Association Between Fenestration Size and Early Postoperative Outcomes Following Fontan Surgery: A Five-Year Single-Center Experience in Vietnam

Background: Fenestration is a well-established modification of the Fontan procedure intended to reduce systemic venous pressure and limit early postoperative complications. However, the optimal fenestration diameter that balances clinical benefits with systemic oxygenation remains uncertain. This study aimed to evaluate the association between fenestration size and early outcomes following extracardiac Fontan surgery. Methods: We retrospectively analyzed pediatric patients who underwent fenestrated extracardiac Fontan surgery at Cho Ray Hospital between January 2020 and March 2025. Fenestration diameters ranged from 4 to 8 mm. Postoperative complications were categorized as pulmonary, cardiovascular, infectious, renal, or mortality events. Continuous outcomes included postoperative pleural drainage duration, intensive care unit stay, hospital stay, and perioperative change in peripheral arterial oxygen saturation (SpO2). Correlation analyses were employed to assess the associations between fenestration size and outcomes. Results: Twenty patients (median age: 5 years; 70% male) were included. Pulmonary complications were most common (85%), with pneumonia and pleural effusion observed in 65% of cases. Fenestration size was not associated with overall complication incidence; however, cardiovascular complications differed between groups (p = 0.045), without a linear trend (p for trend = 0.271). Oxygenation improved significantly perioperatively (median SpO2 increased from 76% to 86%, mean change: 10.6%; p = 0.001). Fenestration size correlated inversely with perioperative SpO2 change (ρ = –0.75; p < 0.001), while larger fenestrations correlated with shorter pleural drainage (ρ = –0.71; p = 0.001) and reduced hospital stay (ρ = –0.59, p = 0.012). Conclusion: Fenestration significantly impacts early outcomes after a Fontan operation. Larger fenestrations promoted faster recovery, with shorter pleural drainage and hospital stays, but conferred a smaller oxygenation benefit. Individualized fenestration sizing may help optimize early outcomes in pediatric Fontan patients.