Technical Advances and Outcomes of Fetal Atrial Septal Intervention for Restrictive or Intact Atrial Septum

Abstract

Background: Infants with hypoplastic left heart syndrome with severely restrictive or intact atrial septum (R/IAS) have low survival. In-utero creation of an atrial septal communication has been reported, with high complication rates.

Methods: We performed a retrospective cohort study of fetuses with hypoplastic left heart syndrome, double outlet right ventricle with mitral stenosis/atresia, or mitral valve dysplasia and R/IAS from 2012 to 2024 who underwent evaluation for fetal atrial septal intervention (FASI). Excluding those with comorbidities limiting candidacy, discharge survival and overall survival were compared between (1) those undergoing and not undergoing FASI, and (2) those undergoing technically successful FASI (TS-FASI) and all others.

Results: Of 60 fetuses with R/IAS, 18 were considered extremely high risk and excluded from analysis. Among the remaining 42, 25 underwent FASI and 17 did not, with no significant baseline echocardiographic differences. FASI was technically successful in 18 cases, with 13 survivors (6 post-Glenn, 6 post-Fontan, 1 post-Ross). In the 7 unsuccessful FASIs, there were 5 peri-procedural deaths and 1 fetal demise that occurred post-FASI. Technical success rates improved from 58% (first 12) to 85% (last 13). Of 20 FASI patients with fetal magnetic resonance imaging, 15 (75%) had nutmeg lung; of the 9 with nutmeg lung and post-TS-FASI fetal magnetic resonance imaging, 8 improved. Survival to discharge and overall survival were 52% in the FASI group versus 29% in the non-FASI group (P=0.147 and log-rank P=0.376, respectively). When comparing TS-FASI to all others, survival was higher (72% versus 21% for discharge and overall survival, P=0.001 and log-rank P<0.001, respectively). All TS-FASI survivors with catheterization data (11/13) had pulmonary vascular resistance <3 Woods units before Glenn/Fontan.

Conclusions: In our cohort, fetuses with R/IAS post-TS-FASI had significantly higher discharge and overall survival rates compared with all other fetuses with R/IAS. Nutmeg lung improved in the majority of TS-FASI cases with post-FASI imaging.

Keywords: aortic valve stenosis; atrial septum; fetal death; hypoplastic left heart syndrome; lung; mitral valve insufficiency; vascularresistance.