OP08.07: <i>In utero</i> stenting of the atrial septum in fetuses with hypoplastic left heart syndrome with highly restrictive or intact atrial septum: a single‐centre experience

Fetuses with hypoplastic left heart syndrome (HLHS) and highly restrictive atrial septum (AS) carry a significant risk for profound cyanosis after birth. In the setting of an intact AS without presence of a decompressing vessel, the evolution of a “nutmeg” lung (arterialisation of pulmonary veins and severe pulmonary lymphangiectasia) leads to almost 100% mortality in these patients. In utero interventions on the AS were introduced to reduce the risk of urgent procedures postnatally and to prevent the evolution of severe secondary lung damage. Here we present a single-centre experience of in utero stenting. The local fetal cardiac intervention database was queried for this study. Patient charts were reviewed retrospectively. For in utero stenting of the atrial septum 3.5x9mm Prokinetic Energy (Biotronic®) stents were used and introduced via an 18G cannula. Between 2000 and 2024 249 fetal cardiac interventions (FCI) were performed in 198 fetuses. Fifteen procedures on the AS were carried out in 12 fetuses with overall 10 AS stentings performed in 10 fetuses with HLHS at a mean gestational age of 33+2 weeks (25+3-38+3)-three of them late stentings to avoid EXIT procedures. Overall, one stenting was not successful due to dislocation of the stent and 3 were with only limited hemodynamic effects due to suboptimal final stent position. There was 1 late procedure related death. In all successful cases there was improvement of pulmonary vein Doppler and none of the late stented patients required an EXIT procedure. Eight fetuses were liveborn after successful stenting, with 3 dying in the neonatal period due to persistent lung damage (all with suboptimal stent position). In utero stenting of the atrial septum is technically feasible but challenging. Ideal positioning of the stent is crucial to enable effective decompression of the left atrium. In selected cases late in utero stenting can be used as an alternative to EXIT procedures.