Aghilinejad Arian, Bilgi Coskun, Geng Haojie, Pahlevan Niema M
Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA.
Department of Aerospace & Mechanical Engineering, University of Southern California, Los Angeles, CA, USA.
J R Soc Interface. 2025 Feb;22(223):20240887. doi: 10.1098/rsif.2024.0887. Epub 2025 Feb 19.
Wave propagation in the heart tube is key to establishing an early pumping mechanism, as explained by impedance pump theory in zebrafish. Though initially proposed for embryonic blood circulation, the role of impedance-like behaviour in the mature cardiovascular system remains unclear. This study focuses on the understudied physiological mechanism of longitudinal displacement in the adult aorta caused by the long-axis motion of the heart. Using magnetic resonance imaging on 159 individuals, we compared aortic displacement profiles between a control group and those with heart failure, revealing a significant difference in aortic stretch between the two groups. Building on this clinical evidence, we conducted experiments to isolate the effects of longitudinal aortic wave pumping by eliminating the pumping action of the heart. We identified three biomechanical properties of stretch-related longitudinal wave pumping that exhibit characteristics like impedance pump: (i) a nonlinear flow-frequency relationship, (ii) bidirectional flow, and (iii) the potential for both positive and negative flow at a fixed frequency, contingent upon the aorta's wave speed dictating the wave state. Our results demonstrate for the first time that this mechanism generates a significant flow, potentially providing a supplementary pumping mechanism for the heart.
正如斑马鱼阻抗泵理论所解释的那样，心脏管中的波传播是建立早期泵血机制的关键。尽管最初是针对胚胎血液循环提出的，但类似阻抗行为在成熟心血管系统中的作用仍不清楚。本研究聚焦于成年主动脉中由心脏长轴运动引起的纵向位移这一尚未充分研究的生理机制。我们对159名个体进行了磁共振成像，比较了对照组和心力衰竭患者的主动脉位移情况，发现两组之间的主动脉伸展存在显著差异。基于这一临床证据，我们进行了实验，通过消除心脏的泵血作用来分离主动脉纵向波泵血的影响。我们确定了与伸展相关的纵向波泵血的三种生物力学特性，这些特性表现出类似阻抗泵的特征：（i）非线性流量-频率关系，（ii）双向流动，以及（iii）在固定频率下，根据主动脉波速决定波状态，存在正向和负向流动的可能性。我们的结果首次证明，这种机制会产生显著的流量，可能为心脏提供一种补充泵血机制。
