P12: Investigation of Ventricular Assist Device Inflow Configurations Within Single Ventricle Hearts

Abstract

Study: Ventricular assist devices (VADs) provide cardiac support to failing hearts. A recent study showed that over half of VAD inflow cannulas are malpositioned; this number is estimated to be greater in patients with congenital heart defects. VAD malpositioning can lead to thrombus formation (clotting), pump failure, or even patient death. The relationship between VAD inflow cannula configuration and thrombus formation was explored for a pediatric patient with a single systemic ventricle. Methods: A post-Fontan hypoplastic left heart syndrome pediatric patient was evaluated. Computational fluid dynamics (CFD) was used to investigate the potential for thrombus formation in the apical vs. diaphragmatic inflow cannula configurations. A dynamic, non-Newtonian Carreau model was used and thrombogenic potential was defined by fluid with low velocity, low strain, and long residence times. CFD was validated using particle image velocimetry (PIV) and a mock circulatory loop with a moving ventricular sac. Results: While regions with thrombogenic potential were found in both the diaphragmatic and apical cannula configurations, the apical position exhibited a greater volume of fluid with these characteristics. PIV also confirmed these results. Conclusions: Although low velocity, low strain, long residence time flow may be indicative of thrombogenic potential, many factors actually contribute to thrombus formation and should be taken into account when comparing VAD implant configurations. Furthermore, while PIV validated overall trends observed in CFD, specific numerical values differed, suggesting the need for future refinement of both the CFD and PIV models.