Small Intestinal Bacterial Overgrowth and Immunological Disturbances in Fontan- Associated Enteropathy

Small Intestinal Bacterial Overgrowth and Immunological Disturbances in Fontan- Associated Enteropathy | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Small Intestinal Bacterial Overgrowth and Immunological Disturbances in Fontan- Associated Enteropathy Anna Socha-Banasiak, Anna Mazurek-Kula, Natalia Nawara-Węgrzyn, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7826456/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background Gastrointestinal complications, including protein-losing enteropathy (PLE) and Fontan-Associated Liver Disease (FALD) are common in the group of patients after Fontan procedure. However, the data concerned the Small Intestinal Bacterial Overgrowth (SIBO) occurrence in this group of patients are lacking. The general aim of this study was to determinate the SIBO occurrence in the group of the patients after Fontan surgery. Moreover, we focused to compare the enteropathy, immunological disturbances and SIBO diagnosis depending on the type of Fontan procedure. Methods This was a cross-sectional observational study (years 2021–2024) including patients after Fontan procedure (study group) and healthy subjects (control group) aged 5–18 years from 2 polish pediatric centers. In all subjects’ laboratory tests including blood counts and biochemical parameters were performed. Additionally, in the study group the immunoglobulin serum concentrations and peripheral lymphocytes subpopulation were examined. Lactulose Hydrogen Breath Test (LHBT) was used to SIBO recognition. Enteropathy was diagnosed based on clinical and laboratory features. Results There were no differences in SIBO occurrence between study and control groups. In the group with PLE (16.2%) immunological deficiencies were found more often than in the group without enteropathy (IgG (72.73% vs. 3.51%; p < 0.00), IgA (36.36% vs. 10.53%; p = 0.04), CD4 (100% vs. 56.14%; p = 0.00), CD19 (45.45% vs. 14.04%; p = 0.02). SIBO was recognized more frequently in the group after intracardiac Fontan (ICF) than extracardiac Fontan (ECF) communication (p = 0.01) but was not associated with immunological disturbances. Conclusions The SIBO occurrence in dependence of the type of Fontan procedure may be due to differences in the gut perfusion between ICF and ECF groups, that require confirmation in future research. Small Intestinal Bacterial Overgrowth Fontan operation enteropathy Figures Figure 1 Figure 2 Background The Fontan operation is palliative procedure dedicated for patients with functional single ventricle congenital heart lesions. The outcomes of the surgery have improved with 30 years survival rates reaching up to 85% [ 1 ]. Initially, the operation was made in the form of intracardiac Fontan (ICF) connection. However, ICF was associated with hypertrophy of right atrium and subsequently to supraventricular arrhythmias as well as problems of increased venous pressure, and obstruction of the systemic venous to pulmonary arterial pathway [ 2 ]. Those complications led to the development of extracardiac Fontan (ECF) technique offering improved hemodynamics and a lower incidence of arrhythmias [ 3 ]. On the other hand, recent data suggests that ECF may be associated with faster development of cirrhosis [ 4 ]. Despite high survival rate after Fontan procedure, some gastrointestinal complications, including protein-losing enteropathy (PLE) and Fontan-Associated Liver Disease (FALD) remain severe and potentially life-threatening [ 5 , 6 ]. The above-mentioned complications are mainly caused by organ congestion related to high central venous pressure (CVP), chronic heart failure from low cardiac output, and hypoxia, all of which may contribute over time to multiorgan dysfunction [ 7 ]. The PLE affects 5–15% patients following the Fontan procedure. PLE is characterized by the loss of serum proteins into the gut lumen, leading to chronic diarrhea, general abdominal discomfort and peripheral edema [ 8 ]. In the literature, the diagnostic criteria for PLE are inconsistent, they generally include clinical symptoms, hypoalbuminemia and augmented enteric protein loss (elevation of the fecal α-1 antitrypsin level) [ 8 , 9 ]. Several factors contribute to the development of PLE including impaired lymphatic drainage due to elevated CVP, obstruction of the thoracic duct, increased mesenteric resistance, lymphatic congestion and reduced mesenteric flow, all leading to distention of hepatoduodenal lymphatic channels and intestinal mucosa damage [ 10 , 11 ]. These pathological processes lead to enteric loss of albumin, immunoglobulins, lymphocytes and clotting factors which manifest clinically as chronic diarrhea, peripheral edema, ascites and immune deficiency [ 10 ]. Recent data showed that PLE in Fontan patients is associated with significant alterations of T cell differentiation promoted by several miRNA controlled immunological pathways [ 12 ]. All patients after Fontan surgery develop Fontan-associated liver disease (FALD), a distinctive type of congestive hepatopathy primarily triggered by increased CVP and decreased cardiac output [ 13 ]. The circulation disturbances cause intrahepatic nitric oxide concentration that in turn promotes hepatocellular necrosis, atrophy, and fibrinogenic responses [ 14 ]. Additionally, increased lymph angiogenesis in the liver contributes to dilatation of the hepatic sinusoids leading to poor lymph drainage. These factors promote liver dysfunction, tissue inflammation, and fibrosis [ 15 ]. Considering the intestinal and general immune dysregulation, enteropathy, circulation disturbances and liver disfunction, all of which are potential factors leading to gastrointestinal microbial imbalances [ 16 ], the Small Intestinal Bacterial Overgrowth (SIBO) in the patients after Fontan surgery may be suspected. The SIBO is defined as an excessive proliferation of bacteria (> 10 3 –10 5 CFU/mL) in the small intestine, alteration in the bacterial composition, or both. The microbiota of SIBO patients is mainly characterized by overgrowth of colonic bacteria, including coliform bacteria and anaerobes, which contribute to carbohydrates fermentation, decreased vitamin and micronutrient absorption and subsequent mucosal inflammation [ 16 ]. To date, only one abstract in the literature has reported the SIBO occurrence in this patient population [ 17 ]. Methods The primary aim of this study was to examine the incidence of SIBO in patients after Fontan surgery and healthy subjects. Additionally, we aimed to compare enteropathy, immunological disturbances and SIBO prevalence between the patients after ICF and ECF procedures. Patients: This was a cross-sectional observational study included patients aged 5–18 years who had undergone the Fontan operation (study group) and were hospitalized between 2021 and 2024 at either the Department of Gastroenterology, Allergology and Paediatrics, Polish Mother’s Memorial Hospital – Research Institute in Lodz or the Department of Paediatric Cardiology, Jagiellonian University Medical College, Cracow, Poland. All subjects were under the care of local cardiology and/or gastroenterology outpatients’ clinic. Children and adolescents without chronic gastrological and cardiological history and lack of contraindications to participate were included as a convenience sample (control group). The exclusion criteria included: hospitalization due to acute conditions (trauma, infection, exacerbation of chronic disease), chronic inflammatory gastrointestinal or kidney diseases, endocrine disorders, malignancy and/or use of antibiotics or other medications that could influence the Lactulose Hydrogen Breath Test (LHBT) results (described below). A detailed cardiovascular history of the examined children was collected, including type of congenital heart defect (hypoplastic left heart syndrome, hypoplastic right heart syndrome), presence of fenestration, type of Fontan operation (ICF, ECF) and age at the time of surgery. All patients underwent anthropometric measurements (body weight [kg], height [cm]). Body mass index (BMI) was calculated using the formula weight/height 2 and was subsequently converted into Z-scores and percentiles based on national growth charts [ 18 , 19 ]. Additionally, during clinical examinations the presence of diarrhea, edema and ascites occurrence was noted. Lactulose Hydrogen Breath Test Hydrogen breath test was used as a noninvasive test for detecting SIBO occurrence (Gastrolyzer gastro plus, Bedfont Scientific, England). All subjects fasted for 8 to 12 hours prior to the test. A 4-week interval between antibiotic, laxatives, probiotics and prokinetics was required [ 20 , 21 , 22 ]. Foods rich in malabsorbed carbohydrates (fresh vegetables and fruits) were excluded from diet for 3 days before test. After brushing the teeth, the baseline breath samples were collected (a hydrogen level of ≤ 10 ppm was required to proceed with the test). The LHBT was then conducted using 10 g of lactulose. After consuming the dissolved lactulose substrate, breath samples were collected every 15 min for the next 2 hours. During the testing, patients were not allowed to sleep, eat, drink, or engage in any vigorous activity. The SIBO was diagnosed as if there was a rise in hydrogen of ≥ 20 ppm above the baseline value within 90 minutes [ 21 ]. Blood sampling and laboratory analyses Venous blood samples were collected after 12 h of fasting into standard vacuum tubes. Laboratory tests including blood morphology, biochemical parameters and lymphocyte subpopulation were performed. The following parameters and laboratory methods were used: potassium and sodium levels (ion-selective electrode method), total protein concentrations (endpoint method), albumin (bromocresol green method), AST, ALT, GGT (the immunoenzymatic assay according to the International Federation of Clinical Chemistry method (IFCC)), IgA, IgG, IgM concentrations (IFCC turbidimetric method), NT-proBNP concentration (electrochemiluminescence immunoassay). All biochemical analyses were performed on following equipment: Beckman Coulter: DxC 700AU and Cobas Pro e801 according to the manufacturer's recommendations. INR was exanimated with coagulometric method (ACL550, Werfen). Peripheral blood lymphocyte subpopulations were determined by flow cytometry using commercially available kits (BD Multitest 6-Color TBNK with BD Trucount Tubes). Analysis was performed on a Becton Dickinson BD FACSCanto II flow cytometer. Results were expressed as absolute values ​​and percentages for CD3+, CD4+, CD8 + T lymphocytes, CD19 B lymphocytes and CD56 + CD16 + NK cell populations. Fecal alpha-1-antitrypsin level was measured with ELISA method, and the results were expressed in µg/g (norm range < 268). Protein-losing enteropathy PLE was diagnosed based on evidence of increased enteric protein loss, indicated by elevated fecal alpha-1-antitrypsin levels above the normal reference range, subclinical or associated with hypoalbuminemia (serum albumin < 3.5 g/dL) and at least one of the following clinical signs: peripheral edema, abdominal distension or discomfort, diarrhea, or the presence of serous effusions (ascites, pleural, or pericardial effusions) [ 23 ]. Statistical analysis Categorical variables were reported as counts and percentages. Continuous variables were summarized using the median and interquartile (IQR), along with lower and upper quartile. Comparisons between categorical variables were conducted using the chi-squared test (χ²) with Yates’ continuity correction or Fisher’s exact test, as appropriate. Continuous variables between two independent groups were compared using the nonparametric Mann–Whitney U test. Associations between continuous variables were assessed using Spearman’s rank correlation coefficient. Missing data was imputed using the mean value of the respective variable. To adjust for potential confounding factors, generalized linear models (GLMs) were applied. A two-sided p-value < 0.05 was considered statistically significant. All analyses were performed using RStudio (version 4.4.1). Results A total of 88 children and adolescents (51,13% males) with a median age of 12.6 years were enrolled in the study including 68 subjects after Fontan surgery and 20 controls. The anthropometric and biochemical features of the studied group are presented in Table 1 . The results of the LHBT showed no statistically significant differences in SIBO occurrence between study and control groups (n = 22 (32.35%) vs. n = 9 (45%); p = 0.44). Table 1 Characteristic of the study population Variable p Study group (n = 68) Control group (n = 20) Body weight [kg] 45.44 (28.5-56.24) 40.85 (27.4-51.75) 0.41 Height [cm] 156.5 (131.5–166) 147.5 (128-165.5) 0.78 BMI [kg/m2] 18.03 (16.23–21.79) 17.32 (14.21–20.25) 0.24 Body weight [z-score] -0.38 (-1.12–0.44) -0.5 (-1.21–0.32) 0.91 Height [z-score] -0.86 (-1.57–0.34) -0.06 (-0.48–0.69) 0.00 BMI [z-score] -0.05 (-0.92–0.71) -0.54 (-1.55–0.31) 0.29 RBC [10^6/uL] 5.06 (4.81–5.38) 4.72 (4.32–4.81) < 0.00 Hb [g/dL] 14.55 (13.8–15.5) 13.6 (12.2–14.2) 0.00 Hct [%] 41.9 (39.5–45.42) 38.2 (34.4–39.8) 0.00 PLT [10^3/µL] 200 (156.5–263.75) 275 (250–308) 0.00 WBC [10^3/uL] 6.07 (4.78–7.57) 5.87 (5.44–7.55) 0.68 Sodium [mmol/L] 138 (137–139) 139 (138–140) 0.18 Potassium [mmol/L] 4.31 (4.08–4.6) 4.1 (4.09–4.2) 0.04 Calcium [mmol/L] 2.45 (2.29–2.55) 2.5 (2.38–2.52) 0.75 INR 1.3 (1.2–1.4) 1.1 (1.1–1.2) < 0.00 ALT [U/L] 37.15 (30.75–44) 25 (22.8–32) < 0.00 ALT [U/L] 27 (21.75–32.25) 14 (10–16) < 0.00 GGT [U/L] 47 (33–62) 13.5 (10.75–15.25) < 0.00 Values are expressed as median (IQR) BMI - Body Mass Index, RBC – Red Blood Count, Hb – Hemoglobin, Hct- Hematocrit, PLT – platelets, WBC – White Blood Count, INR - International Normalized Ratio, ALT- Alanine aminotransferase, AST - Aspartate aminotransferase, GGT - Gamma-glutamyltransferase. Protein-losing enteropathy and immunological status PLE was confirmed in 11 patients (16.2%) from the study group. There was no statistically significant difference in the age [months] at which the Fontan procedure was performed between patients with and without PLE (36 (30.5–41.0) vs. 48 (35.0–58.0); p = 0.07). Clinical examination revealed no significant difference in the occurrence of ascites between the groups (p > 0.05). However, peripheral edema was significantly more common in the PLE group (6/11; 54.55%) compared to the non-PLE group (3/57; 5.26%; p = 0.00). Patients in the PLE group demonstrated significantly lower serum albumin and IgG concentrations, reduced total lymphocyte count and subpopulation of CD3, CD4 and CD8 (p < 0.05). The analysis of laboratory parameters in the studied groups is presented in Table 2 . Table 2 Comparison of Laboratory Parameters Between Patients with and without Protein-losing Enteropathy (PLE) Variable p PLE (n = 11) Without PLE (n = 57) AST [U/L] 40.20 (30.60–45.0) 37.10 (30.90–43.0) 0.758 ALT [U/L] 32.0 (28.0–40.0) 25.0 (21.0–30.0) 0.069 GGT [U/L] 55.0 (29.0–88.0) 47.0 (35.0-58.73) 0.594 NT-proBNP [pg/mL] 135.60 (108.20-310.55) 141 (68–271) 0.565 INR 1.20 (1.15–1.35) 1.30 (1.20–1.40) 0.093 Albumin [g/L] 3.44 (2.58–3.84) 4.70 (4.50–4.90) < 0.000 TP [g/L] 5.65 (4.23–5.98) 7.20 (6.84–7.50) < 0.000 RBC [10^6/uL] 5.18 (4.96–5.54) 5.01 (4.80–5.35) 0.159 Hb [g/dL] 14.80 (14.15–15.15) 14.50 (13.80–15.50) 0.745 Hct [%] 42.50 (41.10–45.05) 41.70 (39.50–45) 0.617 PLT [10^3/µL] 234 (181–275.50) 197 (152–262) 0.185 WBC [10^3/uL] 6.44 (4.58–7.13) 5.89 (4.80–7.59) 0.907 Lymphocytes [10^3/uL] 0.90 (0.66–1.10) 1.40 (1.03–2.20) 0.001 Sodium [mmol/l] 137.0 (135.50–139.0) 138.0 (137.0–139.0) 0.255 Potassium [mmol/L] 4.0 (3.87–4.12) 4.39 (4.10–4.60) 0.006 Calcium [mmol/L] 2.13 (2.05–2.27) 2.47 (2.37–2.58) < 0.000 IgG [g/L] 3.83 (2.55–6.12) 9.97 (8.39–11.85) 0.999 IgA [g/L] 0.96 (0.50–1.28) 1.30 (0.99–1.67) 0.052 CD3 [10^3/ul] 0.40 (0.23–0.44) 0.76 (0.58–0.93) < 0.000 CD4 [10^3/ul] 0.18 (0.12–0.24) 0.47 (0.34–0.60) < 0.000 CD8 [10^3/ul] 0.16 (0.07–0.17) 0.24 (0.18–0.32) 0.000 CD19 [10^3/ul] 0.29 (0.16–0.43) 0.33 (0.25–0.39) 0.576 NK [10^3/ul] 0.22 (0.16–0.41) 0.23 (0.14–0.35) 0.658 Values are expressed as median (IQR) ALT - Alanine aminotransferase, AST - Aspartate aminotransferase, GGT - Gamma-glutamyltransferase, INR - International Normalized Ratio, TP – total protein, RBC – Red Blood Count, Hct – Hematocrit, Hb – Hemoglobin, PLT – platelets, WBC – White Blood Count, INR - International Normalized Ratio, IgG – Immunoglobulin G, IgM – Immunoglobulin M, IgA – Immunoglobulin A, NK- Natural Killers. Deficiencies in immunoglobulin and lymphocyte subpopulations were more frequently observed in the PLE group than in those without PLE. Specifically, IgG deficiency was found in 8 patients (72.73%) with PLE vs. 2 patients (3.51%) without enteropathy (p < 0.00), IgA deficiency in 4 patients (36.36%) vs. 6 patients (10.53%, p = 0.04), CD4 deficiency in 11 patients (100%) vs. 32 patients (56.14%, p = 0.00), and CD19 deficiency in 5 patients (45.45%) vs. 8 patients (14.04%, p = 0.02). The relationship between immunological variables and the diagnosis of PLE is shown in Fig. 1 . There was no statistically significant difference in the occurrence of SIBO between patients with and without PLE (n = 3 (27.27%) vs. n = 19 (33.33%); p > 0.99). No significant associations were found between lymphopenia and liver function parameters including PLT count, INR, albumin level as well as AST, ALT and GGT activity (p > 0.05) (Fig. 2 ). Type of Fontan operation The analysis of medical history showed that 24 patients (35,3%) underwent ICF while 44 subjects (64,7%) had ECF procedures. The PLE (n = 7 (63.64%) vs. n = 4 (36.36%); p = 0.04) and hypoalbuminemia (n = 6 (25.0%) vs. n = 1 (2.27%); p = 0.00) were more frequently observed in the ICF group compared to the ECF procedure. Taking into account clinical symptoms, the peripheral edema (n = 7 (29.17%) vs. n = 2 (4.55%); p = 0.00) and ascites (n = 4 (16.67%) vs. n = 0; p = 0.01) were more frequently observed in the ICF group. Additionally, SIBO was more common in the ICF group (n = 13 (54.17%) vs. n = 9 (20.45%); p = 0.00). Initial laboratory analysis suggested immunological differences related to the type of Fontan procedure. However, due to significant difference in age at the time of operation (ICF procedure 33.50 months (27.50–40.25) vs. ECF 54 months (41.75–67); p < 0.00) a statistical adjustment was performed. After adjusting for age no significant immunological differences remained between the groups (Table 3 , Table 4 ). Nevertheless, SIBO was more frequent in patients after ICF compared to those after ECF procedure (p = 0.01) (Table 3 ). Table 3 Analysis of clinical and immunological variables according to Fontan procedure type. Variable p p adjusted with age at surgery ICF (n = 24) ECF (n = 44) Enteropathy Yes/No 7 (63.64)/17 (29.82) 4 (36.36)/40 (70.18) 0.04 0.20 SIBO Yes/No 13 (54.17)/9 (20.45) 9 (20.45)/35 (79.55) 0.00 0.01 Ascites Yes/No 4 (16.67)/20 (83.33) 0/44 (100) 0.01 - Peripheral oedema Yes/No 7 (29.17)/17 (70.83) 2 (4.55%)/42 (95.45%) 0.00 0.01 Hypoalbuminaemia Yes/No 6 (25)/18 (75) 1 (2.27%)/43 (97.73%) 0.00 0.06 Lymphocytes Deficit/Norm 5 (20.83)/19 (79.17) 16 (36.36%)/28 (63.64%) 0.27 0.51 NK Deficit/Norm 4 (16.67)/20 (83.33%) 8 (18.18%)/36 (81.82%) > 0.99 0.39 CD19 Deficit/Norm 4 (16.67%)/20 (83.33%) 9 (20.45%)/35 (79.55%) > 0.99 0.37 CD8 Deficit/Norm 21 (87.50%)/3 (12.50%) 33 (75%)/11 (25%) 0.34 0.23 CD4 Deficit/Norm 19 (79.17%)/5 (20.83%) 24 (54.55%)/20 (45.45%) 0.06 0.27 CD3 Deficit/Norm 23 (95.83%)/1 (4.17%) 32 (72.73%)/12 (27.27%) 0.02 0.05 IgA Deficit/Norm 6 (25%)/18 (75%) 4 (9.09%)/40 (90.91%) 0.14 0.20 IgM Deficit/Norm 1 (4.17%)/23 (95.83%) 8 (18.18%)/36 (81.82%) 0.14 0.26 IgG Deficit/Norm 5 (20.83%)/19 (79.17%) 5 (11.36%)/39 (88.64%) 0.30 0.56 Values are expressed as n (%). ICF- intracardiac Fontan, ECF – extracardiac Fontan, SIBO – small intestinal bacterial overgrowth, NK- Natural Killers, IgG – Immunoglobulin G, IgM – Immunoglobulin M, IgA – Immunoglobulin A. Table 4 Comparison of immunological parameters by type of Fontan procedure. Variable p p adjusted for age at surgery time ICF (n = 24) ECF (n = 44) IgG [g/l] 8.26 (7.10–10.33) 9.98 (7.67–11.46) 0.19 0.36 IgM [g/l] 0.76 (0.56–1.04) 0.86 (0.68–1.11) 0.42 0.52 IgA [g/l] 1.14 (0.88–1.48) 1.39 (0.96–1.74) 0.12 0.36 CD3 [10^3/µL] 0.54 (0.42–0.74) 0.78 (0.58–0.97) 0.01 0.06 CD4 [10^3/µL] 0.33 (0.24–0.45) 0.48 (0.32–0.61) 0.00 0.05 CD8 [10^3/µL] 0.19 (0.15–0.23) 0.25 (0.16–0.33) 0.08 0.21 CD19 [10^3/µL] 0.34 (0.26–0.42) 0.32 (0.20–0.42) 0.68 0.45 NK [10^3/µL] 0.24 (0.15–0.36) 0.22 (0.14–0.35) 0.71 0.51 Values are expressed as median (IQR) ICF- intracardiac Fontan, ECF – extracardiac Fontan, IgG – Immunoglobulin G, IgM – Immunoglobulin M, IgA – Immunoglobulin A, NK- Natural Killers. Discussion Although recent studies have highlighted the role of gut dysbiosis in cardiovascular diseases [ 24 ], gastrointestinal disorders in patients after Fontan surgery remain poorly understood. Hepatic dysfunction and PLE, which commonly occur in this population, may significantly affect gut microbiome colonization and composition. The literature data on this topic are scarce [ 25 , 26 ]. One case-control study involving patients after Fontan procedure indicated that gut microbiota dysbiosis is connected with active PLE. Moreover, changes in the bacterial composition of the gut microbiota and decreased diversity may be associated with the severity of PLE [ 25 ]. Wang et al. showed that alteration in the microbial composition and biodiversity may serve as distinctive characteristics of patients who have undergone Fontan circulation [ 26 ]. To the best of our knowledge, no previous studies have investigated the relationship between SIBO and the Fontan procedure. However, it is well established that altered gut perfusion and circulatory disturbances are associated with a high prevalence of SIBO in patients with cardiovascular diseases [ 27 , 28 ]. In our study, we found no significant differences in the incidence of SIBO between the study and control groups, nor between patients after Fontan procedure with and without PLE. On the other hand, the results of LHBT were significantly associated with the type of Fontan procedure regardless of the age of the surgery. Despite the absence of differences in PLE and immunological disturbances between ECF and ICF groups after adjusting for age at the time of surgery, the explanation for increase of SIBO incidence after ICF procedure remains unclear. This phenomenon may be due to different hemodynamic parameters in both groups which could influence intestinal blood supply. Abdominal organs are especially vulnerable to alterations in hemodynamics as hepatic blood flow is mostly dependent on portal venous circulation, which relies on a low-pressure gradient between the portal and hepatic veins [ 29 ]. Consequently, elevated systemic venous pressure affects the hemodynamic balance impairing both liver and gut function [ 29 ]. The results of Kisamori et al. showed that ECF is associated with conduit obstruction accelerating liver fibrosis and cirrhosis [ 4 ]. This observation suggests that differences in surgical technique may lead to distinct hemodynamics potentially influencing gastrointestinal function. However, this thesis requires further investigation. Our results related to lymphocyte count and immunological parameters are similar to observation reported by other authors. Lymphopenia is common in patients after Fontan operation; however the etiology of this phenomenon remains poorly understood [ 23 ]. Some authors associate the occurrence of lymphopenia not only with PLE but also with FALD. It has previously been shown that lymphopenia is common in adult Fontan patients and is associated with markers of portal hypertension [ 4 ]. Moreover, lymphopenia with thrombocytopenia may serve as a simple primary non-invasive diagnostic tool for early risk stratification of FALD onset [ 30 ]. In the past leucopenia in cirrhosis was attributed to suppressed in vitro leucocyte proliferation. More recent data showed that attenuation in circulating lymphocytes may result from peripheral (liver) recruitment. Liver samples from Fontan patients demonstrated upregulation of endothelial cells and total lymphocytes, especially of NK and T-cells. The authors concluded that hepatic changes in adolescent Fontan patients are triggered by T-cells which are contributing to the early development and possible progression of FALD [ 30 ]. In our study we found no significant correlation between hepatic parameters and PLE. Those results are probably due to the fact that the study included only children - in whom all mechanisms responsible for lymphopenia were not fully yet developed. In our study the PLE was associated with a significant lower lymphocyte count compared to subjects without enteropathy. This finding is consistent with previous observation and results from the lymphocyte loss in the gastrointestinal tract by abnormal intraluminal lymphatic drainage [ 12 , 31 ]. Prior studies have shown that enteropathy is connected with loss of particular lymphocyte subpopulation, however the data remain inconsistent [ 31 , 32 ]. In our cohort, patients with PLE showed decreased count of CD3, CD4 and CD8 cells, however only CD4 and CD19 lymphocytes were below the normal range. Our findings support the hypothesis that the immune system is involved in the development and maintenance of PLE. The differences in peripheral lymphocyte count may result from different half-lives of lymphocyte subpopulation [ 33 ]. In the patients with PLE several authors showed a selective loss of CD4 lymphocytes and slightly reduced levels of CD8 lymphocytes resulting in decreased CD4/CD8 ratio [ 8 , 31 ]. Magdo et al. suggested that this is effect of selective transport of CD4 cells into the lymphatics, supported by the finding of a significantly higher CD4:CD8 ratio in body fluid (such as chylothorax or chyloperitoneal fluid) compared to the blood [ 31 ]. On the other hand, more recent data indicate that immunological disturbances in this group of patients may be related to significant alterations in T cell differentiation, that is dysregulated by several miRNA controlling immunological pathways [ 12 ]. There are potential limitations of our study. First, including the pioneering data on SIBO occurrence in patients after ICF and ECF procedures, we did not include hemodynamic measurements or MRI results, which could have provided further insight into observed findings. Second, the diagnosis of SIBO was based on the LHBT results rather than the duodenal aspiration that may influence reliability. However, LHBT was chosen to avoid exposing the patients to an invasive procedure. Conclusions Our results confirmed the correlation between PLE occurrence and immunological disturbances in patients after Fontan procedure. SIBO occurrence was associated with the type of Fontan operation but no with PLE, lymphopenia and lymphocyte subpopulation intestinal lost. These findings may reflect differences in gut perfusion between ICF and ECF group, however this hypothesis requires confirmation through studies including hemodynamic parameters and abdominal MRI scans. Abbreviations Iintracardiac Fontan (ICF) Extracardiac Fontan (ECF) Protein-losing enteropathy (PLE) Fontan-Associated Liver Disease (FALD) Central venous pressure (CVP) Fontan-associated liver disease (FALD), Small Intestinal Bacterial Overgrowth (SIBO) Lactulose Hydrogen Breath Test (LHBT) Body mass index (BMI) International Federation of Clinical Chemistry method (IFCC) Interquartile (IQR) Declarations Ethics approval and consent to participate This study followed the standards of the Declaration of Helsinki and was approved by Bioethics Committee of the Polish Mothers Memorial Hospital - Research Institute (PMMH-RI 42/2021) and Jagiellonian University Bioethics Committee (1072.6120.141.2022), respectively. All parents and children ≥16 years old provided written informed consent before participation. Consent for publication Not applicable Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests No conflict of interest, financial or other, exists. Funding The study was funded by the Polish Ministry of Science & Higher Education, Polish Mother’s Memorial Hospital – Research Institute - Internal Grant no 3GW/II/2021 and Jagiellonian University CM Internal Grant no N41/DBS/000905. Authors' contributions Anna Socha-Banasiak - conception and design of the work, analysis and interpretation of data, writing the manuscript, tables and figures conception. Anna Mazurek-Kula - recruitment for the study, analysis and interpretation of data, final approval of the version to be published. Natalia Nawara-Węgrzyn - recruitment for the study, analysis and interpretation of data, final approval of the version to be published. Sebastian Góreczny - conception or design of the work, final approval of the version to be published. Katarzyna Kucharska - recruitment for the study, analysis and interpretation of data, statistical analysis, final approval of the version to be published. Elżbieta Czkwianianc - analysis and interpretation of data, final approval of the version to be published. Kinga Kowalska-Duplaga- analysis and interpretation of data, final approval of the version to be published. References Khairy P, Fernandes SM, Mayer JE, Jr. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation. 2008;117(01):85–92. doi: 10.1161/CIRCULATIONAHA.107.738559. Talwar S, Sengupta S, Choudhary SK. The intra-extracardiac Fontan: preliminary results. Indian J Thorac Cardiovasc Surg. 2020;36(3):193-198. doi: 10.1007/s12055-019-00862-7. Epub 2019 Oct 18. Talwar S, Divya A, Makhija N, Choudhary SK, Airan B. Immediate and early post-operative sequelae of off-pump total cavopulmonary connection. Indian J Thorac Cardiovasc Surg. 2018;34:468–75. Kisamori E, Venna A, Chaudhry HE, Desai M, Tongut A, Mehta R, et al. Alarming rate of liver cirrhosis after the small conduit extracardiac Fontan: A comparative analysis with the lateral tunnel. J Thorac Cardiovasc Surg. 2024;168(4):1221-1227.e1. doi: 10.1016/j.jtcvs.2024.04.013. Barracano R, Merola A, Fusco F, Scognamiglio G, Sarubbi B. Protein-losing enteropathy in Fontan circulation: Pathophysiology, outcome and treatment options of a complex condition. Int J Cardiol Congenit Heart Dis. 2022;7:100322. doi: 10.1016/j.ijcchd.2022.100322. Emamaullee J, Zaidi AN, Schiano T, Kahn J, Valentino PL, Hofer RE, et al. Fontan-Associated Liver Disease: Screening, Management, and Transplant Considerations. Circulation. 2020 Aug;142(6):591-604. doi: 10.1161/CIRCULATIONAHA.120.045597. Ohuchi H. Where Is the "Optimal" Fontan Hemodynamics? Korean Circ J. 2017;47(6):842-857. doi: 10.4070/kcj.2017.0105. Epub 2017 Sep 18. Koch A, Hofbeck M, Feistel H, Buheitel G, Singer H. Circumscribed intestinal protein loss with deficiency in CD4+ lymphocytes after the Fontan procedure. Eur J Pediatr 1999;158: 847–850. Thorne SA, Hooper J, Kemp M, Somerville J. Gastro-intestinal protein loss in late survivors of Fontan surgery and other congenital heart disease. Eur Heart J. 1998;19(3):514-20. doi: 10.1053/euhj.1997.0777. Blissett S, Kheiwa A, Mahadevan VS. Extracardiac manifestations of the Fontan circulation in adults: Beyond the liver. Int J Cardiol Congenit Heart Dis. 2022;8:100358. doi: 10.1016/j.ijcchd.2022.100358. Mohanakumar S, Telinius N, Kelly B. Morphology and function of the lymphatic vasculature in patients with a Fontan circulation. Circ Cardiovasc Imaging. 2019;12(04):e008074. doi: 10.1161/CIRCIMAGING.118.008074. Moosmann J, Toka O, Lukassen S, Ekici AB, Mackensen A, Völkl S, et al. Lymphocyte Immune Response and T Cell Differentiation in Fontan Patients with protein-losing enteropathy. Thorac Cardiovasc Surg. 2021;69(S 03):e10-e20. doi: 10.1055/s-0041-1723781. Epub 2021 Feb 19. de Lange C, Möller T, Hebelka H. Fontan-associated liver disease: Diagnosis, surveillance, and management. Front Pediatr. 2023;11:1100514. doi: 10.3389/fped.2023.1100514. Rychik J, Goldmuntz E. Invited commentary: the hunt for mechanistic origins of liver fibrosis in the Fontan circulation. World J Pediatr Congenit Heart Surg. 2021; 12(2):173–5. 10.1177/2150135121989974. Chung C, Iwakiri Y. The lymphatic vascular system in liver diseases: its role in ascites formation. Clin Mol Hepatol. 2013; 19(2):99–104. 10.3350/cmh.2013.19.2.99 Roszkowska P, Klimczak E, Ostrycharz E, Rączka A, Wojciechowska-Koszko I, Dybus A, et al. Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge. Biomedicines. 2024;12(5):1030. doi: 10.3390/biomedicines12051030. https://www.uni-kiel.de/aepc/2016/aepcHandouts/Handout_602.pdf. Kułaga Z, Grajda A, Gurzkowska B, Góźdź M, Wojtyło M, Swiąder A, et al. Polish 2012 growth references for preschool children. Eur J Pediatr. 2013;172(6):753–61. Kułaga Z, Różdżyńska-Świątkowska A, Grajda A, Gurzkowska B, Wojtyło M, Góźdź M, et al. Percentile charts for growth and nutritional status assessment in polish children and adolescents from birth to 18 year of age. Standrady Medyczne/Pediatria. 2015;12:119–35 Eisenmann A, Amann A, Said M, et al. Implementation and interpretation of hydrogen breath tests. J Breath Res 2008; 2: 046002 doi: 10.1088/1752-7155/2/4/046002. Pimentel M, Saad RJ, Long MD, et al. ACG clinical guideline: Small intestinal bacterial overgrowth. Am J Gastroenterol 2020;115(2):165–78. Cangemi DJ, Lacy BE, Wise J. Diagnosing Small Intestinal Bacterial Overgrowth: A Comparison of Lactulose Breath Tests to Small Bowel Aspirates. Dig Dis Sci. 2021;66(6):2042-2050. doi: 10.1007/s10620-020-06484-z. Alsaied T, Lubert AM, Goldberg DJ, Schumacher K, Rathod R, Katz DA, et al. Protein losing enteropathy after the Fontan operation. Int J Cardiol Congenit Heart Dis. 2022;7:100338. doi: 10.1016/j.ijcchd.2022.100338. Witkowski M., Weeks T L, Hazen, SL. Gut microbiota and cardiovascular disease. Circ. Res. 2000; 127, 553–570. doi: 10.1161/CIRCRESAHA.120.316242 Go K, Horiba K, Yamamoto H, Morimoto Y, Fukasawa Y, Ohashi N, et al. Dysbiosis of gut microbiota in patients with protein-losing enteropathy after the Fontan procedure. Int J Cardiol. 2024;396:131554. doi: 10.1016/j.ijcard.2023.131554. Wang K, Han L, Ma J, Fang Y, He Y, Liu X, et al. Gut microbiota community and metabolic profiles in direct total cavopulmonary connection and Fontan circulation: a cross-sectional study in the single center. Front Microbiol. 2025;16:1539046. doi: 10.3389/fmicb.2025.1539046. Fialho A, Fialho A, Kochhar G, Schenone AL, Thota P, McCullough AJ, et al. Association Between Small Intestinal Bacterial Overgrowth by Glucose Breath Test and Coronary Artery Disease. Dig Dis Sci. 2018;63(2):412-421. doi: 10.1007/s10620-017-4828-z. Song Y, Liu Y, Qi B, Cui X, Dong X, Wang Y, et al. Association of Small Intestinal Bacterial Overgrowth With Heart Failure and Its Prediction for Short-Term Outcomes. J Am Heart Assoc. 2021;10(7):e015292. doi: 10.1161/JAHA.119.015292. Yoo SJ, Prsa M, Schantz D, Grosse-Wortmann L, Seed M, Kim TK, et al. MR assessment of abdominal circulation in Fontan physiology. Int J Cardiovasc Imaging. 2014;30(6):1065-72. doi: 10.1007/s10554-014-0424-x. Angelotti A, Dhesi M, Bansal SS, Bradley EA. Novel immunologic mechanisms for Fontan-associated liver disease. Int J Cardiol Congenit Heart Dis. 2024;19:100554. doi: 10.1016/j.ijcchd.2024.100554. Magdo HS, Stillwell TL, Greenhawt MJ, Stringer KA, Yu S, Fifer CG, et al. Immune Abnormalities in Fontan Protein-Losing Enteropathy: A Case-Control Study. J Pediatr. 2015;167(2):331-7. doi: 10.1016/j.jpeds.2015.04.061. Lona-Reyes JC, Torres-Molina S, Flores-Fong LE, Estrada-Arce EV, Rivera-Chávez E, Núñez-Núñez ME, et al. Protein-losing enteropathy in a preschool patient with intestinal tuberculosis. Gastroenterol Hepatol. 2022;45(3):204-205. English, Spanish. doi: 10.1016/j.gastrohep.2020.08.017. De Boer RJ, Homann D, Perelson AS. Different dynamics of CD4+ and CD8+ T cell responses during and after acute lymphocytic choriomeningitis virus infection. J Immunol. 2003;171(8):3928-35. doi: 10.4049/jimmunol. Additional Declarations No competing interests reported. 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1","display":"","copyAsset":false,"role":"figure","size":67395,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between immunological variables and diagnosis of protein-losing enteropathy.\u003c/p\u003e\n\u003cp\u003eDeficiencies in immunoglobulin (IgA, IgG) and lymphocyte subpopulations (CD4, CD19) were more frequently observed in the PLE group than in those without PLE.\u003c/p\u003e\n\u003cp\u003eNK - Natural Killers, IgG – Immunoglobulin G, IgM – Immunoglobulin M, IgA – Immunoglobulin A.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7826456/v1/28dc4a77334d2a9e519e6730.png"},{"id":96355031,"identity":"cd98fd88-3273-498f-838c-eda35b4f431d","added_by":"auto","created_at":"2025-11-20 08:14:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":116691,"visible":true,"origin":"","legend":"\u003cp\u003eRelationship between lymphopenia and liver parameters\u003c/p\u003e\n\u003cp\u003eThere were no significant associations between lymphopenia and liver function parameters including PLT count, INR, albumin level as well as AST, ALT and GGT activity.\u003c/p\u003e\n\u003cp\u003ePLT – platelets, INR - International Normalized Ratio, ALT- Alanine aminotransferase, AST - Aspartate aminotransferase, GGT - Gamma-glutamyltransferase.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7826456/v1/58e05d37f1521c46127c7620.png"},{"id":96452992,"identity":"c59d8249-8467-4eca-a3d7-0206fc04df80","added_by":"auto","created_at":"2025-11-21 09:57:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1114240,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7826456/v1/c370df16-7daf-47d4-b3cb-7611780dd50d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Small Intestinal Bacterial Overgrowth and Immunological Disturbances in Fontan- Associated Enteropathy","fulltext":[{"header":"Background","content":"\u003cp\u003eThe Fontan operation is palliative procedure dedicated for patients with functional single ventricle congenital heart lesions. The outcomes of the surgery have improved with 30 years survival rates reaching up to 85% [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Initially, the operation was made in the form of intracardiac Fontan (ICF) connection. However, ICF was associated with hypertrophy of right atrium and subsequently to supraventricular arrhythmias as well as problems of increased venous pressure, and obstruction of the systemic venous to pulmonary arterial pathway [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Those complications led to the development of extracardiac Fontan (ECF) technique offering improved hemodynamics and a lower incidence of arrhythmias [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. On the other hand, recent data suggests that ECF may be associated with faster development of cirrhosis [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eDespite high survival rate after Fontan procedure, some gastrointestinal complications, including protein-losing enteropathy (PLE) and Fontan-Associated Liver Disease (FALD) remain severe and potentially life-threatening [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The above-mentioned complications are mainly caused by organ congestion related to high central venous pressure (CVP), chronic heart failure from low cardiac output, and hypoxia, all of which may contribute over time to multiorgan dysfunction [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe PLE affects 5\u0026ndash;15% patients following the Fontan procedure. PLE is characterized by the loss of serum proteins into the gut lumen, leading to chronic diarrhea, general abdominal discomfort and peripheral edema [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In the literature, the diagnostic criteria for PLE are inconsistent, they generally include clinical symptoms, hypoalbuminemia and augmented enteric protein loss (elevation of the fecal α-1 antitrypsin level) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Several factors contribute to the development of PLE including impaired lymphatic drainage due to elevated CVP, obstruction of the thoracic duct, increased mesenteric resistance, lymphatic congestion and reduced mesenteric flow, all leading to distention of hepatoduodenal lymphatic channels and intestinal mucosa damage [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. These pathological processes lead to enteric loss of albumin, immunoglobulins, lymphocytes and clotting factors which manifest clinically as chronic diarrhea, peripheral edema, ascites and immune deficiency [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Recent data showed that PLE in Fontan patients is associated with significant alterations of T cell differentiation promoted by several miRNA controlled immunological pathways [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAll patients after Fontan surgery develop Fontan-associated liver disease (FALD), a distinctive type of congestive hepatopathy primarily triggered by increased CVP and decreased cardiac output [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The circulation disturbances cause intrahepatic nitric oxide concentration that in turn promotes hepatocellular necrosis, atrophy, and fibrinogenic responses [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Additionally, increased lymph angiogenesis in the liver contributes to dilatation of the hepatic sinusoids leading to poor lymph drainage. These factors promote liver dysfunction, tissue inflammation, and fibrosis [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eConsidering the intestinal and general immune dysregulation, enteropathy, circulation disturbances and liver disfunction, all of which are potential factors leading to gastrointestinal microbial imbalances [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], the Small Intestinal Bacterial Overgrowth (SIBO) in the patients after Fontan surgery may be suspected. The SIBO is defined as an excessive proliferation of bacteria (\u0026gt;\u0026thinsp;10\u003csup\u003e3\u003c/sup\u003e\u0026ndash;10\u003csup\u003e5\u003c/sup\u003e CFU/mL) in the small intestine, alteration in the bacterial composition, or both. The microbiota of SIBO patients is mainly characterized by overgrowth of colonic bacteria, including coliform bacteria and anaerobes, which contribute to carbohydrates fermentation, decreased vitamin and micronutrient absorption and subsequent mucosal inflammation [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. To date, only one abstract in the literature has reported the SIBO occurrence in this patient population [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe primary aim of this study was to examine the incidence of SIBO in patients after Fontan surgery and healthy subjects. Additionally, we aimed to compare enteropathy, immunological disturbances and SIBO prevalence between the patients after ICF and ECF procedures.\u003c/p\u003e\u003cp\u003ePatients:\u003c/p\u003e\u003cp\u003eThis was a cross-sectional observational study included patients aged 5\u0026ndash;18 years who had undergone the Fontan operation (study group) and were hospitalized between 2021 and 2024 at either the Department of Gastroenterology, Allergology and Paediatrics, Polish Mother\u0026rsquo;s Memorial Hospital \u0026ndash; Research Institute in Lodz or the Department of Paediatric Cardiology, Jagiellonian University Medical College, Cracow, Poland. All subjects were under the care of local cardiology and/or gastroenterology outpatients\u0026rsquo; clinic. Children and adolescents without chronic gastrological and cardiological history and lack of contraindications to participate were included as a convenience sample (control group). The exclusion criteria included: hospitalization due to acute conditions (trauma, infection, exacerbation of chronic disease), chronic inflammatory gastrointestinal or kidney diseases, endocrine disorders, malignancy and/or use of antibiotics or other medications that could influence the Lactulose Hydrogen Breath Test (LHBT) results (described below).\u003c/p\u003e\u003cp\u003eA detailed cardiovascular history of the examined children was collected, including type of congenital heart defect (hypoplastic left heart syndrome, hypoplastic right heart syndrome), presence of fenestration, type of Fontan operation (ICF, ECF) and age at the time of surgery.\u003c/p\u003e\u003cp\u003eAll patients underwent anthropometric measurements (body weight [kg], height [cm]). Body mass index (BMI) was calculated using the formula weight/height\u003csup\u003e2\u003c/sup\u003e and was subsequently converted into Z-scores and percentiles based on national growth charts [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Additionally, during clinical examinations the presence of diarrhea, edema and ascites occurrence was noted.\u003c/p\u003e\u003cp\u003eLactulose Hydrogen Breath Test\u003c/p\u003e\u003cp\u003eHydrogen breath test was used as a noninvasive test for detecting SIBO occurrence (Gastrolyzer gastro plus, Bedfont Scientific, England). All subjects fasted for 8 to 12 hours prior to the test. A 4-week interval between antibiotic, laxatives, probiotics and prokinetics was required [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Foods rich in malabsorbed carbohydrates (fresh vegetables and fruits) were excluded from diet for 3 days before test. After brushing the teeth, the baseline breath samples were collected (a hydrogen level of \u0026le;\u0026thinsp;10 ppm was required to proceed with the test). The LHBT was then conducted using 10 g of lactulose. After consuming the dissolved lactulose substrate, breath samples were collected every 15 min for the next 2 hours. During the testing, patients were not allowed to sleep, eat, drink, or engage in any vigorous activity. The SIBO was diagnosed as if there was a rise in hydrogen of \u0026ge;\u0026thinsp;20 ppm above the baseline value within 90 minutes [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eBlood sampling and laboratory analyses\u003c/p\u003e\u003cp\u003eVenous blood samples were collected after 12 h of fasting into standard vacuum tubes. Laboratory tests including blood morphology, biochemical parameters and lymphocyte subpopulation were performed. The following parameters and laboratory methods were used: potassium and sodium levels (ion-selective electrode method), total protein concentrations (endpoint method), albumin (bromocresol green method), AST, ALT, GGT (the immunoenzymatic assay according to the International Federation of Clinical Chemistry method (IFCC)), IgA, IgG, IgM concentrations (IFCC turbidimetric method), NT-proBNP concentration (electrochemiluminescence immunoassay). All biochemical analyses were performed on following equipment: Beckman Coulter: DxC 700AU and Cobas Pro e801 according to the manufacturer's recommendations. INR was exanimated with coagulometric method (ACL550, Werfen).\u003c/p\u003e\u003cp\u003ePeripheral blood lymphocyte subpopulations were determined by flow cytometry using commercially available kits (BD Multitest 6-Color TBNK with BD Trucount Tubes).\u003c/p\u003e\u003cp\u003eAnalysis was performed on a Becton Dickinson BD FACSCanto II flow cytometer. Results were expressed as absolute values ​​and percentages for CD3+, CD4+, CD8\u0026thinsp;+\u0026thinsp;T lymphocytes, CD19 B lymphocytes and CD56\u0026thinsp;+\u0026thinsp;CD16\u0026thinsp;+\u0026thinsp;NK cell populations.\u003c/p\u003e\u003cp\u003eFecal alpha-1-antitrypsin level was measured with ELISA method, and the results were expressed in \u0026micro;g/g (norm range\u0026thinsp;\u0026lt;\u0026thinsp;268).\u003c/p\u003e\u003cp\u003eProtein-losing enteropathy\u003c/p\u003e\u003cp\u003ePLE was diagnosed based on evidence of increased enteric protein loss, indicated by elevated fecal alpha-1-antitrypsin levels above the normal reference range, subclinical or associated with hypoalbuminemia (serum albumin\u0026thinsp;\u0026lt;\u0026thinsp;3.5 g/dL) and at least one of the following clinical signs: peripheral edema, abdominal distension or discomfort, diarrhea, or the presence of serous effusions (ascites, pleural, or pericardial effusions) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eCategorical variables were reported as counts and percentages. Continuous variables were summarized using the median and interquartile (IQR), along with lower and upper quartile. Comparisons between categorical variables were conducted using the chi-squared test (χ\u0026sup2;) with Yates\u0026rsquo; continuity correction or Fisher\u0026rsquo;s exact test, as appropriate. Continuous variables between two independent groups were compared using the nonparametric Mann\u0026ndash;Whitney U test. Associations between continuous variables were assessed using Spearman\u0026rsquo;s rank correlation coefficient. Missing data was imputed using the mean value of the respective variable. To adjust for potential confounding factors, generalized linear models (GLMs) were applied. A two-sided p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. All analyses were performed using RStudio (version 4.4.1).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 88 children and adolescents (51,13% males) with a median age of 12.6 years were enrolled in the study including 68 subjects after Fontan surgery and 20 controls. The anthropometric and biochemical features of the studied group are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The results of the LHBT showed no statistically significant differences in SIBO occurrence between study and control groups (n\u0026thinsp;=\u0026thinsp;22 (32.35%) vs. n\u0026thinsp;=\u0026thinsp;9 (45%); p\u0026thinsp;=\u0026thinsp;0.44).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharacteristic of the study population\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eStudy group (n\u0026thinsp;=\u0026thinsp;68)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eControl group (n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBody weight [kg]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e45.44 (28.5-56.24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40.85 (27.4-51.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeight [cm]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e156.5 (131.5\u0026ndash;166)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e147.5 (128-165.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.78\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBMI [kg/m2]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18.03 (16.23\u0026ndash;21.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17.32 (14.21\u0026ndash;20.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBody weight [z-score]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.38 (-1.12\u0026ndash;0.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.5 (-1.21\u0026ndash;0.32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeight [z-score]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.86 (-1.57\u0026ndash;0.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.06 (-0.48\u0026ndash;0.69)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eBMI [z-score]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-0.05 (-0.92\u0026ndash;0.71)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-0.54 (-1.55\u0026ndash;0.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.29\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRBC [10^6/uL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5.06 (4.81\u0026ndash;5.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.72 (4.32\u0026ndash;4.81)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHb [g/dL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14.55 (13.8\u0026ndash;15.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13.6 (12.2\u0026ndash;14.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHct [%]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e41.9 (39.5\u0026ndash;45.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e38.2 (34.4\u0026ndash;39.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePLT [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e200 (156.5\u0026ndash;263.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e275 (250\u0026ndash;308)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWBC [10^3/uL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.07 (4.78\u0026ndash;7.57)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.87 (5.44\u0026ndash;7.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.68\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSodium [mmol/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e138 (137\u0026ndash;139)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e139 (138\u0026ndash;140)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePotassium [mmol/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.31 (4.08\u0026ndash;4.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.1 (4.09\u0026ndash;4.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.04\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalcium [mmol/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.45 (2.29\u0026ndash;2.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.5 (2.38\u0026ndash;2.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.75\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eINR\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.3 (1.2\u0026ndash;1.4)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.1 (1.1\u0026ndash;1.2)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eALT [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37.15 (30.75\u0026ndash;44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25 (22.8\u0026ndash;32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eALT [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27 (21.75\u0026ndash;32.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14 (10\u0026ndash;16)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGGT [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e47 (33\u0026ndash;62)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13.5 (10.75\u0026ndash;15.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.00\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues are expressed as median (IQR)\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eBMI - Body Mass Index, RBC \u0026ndash; Red Blood Count, Hb \u0026ndash; Hemoglobin, Hct- Hematocrit, PLT \u0026ndash; platelets, WBC \u0026ndash; White Blood Count, INR - International Normalized Ratio, ALT- Alanine aminotransferase, AST - Aspartate aminotransferase, GGT - Gamma-glutamyltransferase.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eProtein-losing enteropathy and immunological status\u003c/p\u003e\u003cp\u003ePLE was confirmed in 11 patients (16.2%) from the study group. There was no statistically significant difference in the age [months] at which the Fontan procedure was performed between patients with and without PLE (36 (30.5\u0026ndash;41.0) vs. 48 (35.0\u0026ndash;58.0); p\u0026thinsp;=\u0026thinsp;0.07). Clinical examination revealed no significant difference in the occurrence of ascites between the groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, peripheral edema was significantly more common in the PLE group (6/11; 54.55%) compared to the non-PLE group (3/57; 5.26%; p\u0026thinsp;=\u0026thinsp;0.00). Patients in the PLE group demonstrated significantly lower serum albumin and IgG concentrations, reduced total lymphocyte count and subpopulation of CD3, CD4 and CD8 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The analysis of laboratory parameters in the studied groups is presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of Laboratory Parameters Between Patients with and without Protein-losing Enteropathy (PLE)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePLE (n\u0026thinsp;=\u0026thinsp;11)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eWithout PLE (n\u0026thinsp;=\u0026thinsp;57)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAST [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e40.20 (30.60\u0026ndash;45.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e37.10 (30.90\u0026ndash;43.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.758\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eALT [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e32.0 (28.0\u0026ndash;40.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25.0 (21.0\u0026ndash;30.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.069\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eGGT [U/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e55.0 (29.0\u0026ndash;88.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e47.0 (35.0-58.73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.594\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNT-proBNP [pg/mL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e135.60 (108.20-310.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e141 (68\u0026ndash;271)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.565\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eINR\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.20 (1.15\u0026ndash;1.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.30 (1.20\u0026ndash;1.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.093\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAlbumin [g/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.44 (2.58\u0026ndash;3.84)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.70 (4.50\u0026ndash;4.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTP [g/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5.65 (4.23\u0026ndash;5.98)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.20 (6.84\u0026ndash;7.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eRBC [10^6/uL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5.18 (4.96\u0026ndash;5.54)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.01 (4.80\u0026ndash;5.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.159\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHb [g/dL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e14.80 (14.15\u0026ndash;15.15)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e14.50 (13.80\u0026ndash;15.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.745\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHct [%]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e42.50 (41.10\u0026ndash;45.05)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41.70 (39.50\u0026ndash;45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.617\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePLT [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e234 (181\u0026ndash;275.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e197 (152\u0026ndash;262)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.185\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eWBC [10^3/uL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6.44 (4.58\u0026ndash;7.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.89 (4.80\u0026ndash;7.59)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.907\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLymphocytes [10^3/uL]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.90 (0.66\u0026ndash;1.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.40 (1.03\u0026ndash;2.20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSodium [mmol/l]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e137.0 (135.50\u0026ndash;139.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e138.0 (137.0\u0026ndash;139.0)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.255\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePotassium [mmol/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.0 (3.87\u0026ndash;4.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.39 (4.10\u0026ndash;4.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.006\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCalcium [mmol/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.13 (2.05\u0026ndash;2.27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.47 (2.37\u0026ndash;2.58)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgG [g/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.83 (2.55\u0026ndash;6.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.97 (8.39\u0026ndash;11.85)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgM [g/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.87 (0.57\u0026ndash;1.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.81 (0.65\u0026ndash;1.03)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;0.999\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgA [g/L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.96 (0.50\u0026ndash;1.28)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.30 (0.99\u0026ndash;1.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.052\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD3 [10^3/ul]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.40 (0.23\u0026ndash;0.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.76 (0.58\u0026ndash;0.93)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD4 [10^3/ul]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.18 (0.12\u0026ndash;0.24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.47 (0.34\u0026ndash;0.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD8 [10^3/ul]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.16 (0.07\u0026ndash;0.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.24 (0.18\u0026ndash;0.32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD19 [10^3/ul]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.29 (0.16\u0026ndash;0.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.33 (0.25\u0026ndash;0.39)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.576\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNK [10^3/ul]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.22 (0.16\u0026ndash;0.41)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.23 (0.14\u0026ndash;0.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.658\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eValues are expressed as median (IQR)\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"4\"\u003eALT - Alanine aminotransferase, AST - Aspartate aminotransferase, GGT - Gamma-glutamyltransferase, INR - International Normalized Ratio, TP \u0026ndash; total protein, RBC \u0026ndash; Red Blood Count, Hct \u0026ndash; Hematocrit, Hb \u0026ndash; Hemoglobin, PLT \u0026ndash; platelets, WBC \u0026ndash; White Blood Count, INR - International Normalized Ratio, IgG \u0026ndash; Immunoglobulin G, IgM \u0026ndash; Immunoglobulin M, IgA \u0026ndash; Immunoglobulin A, NK- Natural Killers.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eDeficiencies in immunoglobulin and lymphocyte subpopulations were more frequently observed in the PLE group than in those without PLE. Specifically, IgG deficiency was found in 8 patients (72.73%) with PLE vs. 2 patients (3.51%) without enteropathy (p\u0026thinsp;\u0026lt;\u0026thinsp;0.00), IgA deficiency in 4 patients (36.36%) vs. 6 patients (10.53%, p\u0026thinsp;=\u0026thinsp;0.04), CD4 deficiency in 11 patients (100%) vs. 32 patients (56.14%, p\u0026thinsp;=\u0026thinsp;0.00), and CD19 deficiency in 5 patients (45.45%) vs. 8 patients (14.04%, p\u0026thinsp;=\u0026thinsp;0.02). The relationship between immunological variables and the diagnosis of PLE is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There was no statistically significant difference in the occurrence of SIBO between patients with and without PLE (n\u0026thinsp;=\u0026thinsp;3 (27.27%) vs. n\u0026thinsp;=\u0026thinsp;19 (33.33%); p\u0026thinsp;\u0026gt;\u0026thinsp;0.99). No significant associations were found between lymphopenia and liver function parameters including PLT count, INR, albumin level as well as AST, ALT and GGT activity (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eType of Fontan operation\u003c/p\u003e\u003cp\u003eThe analysis of medical history showed that 24 patients (35,3%) underwent ICF while 44 subjects (64,7%) had ECF procedures.\u003c/p\u003e\u003cp\u003eThe PLE (n\u0026thinsp;=\u0026thinsp;7 (63.64%) vs. n\u0026thinsp;=\u0026thinsp;4 (36.36%); p\u0026thinsp;=\u0026thinsp;0.04) and hypoalbuminemia (n\u0026thinsp;=\u0026thinsp;6 (25.0%) vs. n\u0026thinsp;=\u0026thinsp;1 (2.27%); p\u0026thinsp;=\u0026thinsp;0.00) were more frequently observed in the ICF group compared to the ECF procedure. Taking into account clinical symptoms, the peripheral edema (n\u0026thinsp;=\u0026thinsp;7 (29.17%) vs. n\u0026thinsp;=\u0026thinsp;2 (4.55%); p\u0026thinsp;=\u0026thinsp;0.00) and ascites (n\u0026thinsp;=\u0026thinsp;4 (16.67%) vs. n\u0026thinsp;=\u0026thinsp;0; p\u0026thinsp;=\u0026thinsp;0.01) were more frequently observed in the ICF group. Additionally, SIBO was more common in the ICF group (n\u0026thinsp;=\u0026thinsp;13 (54.17%) vs. n\u0026thinsp;=\u0026thinsp;9 (20.45%); p\u0026thinsp;=\u0026thinsp;0.00). Initial laboratory analysis suggested immunological differences related to the type of Fontan procedure. However, due to significant difference in age at the time of operation (ICF procedure 33.50 months (27.50\u0026ndash;40.25) vs. ECF 54 months (41.75\u0026ndash;67); p\u0026thinsp;\u0026lt;\u0026thinsp;0.00) a statistical adjustment was performed. After adjusting for age no significant immunological differences remained between the groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Nevertheless, SIBO was more frequent in patients after ICF compared to those after ECF procedure (p\u0026thinsp;=\u0026thinsp;0.01) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAnalysis of clinical and immunological variables according to Fontan procedure type.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep adjusted with age at surgery\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eICF (n\u0026thinsp;=\u0026thinsp;24)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eECF (n\u0026thinsp;=\u0026thinsp;44)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEnteropathy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes/No\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (63.64)/17 (29.82)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4 (36.36)/40 (70.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.04\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSIBO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes/No\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e13 (54.17)/9 (20.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9 (20.45)/35 (79.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.00\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAscites\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes/No\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (16.67)/20 (83.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0/44 (100)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePeripheral oedema\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes/No\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7 (29.17)/17 (70.83)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2 (4.55%)/42 (95.45%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.00\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHypoalbuminaemia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYes/No\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 (25)/18 (75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (2.27%)/43 (97.73%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.00\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLymphocytes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (20.83)/19 (79.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16 (36.36%)/28 (63.64%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNK\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (16.67)/20 (83.33%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8 (18.18%)/36 (81.82%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;0.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.39\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4 (16.67%)/20 (83.33%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9 (20.45%)/35 (79.55%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;0.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21 (87.50%)/3 (12.50%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e33 (75%)/11 (25%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e19 (79.17%)/5 (20.83%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e24 (54.55%)/20 (45.45%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e23 (95.83%)/1 (4.17%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e32 (72.73%)/12 (27.27%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.02\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIgA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6 (25%)/18 (75%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4 (9.09%)/40 (90.91%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIgM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (4.17%)/23 (95.83%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8 (18.18%)/36 (81.82%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIgG\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDeficit/Norm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (20.83%)/19 (79.17%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5 (11.36%)/39 (88.64%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eValues are expressed as n (%).\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eICF- intracardiac Fontan, ECF \u0026ndash; extracardiac Fontan, SIBO \u0026ndash; small intestinal bacterial overgrowth, NK- Natural Killers, IgG \u0026ndash; Immunoglobulin G, IgM \u0026ndash; Immunoglobulin M, IgA \u0026ndash; Immunoglobulin A.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of immunological parameters by type of Fontan procedure.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eVariable\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep adjusted for age at surgery time\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eICF (n\u0026thinsp;=\u0026thinsp;24)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eECF (n\u0026thinsp;=\u0026thinsp;44)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgG [g/l]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8.26 (7.10\u0026ndash;10.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.98 (7.67\u0026ndash;11.46)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgM [g/l]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.76 (0.56\u0026ndash;1.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.86 (0.68\u0026ndash;1.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.52\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eIgA [g/l]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.14 (0.88\u0026ndash;1.48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.39 (0.96\u0026ndash;1.74)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD3 [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.54 (0.42\u0026ndash;0.74)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.78 (0.58\u0026ndash;0.97)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.01\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD4 [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.33 (0.24\u0026ndash;0.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.48 (0.32\u0026ndash;0.61)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.00\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD8 [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.19 (0.15\u0026ndash;0.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.25 (0.16\u0026ndash;0.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eCD19 [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.34 (0.26\u0026ndash;0.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.32 (0.20\u0026ndash;0.42)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.45\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eNK [10^3/\u0026micro;L]\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.24 (0.15\u0026ndash;0.36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.22 (0.14\u0026ndash;0.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.71\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eValues are expressed as median (IQR)\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eICF- intracardiac Fontan, ECF \u0026ndash; extracardiac Fontan, IgG \u0026ndash; Immunoglobulin G, IgM \u0026ndash; Immunoglobulin M, IgA \u0026ndash; Immunoglobulin A, NK- Natural Killers.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAlthough recent studies have highlighted the role of gut dysbiosis in cardiovascular diseases [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], gastrointestinal disorders in patients after Fontan surgery remain poorly understood. Hepatic dysfunction and PLE, which commonly occur in this population, may significantly affect gut microbiome colonization and composition. The literature data on this topic are scarce [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. One case-control study involving patients after Fontan procedure indicated that gut microbiota dysbiosis is connected with active PLE. Moreover, changes in the bacterial composition of the gut microbiota and decreased diversity may be associated with the severity of PLE [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Wang et al. showed that alteration in the microbial composition and biodiversity may serve as distinctive characteristics of patients who have undergone Fontan circulation [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. To the best of our knowledge, no previous studies have investigated the relationship between SIBO and the Fontan procedure. However, it is well established that altered gut perfusion and circulatory disturbances are associated with a high prevalence of SIBO in patients with cardiovascular diseases [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn our study, we found no significant differences in the incidence of SIBO between the study and control groups, nor between patients after Fontan procedure with and without PLE. On the other hand, the results of LHBT were significantly associated with the type of Fontan procedure regardless of the age of the surgery. Despite the absence of differences in PLE and immunological disturbances between ECF and ICF groups after adjusting for age at the time of surgery, the explanation for increase of SIBO incidence after ICF procedure remains unclear. This phenomenon may be due to different hemodynamic parameters in both groups which could influence intestinal blood supply. Abdominal organs are especially vulnerable to alterations in hemodynamics as hepatic blood flow is mostly dependent on portal venous circulation, which relies on a low-pressure gradient between the portal and hepatic veins [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Consequently, elevated systemic venous pressure affects the hemodynamic balance impairing both liver and gut function [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The results of Kisamori et al. showed that ECF is associated with conduit obstruction accelerating liver fibrosis and cirrhosis [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This observation suggests that differences in surgical technique may lead to distinct hemodynamics potentially influencing gastrointestinal function. However, this thesis requires further investigation.\u003c/p\u003e\u003cp\u003eOur results related to lymphocyte count and immunological parameters are similar to observation reported by other authors. Lymphopenia is common in patients after Fontan operation; however the etiology of this phenomenon remains poorly understood [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Some authors associate the occurrence of lymphopenia not only with PLE but also with FALD. It has previously been shown that lymphopenia is common in adult Fontan patients and is associated with markers of portal hypertension [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Moreover, lymphopenia with thrombocytopenia may serve as a simple primary non-invasive diagnostic tool for early risk stratification of FALD onset [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In the past leucopenia in cirrhosis was attributed to suppressed in vitro leucocyte proliferation. More recent data showed that attenuation in circulating lymphocytes may result from peripheral (liver) recruitment. Liver samples from Fontan patients demonstrated upregulation of endothelial cells and total lymphocytes, especially of NK and T-cells. The authors concluded that hepatic changes in adolescent Fontan patients are triggered by T-cells which are contributing to the early development and possible progression of FALD [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In our study we found no significant correlation between hepatic parameters and PLE. Those results are probably due to the fact that the study included only children - in whom all mechanisms responsible for lymphopenia were not fully yet developed.\u003c/p\u003e\u003cp\u003eIn our study the PLE was associated with a significant lower lymphocyte count compared to subjects without enteropathy. This finding is consistent with previous observation and results from the lymphocyte loss in the gastrointestinal tract by abnormal intraluminal lymphatic drainage [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Prior studies have shown that enteropathy is connected with loss of particular lymphocyte subpopulation, however the data remain inconsistent [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. In our cohort, patients with PLE showed decreased count of CD3, CD4 and CD8 cells, however only CD4 and CD19 lymphocytes were below the normal range. Our findings support the hypothesis that the immune system is involved in the development and maintenance of PLE. The differences in peripheral lymphocyte count may result from different half-lives of lymphocyte subpopulation [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In the patients with PLE several authors showed a selective loss of CD4 lymphocytes and slightly reduced levels of CD8 lymphocytes resulting in decreased CD4/CD8 ratio [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Magdo et al. suggested that this is effect of selective transport of CD4 cells into the lymphatics, supported by the finding of a significantly higher CD4:CD8 ratio in body fluid (such as chylothorax or chyloperitoneal fluid) compared to the blood [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. On the other hand, more recent data indicate that immunological disturbances in this group of patients may be related to significant alterations in T cell differentiation, that is dysregulated by several miRNA controlling immunological pathways [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThere are potential limitations of our study. First, including the pioneering data on SIBO occurrence in patients after ICF and ECF procedures, we did not include hemodynamic measurements or MRI results, which could have provided further insight into observed findings. Second, the diagnosis of SIBO was based on the LHBT results rather than the duodenal aspiration that may influence reliability. However, LHBT was chosen to avoid exposing the patients to an invasive procedure.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eOur results confirmed the correlation between PLE occurrence and immunological disturbances in patients after Fontan procedure. SIBO occurrence was associated with the type of Fontan operation but no with PLE, lymphopenia and lymphocyte subpopulation intestinal lost. These findings may reflect differences in gut perfusion between ICF and ECF group, however this hypothesis requires confirmation through studies including hemodynamic parameters and abdominal MRI scans.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eIintracardiac Fontan (ICF)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExtracardiac Fontan (ECF)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eProtein-losing enteropathy (PLE)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFontan-Associated Liver Disease (FALD)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCentral venous pressure (CVP)\u003c/p\u003e\n\u003cp\u003eFontan-associated liver disease (FALD),\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSmall Intestinal Bacterial Overgrowth (SIBO)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLactulose Hydrogen Breath Test (LHBT)\u003c/p\u003e\n\u003cp\u003eBody mass index (BMI)\u003c/p\u003e\n\u003cp\u003eInternational Federation of Clinical Chemistry method (IFCC)\u003c/p\u003e\n\u003cp\u003eInterquartile (IQR)\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study followed the standards of the Declaration of Helsinki and was approved by Bioethics Committee of the Polish Mothers Memorial Hospital - Research Institute (PMMH-RI 42/2021) and Jagiellonian University Bioethics Committee (1072.6120.141.2022), respectively. All parents and children \u0026ge;16\u0026thinsp;years old provided written informed consent before participation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo conflict of interest, financial or other, exists.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was funded by the Polish Ministry of Science \u0026amp; Higher Education, Polish Mother\u0026rsquo;s Memorial Hospital \u0026ndash; Research Institute - Internal Grant no 3GW/II/2021 and Jagiellonian University CM Internal Grant no N41/DBS/000905.\u003c/p\u003e\n\u003cp skip=\"true\"\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnna Socha-Banasiak - conception and design of the work, analysis and interpretation of data, writing the manuscript, tables and figures conception.\u003c/p\u003e\n\u003cp\u003eAnna Mazurek-Kula - recruitment for the study, analysis and interpretation of data, final approval of the version to be published.\u003c/p\u003e\n\u003cp\u003eNatalia Nawara-Węgrzyn - recruitment for the study, analysis and interpretation of data, final approval of the version to be published.\u003c/p\u003e\n\u003cp\u003eSebastian G\u0026oacute;reczny - conception or design of the work, final approval of the version to be published.\u003c/p\u003e\n\u003cp\u003eKatarzyna Kucharska - recruitment for the study, analysis and interpretation of data, statistical analysis, final approval of the version to be published.\u003c/p\u003e\n\u003cp\u003eElżbieta Czkwianianc - analysis and interpretation of data, final approval of the version to be published.\u003c/p\u003e\n\u003cp\u003eKinga Kowalska-Duplaga- analysis and interpretation of data, final approval of the version to be published.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eKhairy P, Fernandes SM, Mayer JE, Jr. Long-term survival, modes of death, and predictors of mortality in patients with Fontan surgery. Circulation. 2008;117(01):85\u0026ndash;92. doi: 10.1161/CIRCULATIONAHA.107.738559.\u003c/li\u003e\n \u003cli\u003eTalwar S, Sengupta S, Choudhary SK. The intra-extracardiac Fontan: preliminary results. Indian J Thorac Cardiovasc Surg. 2020;36(3):193-198. doi: 10.1007/s12055-019-00862-7. Epub 2019 Oct 18.\u003c/li\u003e\n \u003cli\u003eTalwar S, Divya A, Makhija N, Choudhary SK, Airan B. Immediate and early post-operative sequelae of off-pump total cavopulmonary connection. Indian J Thorac Cardiovasc Surg. 2018;34:468\u0026ndash;75.\u003c/li\u003e\n \u003cli\u003eKisamori E, Venna A, Chaudhry HE, Desai M, Tongut A, Mehta R, et al. Alarming rate of liver cirrhosis after the small conduit extracardiac Fontan: A comparative analysis with the lateral tunnel. J Thorac Cardiovasc Surg. 2024;168(4):1221-1227.e1. doi: 10.1016/j.jtcvs.2024.04.013.\u003c/li\u003e\n \u003cli\u003eBarracano R, Merola A, Fusco F, Scognamiglio G, Sarubbi B. Protein-losing enteropathy in Fontan circulation: Pathophysiology, outcome and treatment options of a complex condition. Int J Cardiol Congenit Heart Dis. 2022;7:100322. doi: 10.1016/j.ijcchd.2022.100322.\u003c/li\u003e\n \u003cli\u003eEmamaullee J, Zaidi AN, Schiano T, Kahn J, Valentino PL, Hofer RE, et al. Fontan-Associated Liver Disease: Screening, Management, and Transplant Considerations. Circulation. 2020 Aug;142(6):591-604. doi: 10.1161/CIRCULATIONAHA.120.045597.\u003c/li\u003e\n \u003cli\u003eOhuchi H. Where Is the \u0026quot;Optimal\u0026quot; Fontan Hemodynamics? Korean Circ J. 2017;47(6):842-857. doi: 10.4070/kcj.2017.0105. Epub 2017 Sep 18.\u003c/li\u003e\n \u003cli\u003eKoch A, Hofbeck M, Feistel H, Buheitel G, Singer H. Circumscribed intestinal protein loss with deficiency in CD4+ lymphocytes after the Fontan procedure. Eur J Pediatr 1999;158: 847\u0026ndash;850.\u003c/li\u003e\n \u003cli\u003eThorne SA, Hooper J, Kemp M, Somerville J. 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Epub 2021 Feb 19.\u003c/li\u003e\n \u003cli\u003ede Lange C, M\u0026ouml;ller T, Hebelka H. Fontan-associated liver disease: Diagnosis, surveillance, and management. Front Pediatr. 2023;11:1100514. doi: 10.3389/fped.2023.1100514.\u003c/li\u003e\n \u003cli\u003e\u003cem\u003e\u003ccite\u003eRychik J, Goldmuntz E. Invited commentary: the hunt for mechanistic origins of liver fibrosis in the Fontan circulation. World J Pediatr Congenit Heart Surg. 2021; 12(2):173\u0026ndash;5. 10.1177/2150135121989974.\u003c/cite\u003e\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003e\u003ccite\u003eChung C, Iwakiri Y. The lymphatic vascular system in liver diseases: its role in ascites formation.\u0026nbsp;\u003c/cite\u003e\u003c/em\u003e\u003ccite\u003eClin Mol Hepatol. 2013; 19(2):99\u0026ndash;104. 10.3350/cmh.2013.19.2.99\u003c/cite\u003e\u003c/li\u003e\n \u003cli\u003eRoszkowska P, Klimczak E, Ostrycharz E, Rączka A, Wojciechowska-Koszko I, Dybus A, et al. Small Intestinal Bacterial Overgrowth (SIBO) and Twelve Groups of Related Diseases-Current State of Knowledge. Biomedicines. 2024;12(5):1030. doi: 10.3390/biomedicines12051030.\u003c/li\u003e\n \u003cli\u003ehttps://www.uni-kiel.de/aepc/2016/aepcHandouts/Handout_602.pdf.\u003c/li\u003e\n \u003cli\u003eKułaga Z, Grajda A, Gurzkowska B, G\u0026oacute;źdź M, Wojtyło M, Swiąder A, et al. Polish 2012 growth references for preschool children. Eur J Pediatr. 2013;172(6):753\u0026ndash;61.\u003c/li\u003e\n \u003cli\u003eKułaga Z, R\u0026oacute;żdżyńska-Świątkowska A, Grajda A, Gurzkowska B, Wojtyło M, G\u0026oacute;źdź M, et al. Percentile charts for growth and nutritional status assessment in polish children and adolescents from birth to 18 year of age. Standrady Medyczne/Pediatria. 2015;12:119\u0026ndash;35\u003c/li\u003e\n \u003cli\u003e\u0026nbsp;Eisenmann A, Amann A, Said M, et al. Implementation and interpretation of hydrogen breath tests. J Breath Res 2008; 2: 046002 doi: 10.1088/1752-7155/2/4/046002.\u003c/li\u003e\n \u003cli\u003e\u003ccite\u003ePimentel M, Saad RJ, Long MD, et al. ACG clinical guideline: Small intestinal bacterial overgrowth. Am J Gastroenterol 2020;115(2):165\u0026ndash;78.\u003c/cite\u003e\u003c/li\u003e\n \u003cli\u003eCangemi DJ, Lacy BE, Wise J. Diagnosing Small Intestinal Bacterial Overgrowth: A Comparison of Lactulose Breath Tests to Small Bowel Aspirates. Dig Dis Sci. 2021;66(6):2042-2050. doi: 10.1007/s10620-020-06484-z.\u003c/li\u003e\n \u003cli\u003eAlsaied T, Lubert AM, Goldberg DJ, Schumacher K, Rathod R, Katz DA, et al. Protein losing enteropathy after the Fontan operation. Int J Cardiol Congenit Heart Dis. 2022;7:100338. doi: 10.1016/j.ijcchd.2022.100338.\u003c/li\u003e\n \u003cli\u003eWitkowski M., Weeks T L, Hazen, SL. Gut microbiota and cardiovascular disease. Circ. Res. 2000; 127, 553\u0026ndash;570. doi: 10.1161/CIRCRESAHA.120.316242\u003c/li\u003e\n \u003cli\u003eGo K, Horiba K, Yamamoto H, Morimoto Y, Fukasawa Y, Ohashi N, et al. Dysbiosis of gut microbiota in patients with protein-losing enteropathy after the Fontan procedure. Int J Cardiol. 2024;396:131554. doi: 10.1016/j.ijcard.2023.131554.\u003c/li\u003e\n \u003cli\u003eWang K, Han L, Ma J, Fang Y, He Y, Liu X, et al. Gut microbiota community and metabolic profiles in direct total cavopulmonary connection and Fontan circulation: a cross-sectional study in the single center. Front Microbiol. 2025;16:1539046. doi: 10.3389/fmicb.2025.1539046.\u003c/li\u003e\n \u003cli\u003eFialho A, Fialho A, Kochhar G, Schenone AL, Thota P, McCullough AJ, et al. Association Between Small Intestinal Bacterial Overgrowth by Glucose Breath Test and Coronary Artery Disease. Dig Dis Sci. 2018;63(2):412-421. doi: 10.1007/s10620-017-4828-z.\u003c/li\u003e\n \u003cli\u003eSong Y, Liu Y, Qi B, Cui X, Dong X, Wang Y, et al. Association of Small Intestinal Bacterial Overgrowth With Heart Failure and Its Prediction for Short-Term Outcomes. J Am Heart Assoc. 2021;10(7):e015292. doi: 10.1161/JAHA.119.015292.\u003c/li\u003e\n \u003cli\u003eYoo SJ, Prsa M, Schantz D, Grosse-Wortmann L, Seed M, Kim TK, et al. MR assessment of abdominal circulation in Fontan physiology. Int J Cardiovasc Imaging. 2014;30(6):1065-72. doi: 10.1007/s10554-014-0424-x.\u003c/li\u003e\n \u003cli\u003eAngelotti A, Dhesi M, Bansal SS, Bradley EA. Novel immunologic mechanisms for Fontan-associated liver disease. Int J Cardiol Congenit Heart Dis. 2024;19:100554. doi: 10.1016/j.ijcchd.2024.100554.\u003c/li\u003e\n \u003cli\u003eMagdo HS, Stillwell TL, Greenhawt MJ, Stringer KA, Yu S, Fifer CG, et al. Immune Abnormalities in Fontan Protein-Losing Enteropathy: A Case-Control Study. J Pediatr. 2015;167(2):331-7. doi: 10.1016/j.jpeds.2015.04.061.\u003c/li\u003e\n \u003cli\u003eLona-Reyes JC, Torres-Molina S, Flores-Fong LE, Estrada-Arce EV, Rivera-Ch\u0026aacute;vez E, N\u0026uacute;\u0026ntilde;ez-N\u0026uacute;\u0026ntilde;ez ME, et al. Protein-losing enteropathy in a preschool patient with intestinal tuberculosis. Gastroenterol Hepatol. 2022;45(3):204-205. English, Spanish. doi: 10.1016/j.gastrohep.2020.08.017.\u003c/li\u003e\n \u003cli\u003eDe Boer RJ, Homann D, Perelson AS. Different dynamics of CD4+ and CD8+ T cell responses during and after acute lymphocytic choriomeningitis virus infection. J Immunol. 2003;171(8):3928-35. doi: 10.4049/jimmunol.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-gastroenterology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmge","sideBox":"Learn more about [BMC Gastroenterology](http://bmcgastroenterol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmge/default.aspx","title":"BMC Gastroenterology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Small Intestinal Bacterial Overgrowth, Fontan operation, enteropathy","lastPublishedDoi":"10.21203/rs.3.rs-7826456/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7826456/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eGastrointestinal complications, including protein-losing enteropathy (PLE) and Fontan-Associated Liver Disease (FALD) are common in the group of patients after Fontan procedure. However, the data concerned the Small Intestinal Bacterial Overgrowth (SIBO) occurrence in this group of patients are lacking. The general aim of this study was to determinate the SIBO occurrence in the group of the patients after Fontan surgery. Moreover, we focused to compare the enteropathy, immunological disturbances and SIBO diagnosis depending on the type of Fontan procedure.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis was a cross-sectional observational study (years 2021\u0026ndash;2024) including patients after Fontan procedure (study group) and healthy subjects (control group) aged 5\u0026ndash;18 years from 2 polish pediatric centers. In all subjects\u0026rsquo; laboratory tests including blood counts and biochemical parameters were performed. Additionally, in the study group the immunoglobulin serum concentrations and peripheral lymphocytes subpopulation were examined. Lactulose Hydrogen Breath Test (LHBT) was used to SIBO recognition. Enteropathy was diagnosed based on clinical and laboratory features.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThere were no differences in SIBO occurrence between study and control groups. In the group with PLE (16.2%) immunological deficiencies were found more often than in the group without enteropathy (IgG (72.73% vs. 3.51%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.00), IgA (36.36% vs. 10.53%; p\u0026thinsp;=\u0026thinsp;0.04), CD4 (100% vs. 56.14%; p\u0026thinsp;=\u0026thinsp;0.00), CD19 (45.45% vs. 14.04%; p\u0026thinsp;=\u0026thinsp;0.02). SIBO was recognized more frequently in the group after intracardiac Fontan (ICF) than extracardiac Fontan (ECF) communication (p\u0026thinsp;=\u0026thinsp;0.01) but was not associated with immunological disturbances.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThe SIBO occurrence in dependence of the type of Fontan procedure may be due to differences in the gut perfusion between ICF and ECF groups, that require confirmation in future research.\u003c/p\u003e","manuscriptTitle":"Small Intestinal Bacterial Overgrowth and Immunological Disturbances in Fontan- Associated Enteropathy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-20 08:14:45","doi":"10.21203/rs.3.rs-7826456/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-12-10T13:22:13+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-30T01:56:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192573605027987404601358721751552048732","date":"2025-11-19T02:57:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-11T12:28:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"183351926902875928650816547038852517265","date":"2025-11-11T09:29:57+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-10T20:19:18+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-16T10:26:40+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-14T00:24:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-14T00:23:30+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Gastroenterology","date":"2025-10-10T11:28:18+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-gastroenterology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmge","sideBox":"Learn more about [BMC Gastroenterology](http://bmcgastroenterol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bmge/default.aspx","title":"BMC Gastroenterology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cb2ebba7-df0e-4016-b1f5-769eef914e3d","owner":[],"postedDate":"November 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-01-08T16:08:26+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-20 08:14:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7826456","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7826456","identity":"rs-7826456","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}