[Multiorgan malfunction after Fontan operation in adult patients]

Although 85% of patients with univentricular heart after Fontan procedure survive twenty years after operation, the procedure alone seems to be an inadequate treatment as a permanent clinical solution. Patients with a "Fontan physiology" additionally have to face a various extra-cardiac complications, including thyroid, liver and kidney dysfunction, which are not only potentially life-threatening, but also can potentiate the circulatory insufficiency.

The aim of the study was to assess a multiorgan dysfunction in adult patients after Fontan operation in long term follow-up and compare to healthy controls.

54 patients after Fontan procedure (age=25.1±7 years, time after operation =19.8±6.3 years, age at the time of the procedure =5.3±4.3 years) and 30 controls (26.2±5.8 years) were included to the study. Clinical and laboratory examinations were performed including: hematologic, hepatic, renal and thyroid function tests. The following laboratory tests were performed: red blood cell counts (RBC), hematocrit (Ht), hemoglobin (Hb), platelets count, red blood cell distribution width (RDW), iron level; Btype natriuretic peptide (NT-proBNP), proteinogram blood test, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gammaglutamyl transpeptidase (GGTP), alkaline phosphatase (ALP), total bilirubin, alpha fetoprotein (AFP) level. Furthermore creatinine level; cystatin C, urine albumin to creatynine ratio (ACR) and urinalysis were assessed. To assess a thyroid function free triiodothyronine (fT3), free thyroxine (fT4) and thyroid stimulating hormone (TSH) were measured. Furthermore an abdomen ultrasonography was performed.

In terms of the hematological disorders Fontan patients had a statistically significant higher level of RBC (5.6±0,8 vs 4.8±0.4 109/μl; p<0,001), Hb (16.5±2.8 vs 14.2±1.2 g/dl; p<0,001), HCT (48.7±8.1 vs 42.1±3 %; p<0,001), RDW (14±2.6 vs 12.8±0.5 %; p=0.001), as compared to control group, while PLT level was statistically lower in Fontan group (156.2±61.4 vs 224.2±48 103/μl; p<0,0001). Hepatic parameters in Fontan patients were statistically significant higher, as depicted by the level of: ALT (28.5±10.5 vs 21.5±6 U/l, p<0,001), GGTP (85.6±48.8 vs 19.3±9 U/ l, p<0,001), total bilirubin (26.6±24.8 vs 8.9±4.7 μmol/l; p<0,001), ALP (82.4±31.5 vs 51.2±16 U/l; p<0,001) and INR (1.21±0.3 vs 0.98±0.2; p<0,001). Other parameters such as: AFP, total protein and albumin level did not statistically significantly differ. Additionally five patients (9%) according to clinical symptoms and serum albumin level were diagnosed protein-losing enteropathy (PLE). There was no difference in serum creatinine level between Fontan patients and control group (79.6±23.6 vs 75.9±18.9 μmol/l; p=0.8) as well as in uric acid level (342.7±102 vs 303±105 μmol/l; p=0.2). Cystatin C level was significantly higher in Fontan group in comparison to controls (1.1±0.6 vs 0.8±0.1 ng/ml; p=0,05). Furthermore four Fontan patients (7%) had abnormal microalbumin/creatynine ratio. Urine testing preformed in 30 Fontan patients pointed to 7 cases (23%) where hematuria was observed, while proteinuria was detected in 4 cases (13%) and urobilinogen in 2 (7%). Dysfunction of the thyroid gland was found in 30% of patients after Fontan operation (7% in the control group, p=0,034). Among disorders of the thyroid gland: 13% of patients were diagnosed with hyperthyroidism, 54% diagnosed with subclinical hypothyroidism, and the remaining 33% with hypothyroidism.

Our study show that adult patients after Fontan procedure in long-term follow are exposed to multiorgan complications including hematological, liver, kidney and thyroid dysfunction.