Maternal Hyperoxygenation Testing in Fetuses with Hypoplastic Left-Heart Syndrome: Association with Postnatal Atrial Septal Restriction

Abstract

<b><i>Introduction:</i></b> In fetuses with hypoplastic left-heart syndrome (HLHS), maternal hyperoxygenation (MHO) may aid risk stratification. We hypothesized that pulmonary vein (Pvein) velocity time integral (VTI) change with MHO would more reliably identify neonates who undergo emergent atrial septoplasty (EAS) than changes in pulmonary arterial pulsatility index (PA PI). <b><i>Methods:</i></b> Fetuses with HLHS who underwent MHO testing at our institution between 2014 and 2019 were identified. Data were reviewed in a blinded, retrospective manner. Pvein VTI ratio (prograde:retrograde) was calculated. The primary outcome was neonatal EAS. <b><i>Results:</i></b> Twenty-seven HLHS fetuses underwent MHO, and 5 (19%) underwent EAS. Without MHO, a Pvein VTI ratio <3 conferred 60% sensitivity and 100% specificity for EAS. With MHO, a Pvein VTI ratio <6.5 conferred 100% sensitivity and specificity. For an intermediate group of fetuses with a baseline Pvein VTI ratio 3–7, the ratio decrease with MHO conferred 100% sensitivity and specificity. Compared to the Pvein VTI ratio, PA PI was less accurate in identifying EAS neonates. <b><i>Discussion/Conclusion:</i></b> Addition of MHO appears to improve the diagnostic ability of the Pvein VTI ratio to identify HLHS fetuses who undergo EAS. The Pvein VTI ratio change may more accurately identify fetuses who undergo EAS than change in PA PI and has less interobserver variability.

Maternal hyperoxygenation during pregnancy as a tool in fetal disease diagnosis and treatment

“…Higher Pvein VTI ratios after MHO in the non‐EAS group were observed. The authors concluded that these findings would be more accurate and easier to obtain for a fetal cardiologist endeavoring to distinguish the high‐risk subgroup of HLHS fetuses with RAS than the change in PA proposed by Szwast A. et al 2,21 …”

“…39 MHO was proposed as a method to improve the detection of RAS Higher Pvein VTI ratios after MHO in the non-EAS group were observed. The authors concluded that these findings would be more accurate and easier to obtain for a fetal cardiologist endeavoring to distinguish the high-risk subgroup of HLHS fetuses with RAS than the change in PA proposed by Szwast A. et al 2,21 Maternal hyperoxygenation (MHO) as a test seems to be very useful for investigating the hemodynamics of fetuses with CHD and for predicting and stratifying the severity of the malformation. The reaction to oxygen and improvement of cardiovascular parameters in the early third trimester raises the question of long-term oxygen administration to improve outcomes in selected types of CHD (Table 2).…”

Hypoplastic Left Heart Syndrome: Is There a Role for Fetal Therapy?

“…The hemodynamic effects of MH have been shown to be useful in prenatal diagnosis and counseling. Acute MH in fetuses with left heart hypoplasia was specifically studied in patients with HLHS and restrictive or intact atrial septum (62,66,71,72). Severe restriction or an intact atrial septum significantly aggravates the overall prognosis in fetuses with hypoplastic left heart syndrome as described above.…”

“…Similar findings were reported in a study by Enzensberger et al, also showing that there was no response to acute MH in fetuses with HLHS and RAS (66). Mardy et al (72), however, investigated the effect of acute MH on pulmonary venous return analyzing the pulmonary vein prograde/retrograde VTI ratio (48,(73)(74)(75) with regard to emergent postnatal intervention. Different pulmonary vein flow patterns with increasing restriction of the atrial septum are shown in Figure 5.…”

“…Different pulmonary vein flow patterns with increasing restriction of the atrial septum are shown in Figure 5. Emergent postnatal intervention could be predicted with 100% sensitivity and 100% specificity by using the following classification: Fetuses with a baseline Pvein VTI ratio <3 were ascribed to the emergent intervention group as well as fetuses with a Pvein VTI ratio between 3 and 7 with a decrease from baseline to MH (72). The branch pulmonary artery PI showed less sensitivity and specificity in the same study (72).…”