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Predicting the Need for Urgent BAS in Fetal d-TGA

•Posted inObstetrics and Gynaecology

Managing d-transposition of the great arteries (d-TGA) remains a critical challenge for neonatologists and pediatric cardiologists in India and globally. Newborns often face life-threatening hypoxia if they lack adequate intracardiac shunting. Consequently, predicting urgent neonatal BAS (balloon atrial septostomy) before delivery is vital for planning immediate postnatal care. A recent study explored how combining fetal echocardiography with cardiac magnetic resonance imaging (CMR) and acute maternal hyperoxygenation (AMH) improves this prediction.

Identifying Predictors through Fetal Echocardiography

Echocardiography serves as the primary tool for assessing fetal cardiac anatomy. Specifically, clinicians focus on the foramen ovale (FO) and the morphology of the atrial septum. A restrictive foramen ovale or a hypermobile septum often signals inadequate mixing after birth. Furthermore, Doppler studies help evaluate blood flow patterns that might indicate impending neonatal distress. However, traditional ultrasound sometimes lacks the sensitivity needed for precise risk stratification. Therefore, medical teams are increasingly looking toward advanced imaging modalities to refine their diagnostic accuracy.

The Added Value of CMR and AMH

Cardiac magnetic resonance imaging (CMR) provides detailed insights into fetal hemodynamics and oxygenation levels. During the study, researchers utilized CMR to quantify vascular oxygen saturation and fetal weight. Additionally, they performed acute maternal hyperoxygenation (AMH) testing as a diagnostic aid. This provocative test measures how the fetal circulation responds to increased oxygen levels. If the pulmonary vasculature fails to react normally, the newborn may face a higher risk of severe hypoxia. Consequently, these physiological responses provide a clearer picture than anatomy alone.

Enhanced Strategies for Predicting Urgent Neonatal BAS

The prospective study monitored 34 newborns with d-TGA and an intact or nearly intact ventricular septum. Notably, researchers found that 68% of these infants required a balloon atrial septostomy. Within this group, twelve cases were classified as urgent, occurring within the first three hours of life. By analyzing predelivery imaging features, the team identified markers that effectively assist in predicting urgent neonatal BAS. These findings underscore the importance of specialized imaging in high-risk pregnancies. Moreover, such data allows specialized centers to streamline delivery planning and immediate neonatal intervention.

Frequently Asked Questions

Q1: Why is predicting the need for a balloon atrial septostomy (BAS) important in d-TGA?

Predicting the need for BAS is critical because newborns with d-TGA often require immediate intervention to ensure adequate oxygen mixing. Early identification allows medical teams to prepare for emergency procedures within the first few hours of life, significantly reducing the risk of permanent organ damage from hypoxia.

Q2: How does acute maternal hyperoxygenation help in prenatal assessment?

Acute maternal hyperoxygenation acts as a provocative test to evaluate fetal pulmonary vascular reactivity. It helps clinicians understand how the fetal circulatory system might respond to the transition at birth. Consequently, it identifies those at highest risk for severe postnatal hypoxia that may not be evident on standard ultrasound.

References

  1. Jaeggi E et al. Role of predelivery fetal echocardiography, cardiac magnetic resonance imaging and acute maternal hyperoxygenation in predicting urgency of neonatal balloon atrial septostomy in fetal d-transposition of the great arteries. Ultrasound Obstet Gynecol. 2026 Mar 05. doi: 10.1002/uog.70200. PMID: 41784038.
  2. Słodki M et al. New method to predict need for Rashkind procedure in fetuses with dextro-transposition of the great arteries. Ultrasound Obstet Gynecol. 2018 Apr;51(4):531-536. doi: 10.1002/uog.17469.
  3. Vigneswaran TV et al. Acute Maternal Hyperoxygenation to Predict Hypoxia and Need for Emergency Intervention in Fetuses With Transposition of the Great Arteries: A Pilot Study. J Am Soc Echocardiogr. 2024. doi: 10.1016/j.echo.2024.12.011.