Hemolysis quantification for single ventricles undergoing the stage I (Norwood) operation*

The Norwood procedure is a lifesaving surgical operation performed on newborns suffering from hypoplastic left heart syndrome (HLHS). This operation involves the insertion of a shunt to create a parallel circulation between systemic and pulmonary circuits. The blockage of the established circulation is fatal, accounting for a large portion of complications in these patients. As the first step to understanding such complications, we adopt a multiscale model in this study to predict hemolysis in a set of idealized models. For this purpose, we use our in-house CFD solver coupled with cell-resolved Lagrangian models of red blood cells (RBCs) to measure stresses and strains on the RBC membrane for quantifying the RBC damage and, in extreme cases, rupture caused by this surgery. In total, we simulated three anatomies including 2.5mm and 4.0mm diameter Blalock-Taussig (BT) shunts and a 2.5mm central shunt, with 2000 RBCs in each case. Using maximum strain as an indicator of hemolysis, the results suggest that the shunt configuration has a larger effect on the RBC damage than changing the shunt size, with a larger diameter shunt being more prone to hemolysis. Overall, the central shunt creates the highest areal and shear strains on RBCs' surface, indicating that it is a riskier option in comparison to the BT shunt in terms of hemolysis.