Computational fluid dynamics simulations in realistic 3-D geometries of the total cavopulmonary anastomosis: the influence of the inferior caval anastomosis.

Fluid dynamics of Total Cavo-Pulmonary Connection (TCPC) were studied in 3-D models based on real dimensions obtained by Magnetic Resonance (MR) images. Models differ in terms of shape (intra- or extra-cardiac conduit) and cross section (with or without patch enlargement) of the inferior caval (IVC) anastomosis connection. Realistic pulsatile flows were submitted to both the venae cavae, while porous portions were added at the end of the pulmonary arteries to reproduce the pulmonary afterload. The dissipated power and the flow distribution into the lungs were calculated at different values of pulmonary arteriolar resistances (PAR). The most important results are: i) power dissipation in different TCPC designs is influenced by the actual cross sectional area of the IVC anastomosis and ii) the inclusion of a patch minimizes the dissipated power (range 4-13 mW vs. 14-56 mW). Results also show that the perfusion of the right lung is between 15% and 30% of the whole IVC blood flow when the PAR are evenly distributed between the right and the left lung.