## 3 Results  
### Clinical Characteristics of the Groups  
In our study, the gender distribution was similar between the three groups (69% males in the Fontan group, 52% males in the Glenn group and 53% males in the Control group), with no statistical difference between the groups: Fontan vs. Control \(p\) = 0.4, Glenn vs. Control \(p\) = 0.97. Regarding the age distribution, the Fontan group consisted of older children (mean age 10 years) compared to the Glenn group (mean age 5 years). There was no significant difference in the age of the children included in the Fontan or Glenn group vs. Controls (\(p\) = 0.27 and 0.059 respectively). In the Fontan group, 8 patients had a univentricular left heart and 5 patients had a univentricular right heart, whereas in the Glenn group, 9 patients had a univentricular left heart and 12 patients had a univentricular right heart. In total, 9 out of the total patients with the Fontan operation had fenestration and all Fontan patients had an extracardiac tunnel. On abdominal echography, we found that hepatomegaly was present both in the Fontan group (38% of patients) and in the Glenn group (33% of patients), whereas no children included in the control group had hepatomegaly. Regarding Fontan patients, we found three cases (23%) with splenomegaly, whereas only one patient from the Glenn group presented an enlarged spleen (4%). The children included in the Fontan and Glenn groups had a lower mean BMI than the healthy children included in the Control group (15.33 kg/m\({}^{2}\) vs. 17.7 kg/m\({}^{2}\), \(p\) = 0.13 and 15.71 kg/m\({}^{2}\) vs. 17.7 kg/m\({}^{2}\), \(p\) = 0.14). The patients in the Glenn group had a much lower mean oxygen saturation (82.8%) than the Fontan group (93.8%) and the control group (98.7%). The baseline characteristics of the groups are included in Table 1. Figure 1 highlights the included patients and the main investigations. \begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Patient Characteristics**} & **Fontan** & **Glenn** & **Control** \\  & **N/Mean \(\pm\) SD** & **N/Mean \(\pm\) SD** & **N/Mean \(\pm\) SD** \\ \hline
**Demographics** & **n = 13** & **n = 21** & **n = 32** \\ Male/Female & 9/4 & 11/10 & 17/15 \\ Age (years) & 10 \(\pm\) 3.83 & 5.24 \(\pm\) 4.7 & 8.39 \(\pm\) 5.48 \\ Time interval since operation (months) & 50 \(\pm\) 27 & 25.2 \(\pm\) 36 & - \\ \hline
**Ultrasound evaluation** & & & \\ Univentricular left heart & 8 & 9 & - \\ Univentricular right heart & 5 & 12 & - \\ Extracardiac tunnel & 13 & & - \\ Fenestration & 9 & & - \\ Hepatomegaly & 5 & 7 & 0 \\ Splenomegaly & 3 & 1 & 0 \\ \hline
**Clinical characteristics** & & & \\ BMI (kg/m\({}^{2}\)) & 15.33 \(\pm\) 2.67 & 15.71 \(\pm\) 3.59 & 17.70 \(\pm\) 4.01 \\ SO\({}_{2}\) (\%) & 93.8 \(\pm\) 2.39 & 82.8 \(\pm\) 5.6 & 98.7 \(\pm\) 0.2 \\ \hline \end{tabular}
\end{table} 
Table 1: Clinical characteristics of the groups. In terms of laboratory results, when comparing the [PERSON] group to the controls, we found statistically significant differences for Fibrotest, Actitest, APRI, ALT, GGT, ApoA1, and the thrombocyte count (Table 2, Figure 3). We used the Mann-Whitney test for nonparametric values, unpaired, two tails. The Fibrotest investigation revealed a degree of liver fibrosis in 9 patients: F1 fibrosis in 1 patient, F2 fibrosis in 7 patients and F3 fibrosis in 1 patient, whereas 4 patients had F0 fibrosis. The Actitest investigation revealed A1 necro-inflammatory activity in 3 patients and A0 in 9 Fontan patients. We obtained a positive correlation between the time after the Fontan operation and ALT (r = 0.5, \(p\) = 0.04) and Actitest (r = 0.57, \(p\) = 0.03)--Figure 4. We also found a positive correlation between V\({}_{\text{median}}\) determined by SWE and ALT (r = 0.7, \(p\) = 0.009) and also Actitest (r = 0.63, \(p\) = 0.02). We found no significant correlation between the time after the Fontan operation and V\({}_{\text{median}}\) determined by SWE (r = 0.53, \(p\) = 0.07) or E\({}_{\text{median}}\) determined by SWE (r = 0.07), respectively.