Transcatheter completion of the extracardiac Fontan provides a minimally invasive option for selected children with single-ventricle physiology who have undergone staged preparation at the time of the bidirectional cavopulmonary connection.

We performed a retrospective single-centre review of consecutive patients treated between 2022 and 2025. Candidate selection, cross-sectional imaging, diagnostic catheterisation, procedural steps, early recovery, and follow-up outcomes were collected.

Five patients underwent transcatheter completion at a median age of 7 years (range 4–17). The interval between the preparatory operation and catheter procedure was 7 months (range 6–9). Median procedure time was 140 minutes (range 120–180). The ICU stay was 2 days (range 1–3), and the total hospital stay was 5 days (range 4–6). Minimal pleural effusions occurred in four patients, none requiring drainage. At a median follow-up of 28 months (range 4–36), all patients were clinically stable; resting oxygen saturation was 96% (range 94% to 97%). One late-presenting patient had biochemical evidence consistent with protein-losing enteropathy but remained asymptomatic without targeted therapy. No thromboembolic events occurred.

In a programme that couples surgical preparation with later catheter-based completion, the extracardiac Fontan can be performed safely and effectively in carefully selected candidates, with rapid recovery and stable mid-term clinical status. Larger studies are needed to define long-term outcomes and comparative effectiveness versus surgical completion.