Pangelina Chaztyn, Vu Vi, May-Newman Karen
From the Department of Mechanical Engineering, Bioengineering Program, San Diego State University, San Diego, California.
ASAIO J. 2025 Feb 1;71(2):149-156. doi: 10.1097/MAT.0000000000002298. Epub 2024 Aug 27.
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.
主动脉窦中形成的涡流在优化血流方面起着至关重要的作用。涡流的破坏会导致血流停滞，并激活主动脉根部的血栓形成，尤其是在左心室辅助装置（LVAD）支持期间主动脉瓣血流减少时。我们在本研究中的目标是在主动脉根部的实验模型中，随着血流逐渐减少，观察涡流的形成。一个模拟循环回路与HeartMate II LVAD相结合，该循环回路可再现心力衰竭血流动力学，并在带有生物瓣膜的透明主动脉根部测量流速。在基线以及所有有血流通过主动脉瓣的情况下，主动脉瓣窦涡流在速度场中作为反向旋转结构清晰可见。随着LVAD速度增加，中心射流变窄，但涡流持续存在，仅在瓣膜完全关闭时才消失。涡流保持流体动量，并在组织表面产生剪切应力，从而破坏血流停滞。这些特征强调了按照推荐为LVAD患者维持“间歇性”主动脉瓣开放的重要性。本研究首次报告了LVAD支持期间主动脉根部的涡流形成，为进一步评估提供了动力。
