetuses with TGA, and to assess their possible utility in predicting the need for urgent balloon atrial septostomy (BAS) in the neonate.MethodsThis was a retrospective observational study of fetuses diagnosed with TGA between 2008 and 2022 and an age-matched cohort of normal fetuses, conducted in a single tertiary fetal cardiology center. Medical records and echocardiographic examinations were reviewed to collect demographic, sonographic and follow-up data. Selected Doppler parameters were compared between fetuses with TGA and normal fetuses, as well as between TGA fetuses with and those without an associated ventricular septal defect (VSD), to assess the impact of this congenital heart defect on cerebroplacental circulation. Additionally, Doppler indices in patients with a restrictive foramen ovale (FO) were analyzed to identify potential predictors of the need for urgent BAS.ResultsA total of 541 examinations of 159 fetuses with TGA performed between 19 and 40 weeks' gestation and 1300 examinations of 1215 age-matched normal fetuses were included in the study. MCA pulsatility index (PI) and UA-PI followed expected trends throughout pregnancy, with slightly higher values observed in TGA fetuses, albeit within the limits for the normal population. Cerebroplacental ratio (CPR) values were similar in normal and TGA fetuses. The presence of a small VSD did not have a clinically significant impact on Doppler parameters. Peak systolic velocity (PSV) in the MCA increased gradually after 35 weeks' gestation, especially in fetuses that did not develop restriction of the FO after birth. MCA-PSV values below 1.16 multiples of the median measured at 38 weeks or later predicted the need for urgent BAS with 81.4% sensitivity and 52.4% specificity.ConclusionsMCA-PI, UA-PI and CPR values in fetuses with TGA usually fall within normal limits throughout pregnancy. The presence of a small VSD does not affect the Doppler parameters significantly. MCA-PSV increases in TGA fetuses after 35 weeks, and its value measured at the last prenatal examination (ideally after 37 weeks) may serve as an additional predictive factor for the need for urgent BAS. & COPY; 2023 International Society of Ultrasound in Obstetrics and Gynecology.