Predictive Embolic Trajectory Mapping of Ventricular Assist Device Outflow

A left ventricular assist device (LVAD) is a mechanical pump that provides circulatory support as a bridge-to-cardiac transplantation in patients with advanced heart failure. A potential adverse event of LVAD support is thrombus ingestion or formation, which may then travel through the device into the cerebral arteries, causing ischemic strokes. It has been previously demonstrated (mostly numerical in nature) that the graft geometrical parameters can affect the trajectories of particles. In this in-vitro study, we expand and verify such a hypothesis in a refractive-index-matched time-resolved particle tracking velocimetry (PTV) system. For this purpose, four patients with implanted LVADs are recruited. In addition to the existing cannula configurations, two other anastomosis angles with a comparable curvature and location are considered. Thin-wall phantoms of such models are 3D-printed with precision and placed in a flow loop providing physiological flow conditions. Precision fluorescent beads ranging from 0.02 to 1.0 mm are used to replicate emboli at two clinically relevant flow rates, spanning over 100 experimental cases combined. This systematic study identifies the optimal graft candidate that reduces the number of thrombi-replicating particles reaching cerebral vessels.