Comparison of in vitro velocity measurements in a scaled total cavopulmonary connection with computational predictions.

Minimizing pressure drop through the total cavopulmonary surgical connection (TCPC), where the superior and inferior vena cavae (SVC), (IVC) are connected directly to the right and left pulmonary arteries, is an important clinical consideration. Computational fluid dynamics (CFD) models have been used to examine the impact of connection configuration on TCPC pressure drop. However, few studies have validated CFD results with experimental data. This study compares flow field measurements on two different TCPC models at varying SVC:IVC flow rate ratios using CFD and digital particle image velocimetry (DPIV). Although the primary flow fields generated by CFD and DPIV methods were similar for the majority of flow conditions, three key differences were found: (1) the CFD model did not reproduce the 3D complexity of flow interactions in the no-offset model with 50:50 flow ratio; (2) in vitro results showed consistently higher secondary flow components within the pulmonary artery segments, especially for the no-offset model; (3) recirculation areas for the 1/2 diameter offset model were consistently higher for in vitro versus CFD results. We conclude that this numerical model is a reasonable means of studying TCPC flow, although modifications need to be addressed to ensure that numerical results reproduce secondary flow characteristics.