Cross-Sectional Area Changes in the Total Cavopulmonary Connection Pathway and Its Impact on Liver Fibrosis

Background/Objectives: A known disadvantage of extracardiac Fontan is the absence of growth potential and potential late flow stagnation compared to lateral tunnel Fontan. This study investigates the differences in changes in the cross-sectional area and impact on liver fibrosis. Methods: The anteroposterior and lateral diameters of the Fontan pathways were measured using angiograms. Cross-sectional area and the indexed cross-sectional area were calculated, and their relation to Fibrosis-4 index was analyzed. Results: A total of 334 angiograms of 224 patients (212 extracardiac and 12 lateral tunnel Fontan) were evaluated. The median age at Fontan was 2.2 (Interquartile Range: 1.8-2.9) years. The median period from Fontan to angiogram was 3.3 (0.04-10.8) years. Cross-sectional areas remained unchanged in extracardiac Fontan patients and increased in lateral tunnel Fontan patients. The indexed cross-sectional areas in extracardiac Fontan patients decreased over time. The smallest indexed-cross-sectional areas were 200 mm²/m² in extracardiac Fontan patients at 10 years postoperatively, whereas indexed cross-sectional areas in lateral tunnel Fontan patients were larger and more variable. Fibrosis-4 index increased time-dependently in both groups. Indexed cross-sectional area at the smallest level <156 mm²/m² was identified as a risk factor for liver fibrosis. Conclusions: The Fontan pathway expanded in patients after lateral tunnel Fontan, whereas indexed cross-sectional area decreased over time after extracardiac Fontan. Importantly, in patients after extracardiac Fontan, narrowing of the Fontan pathway might be one of the risk factors for progression of liver fibrosis.