Progression in Fontan conduit stenosis and hemodynamic impact during childhood and adolescence.
To characterize changes in Fontan conduit size over time and determine if cross-sectional area (CSA) affects cardiac output, pulmonary artery growth, and exercise capacity.We conducted a retrospective cross-sectional study of patients with Fontan physiology who underwent cardiac magnetic resonance imaging or cardiac catheterization between January 2013 and October 2019. We collected Fontan and pulmonary artery measurements, hemodynamic data, and cardiopulmonary exercise test data. We identified 158 patients with an extracardiac Fontan. We measured minimum and mean Fontan conduit CSA and assessed whether these correlated with Nakata index, cardiac index, or exercise capacity.Minimum Fontan CSA decreased by a median of 33% (24%, 40%) during a mean follow-up of 9.6 years. Median percentage decrease in Fontan CSA did not differ among 16-, 18-, and 20-mm conduits (P = .29). There was a significant decrease in the minimum Fontan CSA (33% [25%, 41%]) starting less than 1-year post-Fontan. Median Nakata index was 177.6 mm2/m2 (149.1, 210.8) and was not associated with Fontan CSA/BSA (ρ = 0.09, P = .29). Fontan CSA/BSA was not associated with cardiac index (ρ = -0.003, P = .97). A larger Fontan CSA/BSA had a modest correlation with % predicted oxygen consumption (ρ = 0.31, P = .013).Fontan conduit CSA decreases as early as 6 months post-Fontan. The minimum Fontan CSA/BSA was not associated with cardiac index or pulmonary artery size but did correlate with % predicted peak oxygen consumption.