Flow visualization techniques in a mock ventricle supported by a nonpulsatile left ventricular assist device

Little is known about flow patterns in ventricles supported by continuous flow left ventricular assist devices (LVADs), and valuable information can be obtained with simple flow visualization experiments. We describe the application of several experimental techniques for the in vitro study of ventricular flow patterns (e.g., unsteadiness, vortical motions, stagnation regions) in the presence of a continuous flow LVAD. We used dye streaks, particle paths, and hydrogen bubble techniques to visualize fluid flow in an idealized, static, transparent mock ventricle attached to a Jarvik 2000 continuous flow LVAD. We recorded ventricular flow behavior at various pump speeds while independently adjusting pump flow (by varying the afterload) to emulate in vivo pump flow at various phases of the cardiac cycle. Changes in ventricular flow behavior at different pump flow rates may be of clinical relevance, because continuous flow pumps are extremely sensitive to inflow and outflow pressures and instantaneous pump flow varies significantly at different points throughout the cardiac cycle. Further work is needed to quantitatively compare the flow behavior of different continuous flow devices in a pulsatile ventricular model.