Fluid Dynamic and Hemodynamic Characterization of Flow in a Left Ventricular Assist Device

Left Ventricular Assist Devices (LVADs) are implantable mechanical circulatory support systems designed for patients with end-stage heart failure. LVAD flow dynamics affect efficiency and hemocompatibility, requiring analysis for better design. An in vitro experimental platform was developed to characterize the hemodynamic performance of an LVAD. The LVAD housing and impellers were precision-machined from acrylic using CNC milling at the Georgia Tech Machine Shop. The integrated flow loop included a fluid reservoir, high-fidelity pressure transducers, a flow probe, and a downstream resistance valve to control afterload conditions. A 40%wt glycerin-water solution was used to match the viscosity of blood. The rotor was driven by a programmable motor, and flow dynamics were measured using a double-pulsed Particle Image Velocimetry (PIV) system (LaVision FlowMaster). Illumination was provided by a 527 nm Nd:YLF laser, and particle images (1–20 µm seeding particles) were captured by a high-speed CMOS camera (Photron FastCam). Time-Resolved and Phase-locked PIV measurements were acquired at multiple rotational speeds (1000–3000 RPM) to resolve velocity fields. Detailed flow patterns were analyzed including regions of recirculation, and high-velocity shear layers near the impeller blades and diffuser. Post-processing included derivation of velocity gradients and shear stress fields, enabling assessment of blood damage-related parameters under varying hydraulic loads.