Aortic Root Vortex Formation During Left Ventricular Assist Device Support.

Abstract

The vortex that forms in the aortic sinus plays a vital role in optimizing blood flow. Disruption of the vortex can result in flow stagnation and activate thrombus formation in the aortic root, especially when aortic valve flow is reduced as during left ventricular assist device (LVAD) support. Our goal in this study was to visualize vortex formation in an experimental model of the aortic root as flow is progressively reduced. A mock circulatory loop that reproduces heart failure hemodynamics was combined with a HeartMate II LVAD and velocity measured in a transparent aortic root with a bioprosthetic valve. The aortic valve sinus vortices are clearly visible as counter-rotating structures in the velocity field at baseline and for all conditions with flow through the aortic valve. As LVAD speed increases, the central jet narrows but the vortices persist, disappearing only when the valve is completely closed. The vortices preserve fluid momentum and generate shear stress along the tissue surfaces which disrupts flow stasis. These features underscore the importance of maintaining "intermittent" aortic valve opening, as recommended for LVAD patients. This study is the first to report vortex formation in the aortic root during LVAD support, providing a motivation for further evaluation.