Abstract 1774: Structural and Functional Uncoupling of Liver Performance in the Fontan Circulation
Background It is known that Fontan patients have widespread hepatic fibrosis and cirrhosis, but their global hepatic function is poorly understood. We hypothesized equivalent structural and functional hepatic derangement in Fontan patients and compensated non-cardiac cirrhotic patients.
Methods 21 (42% female, mean age 19±5 yrs) stable Fontan patients were prospectively compared with 8 histologically proven compensated cirrhotic (Childs A and MELD scores<10) patients. All patients had cardiac and liver histories denoted, physical examination, and echocardiography. Additionally blood was taken for a standard liver profile, “Enhanced Liver Fibrosis” (ELF) score (including hyaluronic acid, aminoterminal type III procollagen peptide P3NP and tissue inhibitor of metalloproteinase TIMP-1 levels), and then indocyanine green clearance (ICG) determined by 1 observer using the LiMON Device ™. Plasma disappearance rate (PDR) and 15 minute retention (R15) were recorded after ICG infusion.
Results The Fontan was right atrium (RA) to pulmonary artery (PA) in 16; lateral tunnel in 2; RA to right ventricle (RV) in 2 and other variant in 1. There was no difference in albumin, ALT and bilirubin levels between the Fontan and cirrhotic patients. PDR (17%/min ±5) and R15 (11% ±10) were not significantly different in Fontan patients as compared with compensated cirrhotic patients. ELF scores were similar in the Fontan and cirrhotic patients (8.3±8.2 p=NS). In the Fontan group this was highly correlated with mean RA pressures, R=0.564, p=0.01. There was a positive correlation between PDR and ELF (R=0.77, p=0.028) in the cirrhotic group but not in the Fontan group. Within the Fontan group, those with impaired ventricular function and systolic blood pressure <100 mmHg had significantly lower R15 (17% ±2, vs. 21% ±14, p=0.02) and PDR (12%/min ±4 vs 18%/min ±3, p=0.02).
Conclusions Fontan patients have similar global hepatic function and structural derangement as stable cirrhotic patients. Fontan patients exhibit dissociation between function and structure unlike in the stable cirrhotic patients where these 2 factors are highly correlated. We postulate diminished hepatic flow rather than hepatocyte dysfunction causing global hepatic dysfunction in Fontan patients.