Evolving Hemodynamics in Fontan Circulation: Age-Driven Insights in Patients with Interrupted Inferior Vena Cava and Hepatoazygos Shunt.

Patients with interrupted inferior vena cava (I-IVC) and azygos continuation who undergo Fontan completion via hepatoazygos shunting (HAS) exhibit unique hemodynamic challenges.

This study evaluates age-related shifts in systemic venous return dominance, hepatic flow distribution (HFD), power loss (PL), and flow disturbances using patient-specific computational fluid dynamics (CFD).

Data analysis from 95 I-IVC patients showed a non-linear shift in upper-to-lower body systemic flow dominance with ratios of 2, 1, and 0. 5 (correlating to ages ~3, ~10, and ~20 respectively).

CFD simulations for 17 selected patients revealed a trend of increasing HFD toward the right pulmonary artery (RPA), with median splits of 45%-49%, 48%-52%, and 40%-60% for the respective flow ratios. Power loss increased significantly with lower-body flow dominance.

Median values for absolute PL were 4. 75 mW (ratio 2), 16. 5 mW (ratio 1), and 33. 7 mW (ratio 0. 5). Indexed PL showed a similar trend, rising from 0. 04 mW/m² to 0. 11 mW/m² across the flow ratios.

Vorticity (VOR) and viscous dissipation rates (VDR), key metrics of flow disturbances, also increased with lower-body flow dominance, showing strong correlations with PL (R = 0. 58-0. 76).

Kruskal-Wallis based statistical analysis identified significant statistical differences in absolute PL (p = 0. 0045) and flow disturbances (p < 0. 001), emphasizing the impact of age-related flow dynamics on Fontan efficiency.

Our findings emphasize the need for targeted interventions in patients with I-IVC with azygos continuation to mitigate evolving hemodynamic inefficiencies and optimize Fontan outcomes during critical growth periods.