D-Transposition of the great arteries with restrictive foramen ovale in the fetus: the dilemma of predicting the need for postnatal urgent balloon atrial septostomy

OBJECTIVE

Restrictive foramen ovale (FO) in dextro-transposition of the great arteries (d-TGA) with intact ventricular septum may lead to severe life-threatening hypoxia within the first hours of life, making urgent balloon atrial septostomy (BAS) inevitable. Reliable prenatal prediction of restrictive FO is crucial in these cases. However, current prenatal echocardiographic markers show low predictive value, and prenatal prediction often fails with fatal consequences for a subset of newborns. In this study, we described our experience and aimed to identify reliable predictive markers for BAS.

METHODS

We included 45 fetuses with isolated d-TGA that were diagnosed and delivered between 2010 and 2022 in two large German tertiary referral centers. Inclusion criteria were the availability of former prenatal ultrasound reports, of stored echocardiographic videos and still images, which had to be obtained within the last 14 days prior to delivery and that were of sufficient quality for retrospective re-analysis. Cardiac parameters were retrospectively assessed and their predictive value was evaluated.

RESULTS

Among the 45 included fetuses with d-TGA, 22 neonates had restrictive FO postnatally and required urgent BAS within the first 24 h of life. In contrast, 23 neonates had normal FO anatomy, but 4 of them unexpectedly showed inadequate interatrial mixing despite their normal FO anatomy, rapidly developed hypoxia and also required urgent BAS ('bad mixer'). Overall, 26 (58%) neonates required urgent BAS, whereas 19 (42%) achieved good O2 saturation and did not undergo urgent BAS. In the former prenatal ultrasound reports, restrictive FO with subsequent urgent BAS was correctly predicted in 11 of 22 cases (50% sensitivity), whereas a normal FO anatomy was correctly predicted in 19 of 23 cases (83% specificity). After current re-analysis of the stored videos and images, we identified three highly significant markers for restrictive FO: a FO diameter < 7 mm (p < 0.01), a fixed (p = 0.035) and a hypermobile (p = 0.014) FO flap. The maximum systolic flow velocities in the pulmonary veins were also significantly increased in restrictive FO (p = 0.021), but no cut-off value to reliably predict restrictive FO could be identified. If the above markers are applied, all 22 cases with restrictive FO and all 23 cases with normal FO anatomy could correctly be predicted (100% positive predictive value). Correct prediction of urgent BAS also succeeded in all 22 cases with restrictive FO (100% PPV), but naturally failed in 4 of the 23 cases with correctly predicted normal FO ('bad mixer') (82.6% negative predictive value).

CONCLUSION

Precise assessment of FO size and FO flap motility allows a reliable prenatal prediction of both restrictive and normal FO anatomy postnatally. Prediction of likelihood of urgent BAS also succeeds reliably in all fetuses with restrictive FO, but identification of the small subset of fetuses that also requires urgent BAS despite their normal FO anatomy fails, because the ability of sufficient postnatal interatrial mixing cannot be predicted prenatally. Therefore, all fetuses with prenatally diagnosed d-TGA should always be delivered in a tertiary center with cardiac catheter stand-by, allowing BAS within the first 24 h after birth, regardless of their predicted FO anatomy.

Clinical features and echocardiographic findings of isolated foramen ovale restriction in foetuses

Isolated restrictive foramen ovale (rFO) without complex heart defects is a rare pathology. There may be difficulties in managing this situation, which can lead to right heart enlargement, tricuspid regurgitation and hydrops findings in the foetus. We conducted a retrospective analysis of 8451 foetuses. 7883 (93.2%) had a structurally normal heart or minor heart disease, 18 (0.22%) of which had a diagnosis of isolated rFO. Nine patients with neonatal echocardiographic examination were included in the study. In 8 (88.8%) patients, it was stated that a decision to give birth should be made at the time of presentation. Evaluating postpartum echocardiographic examinations, 7 (77.7%) patients had normal or minor defects. The decision of delivery made at the right time during follow-up is critical to determine the prognosis.IMPACT STATEMENTWhat is already known on this subject? The data about the prenatal diagnosis of isolated rFO is limited.What the results of this study add? We conducted a retrospective analysis of 8451 foetuses. 7883 (93.2%) foetuses had a structurally normal heart or minor heart disease, 18 (0.22%) of which had a diagnosis of rFO. Nıne patients with foetal and postnatal follow-up and echocardiographic findings were examined in the study. The group's median gestational age at admission was 35.0 weeks (range: 27.0-39.0 weeks). The delivery decision was made in 8 (88.8%) patients at the time of admission. Evaluating postpartum echocardiographic examinations, 7 (77.7%) patients had normal or minor defects. Additionally, one patient was diagnosed with cardiomyopathy, and the other patient was diagnosed with functional pulmonary atresia. No death occurred in any foetus during follow-up.What the implications are of these findings for clinical practice and/or further research? Isolated rFO, a rare condition in the foetus, is generally well-tolerated in foetal life. However, the right heart enlargement, tricuspid regurgitation, or hydrops findings can be seen in patients. The decision of delivery made at the right time during follow-up is critical to determine the prognosis.