Innovations in transcatheter interventions for hypoplastic left heart syndrome and borderline left heart structures from fetal to neonatal life: current evidence and systematic review of recent advances (2016-2025).

Alongside advances in surgical and medical care, catheter-based interventions have reshaped the care of fetuses and neonates with hypoplastic left heart syndrome (HLHS) or borderline left heart structures over the last decades. These interventions include fetal aortic valvuloplasty (FAV), fetal and neonatal atrial septal interventions, the hybrid Stage-1 procedure (HS1P), and the emerging total transcatheter Stage-1 procedure (TTS1P). We summarize the current evidence on catheter-based interventions for HLHS and borderline left heart structures from fetal to neonatal life and systematically review recent advances (2016-2025). Among 361 studies identified (+ 12 manually), 68 were included (17: FAV, 4: fetal/neonatal atrial septal interventions, 39: HS1P, 8: TTS1P). FAV outcomes have continued to improve over time, confirming its potential to alter the progression to HLHS in selected patients. In patients with HLHS and an intact or severely restrictive atrial septum, fetal and neonatal atrial septal interventions can mitigate severe perinatal respiratory failure; however, outcomes in this population remain significantly burdened by underlying lung disease. In the neonatal period, both HS1P and TTS1P offer less invasive alternatives to the surgical Stage-1 procedure, spanning both univentricular and biventricular recruitment pathways. HS1P offers a cardiopulmonary bypass-sparing strategy with favorable outcomes in experienced centers. TTS1P further reduces invasiveness by eliminating both sternotomy and cardiopulmonary bypass and has demonstrated promising early results. As techniques, devices, and patient selection continue to evolve, further research will be critical to establish the most appropriate application of each approach and to align prenatal and postnatal management pathways to optimize outcomes.