Systemic Oxygen Saturation and Coagulation Factor Abnormalities Before and After the Fontan Procedure

Coagulation factor abnormalities are believed to predispose to increased risk for thromboembolism after the Fontan procedure. Recent data, however, suggest that coagulation abnormalities may precede the operation. This study determined coagulation factor abnormalities in patients with single-ventricle congenital heart defects before the Fontan procedure and compared the findings with age-matched post-Fontan patients and control subjects. Liver function, coagulation factor levels, and pulse oximetry readings were determined in 11 pre-Fontan patients aged 9.3 ± 5.6 years. The results were compared with those of 11 age-matched post-Fontan patients, at 9.1 ± 2.4 years after the Fontan procedure, and 11 age-matched controls by simple analysis of variance and post hoc Tukey’s test. Liver function was normal in patients before and after surgery apart from mildly elevated bilirubin levels in post-Fontan patients (p = 0.027). When compared with controls, pre-Fontan patients had significantly lower levels of protein C; protein S; antithrombin III; and factors II, V, VII, and X and longer prothrombin times (all with p <0.05). When compared with post-Fontan patients, pre-Fontan patients had similarly lower levels of free protein S (p <0.001), protein C (p = 0.06), and antithrombin III (p = 0.001). Systemic oxygen saturation correlated positively with the levels of anticoagulants (protein C, protein S, antithrombin III) and procoagulants (factors II, V, VII, and X) (all with p <0.05, r = 0.33 to 0.61). In conclusion, the findings suggest that coagulation factor abnormalities precede the Fontan procedure and tend to normalize after the operation, relating perhaps to improved systemic oxygenation.