Optimization of the optimal anticoagulation strategy during cardiopulmonary bypass for neonates with congenital heart disease: a single-center randomized controlled study

Background During cardiopulmonary bypass (CPB) for neonatal congenital heart surgery, heparin dosing is critical due to the immature coagulation system in neonates. Current practices often rely on adult-based anticoagulation strategies, but no consensus exists for optimal heparin dosing. This study aims to optimize heparin dosing, improving surgical safety and minimizing postoperative complications. Methods This two-phase study explores heparin dosing strategies. Phase 1 is a pilot trial to determine the optimal heparin dose for neonatal CPB. Phase 2 compares this optimal dose with the traditional 400 U/kg dose in a randomized controlled trial. Coagulation markers, bleeding volume, and clinical outcomes, including blood product use, are analyzed. Results In Phase 1, 30 neonates were randomized into three groups. Higher heparin doses (500 U/kg and 600 U/kg) showed higher ACT achievement rates, but no significant differences were found in bleeding volume, transfusion, or thrombin generation. In Phase 2, 76 neonates (37 in each group) were analyzed. The experimental group (600 U/kg) achieved significantly higher ACT rates (89.19% vs. 43.24%, P < 0.001) and shorter CPB initiation times (31.61 ± 8.99 min vs. 37.00 ± 10.48 min, P = 0.021). Post-CPB, the experimental group had significantly lower F1+2 levels [3.53 (2.80, 4.24) nmol/L vs 5.77 (3.79, 9.52) nmol/L, P < 0.001] and lower thrombin generation [0.31 (0.09, 0.89) nmol/L vs 3.32 (0.95, 6.70) nmol/L, P < 0.001]. APTT was significantly longer in the experimental group [63.35 (56.83, 71.85) s vs 54.60 (48.45, 70.45) s, P = 0.001], as was TT [19.15 (17.83, 20.38) s vs 18.40 (17.65, 19.75) s, P = 0.01]. D-Dimer was significantly lower in the experimental group [1.94 (1.25, 4.69) µg/mL vs 6.19 (2.74, 12.24) µg/mL, P = 0.002], as was FDP [4.81 (3.19, 17.54) µg/mL vs 10.63 (6.53, 26.91) µg/mL, P = 0.004]. DIC scores at 24 and 48 hours were lower in the experimental group (P = 0.031, P = 0.026). There were no significant differences in blood loss, blood product usage, or other adverse outcomes between the groups. Conclusion An initial heparin dose of 600 U/kg optimizes anticoagulation during CPB in neonates without increasing bleeding risk. This strategy improves ACT achievement, reduces thrombin generation, and lowers coagulation markers such as F1+2, D-Dimer, and FDP. It also shortens surgery preparation time, providing a safer, more effective anticoagulation approach. These findings support the establishment of guidelines for heparin dosing in neonatal CPB.