EXPLANATION


Fetal echocardiography has been an important component in the identification and management of CHD for some time. In 2023, the American Society of Echocardiography updated their guidelines on when and how expectant women should get comprehensive fetal echocardiography. Typically, fetal echocardiography is indicated when the standard 5-view fetal scan performed at 20 weeks’ gestation is abnormal or if the expectant mother has a significant family history or medical comorbidities that would place their fetus at higher risk for CHD.


In 1999, Bonnet and al published a report comparing outcomes of neonates with d-Transposition of the Great Arteries (d-TGA) who underwent prenatal diagnosis to those who presented post-natally. They showed patients with prenatal echocardiogram had better pre- and post-operative mortality, and were less likely to present in shock, metabolic acidosis and need mechanical ventilation¹. This study is often cited in contemporary literature. However, more recent studies have failed to clearly demonstrate mortality benefits to prenatal diagnosis across the braoder spectrum of CHD. A meta-analysis from China in 2015², which included 1171 patients from 8 studies, looked at the effect of prenatal diagnosis on delivery variables, preoperative management and perioperative mortality in patients with major CHD, which included double-outlet right ventricle, d-TGA and, hypoplastic left heart syndrome (HLHS) and critical left-sided obstructive lesions among others. They found that patients who had prenatal diagnosis underwent surgical procedures almost 3 days earlier as well as improved pre- and post-operative mortality but only in the TGA patients after subgroup analysis. This reflects that, with prenatal diagnosis, perinatal and operative plans could be devised before birth. In contrast, patients who present post-natally may be in critical condition at diagnosis, thus requiring time for stabilization and surgical planning.


A recent study from Georgia looked at the ability for fetal echocardiography to predict the level of care and interventions necessary for 747 neonates with CHD³. The level of care was assigned based on the risk of hemodynamic compromise in the neonatal period and need for early intervention, such as presence of hydrops, or need for balloon atrial septostomy in HLHS or d-TGA. They found the level of care attributed to patients predicted interventions in 92% of the cohort. In lower level of care patients, ie those with none to minimal risk of hemodynamic compromise, need for unplanned intervention was rare. They also noted patients who did not undergo the predicted course were higher-risk neonates who required less intensive care than predicted by fetal echo. Interesingly, children with d-TGA and HLHS had a higher rate of unexpected events, which is attributed to the imperfect nature of fetal echocardiogram.


Thus, it has been demonstrated that identifying fetal CHD can lead to improved neonatal morbidity after delivery and during the perioperative period,¹ especially with regards to mobilization of resources and the prompt initiation of resuscitative measures and performance of emergent atrial septostomy for stabilization of the neonate with CHD. However, evidence of improved overall patient mortality when their CHD lesion was identified on fetal echocardiography is less conclusive. Of the possible answers for the question, only d-TGA has evidence supporting reduced mortality associated with identification on fetal echocardiography.¹ Other lesions such as interrupted aortic arch (IAA) or complete atrioventricular canal (CAVC), while complex, have not been shown to have improved mortality with prenatal diagnosis. It is worth noting that in utero diagnosis of CHD allows for possible fetal cardiac intervention in lesions such as aortic stenosis, evolving HLHS and PA/IVS,⁴ as well as for risk stratification for early intervention in a context of resources allocation³.


REFERENCES


1- Bonnet, D., et al., Detection of transposition of the great arteries in fetuses reduces neonatal morbidity and mortality. Circulation, 1999. 99(7): p. 916-8.

2- Li, Y.F., et al., Efficacy of prenatal diagnosis of major congenital heart disease on perinatal management and perioperative mortality: a meta-analysis. World J Pediatr, 2016. 12(3): p. 298-307

3- Ro SS, Milligan I, Kreeger J, et al. Utilizing Fetal Echocardiography to Risk Stratify and Predict Neonatal Outcomes in Fetuses Diagnosed with Congenital Heart Disease. Am J Perinatol. 2025;42(3):369-378. doi:10.1055/s-0044-1788718

4- Prosnitz, A.R., et al., Early hemodynamic changes after fetal aortic stenosis valvuloplasty predict biventricular circulation at birth. Prenat Diagn, 2018. 38(4): p. 286-292.