Intraventricular flow visualization study in continuous aortic valve closure during axial flow pump support.

When the cardiac function is minimal, LVAD patients' intraventricular blood flow occurs entirely through the LVAD, the aortic valve is continuously closed, this condition significantly alters intraventricular haemodynamics and increases the risk of intraventricular thrombosis. The aim of this study was to analyse intraventricular blood flow patterns in continuous aortic closure, during axial flow pump support. In vitro flow visualization experiments inside a 3D-printed silicone LV model were conducted to emulate the intraventricular hemodynamic parameters inside the LV during LAP31 axial blood pump support, including the distribution of velocity, vorticity and the standard deviation of velocity. The results showed that the intraventricular blood flows directly from the mitral valve to the blood pump inlet at the three instants of the cardiac cycle when the aortic valve is continuously closed, and the standard deviation of the blood flow velocity in the examined cross-section was uniform. Meanwhile, the strong vorticity was observed in the ventricular wall near the blood pump inlet and below the aorta throughout the cardiac cycle, and the location of the strong vorticity region does not change over time. This phenomenon causes intraventricular blood stagnation in the left ventricular outflow tract and the ventricular wall near the blood pump inlet, which increases the risk of thrombus formation in the heart.