Purpose

Mitral regurgitation (MR) is the second most common valve disease in industrialized countries. Despite its high prevalence, little is known about its impact on the flow dynamics in the left ventricle (LV). Because of the interdependence between valvular function and hemodynamics in the heart chambers, an exploration of the dynamics in the LV could lead to a diagnosis of MR. This in vitro study aimed to develop an advanced left heart simulator capable of reproducing several conditions of MR and to evaluate their impact on the LV flow dynamics in terms of flow structures and viscous energy dissipation (VED).

Methods

A simulator, previously developed to test mechanical and biological valves, was upgraded with an original anatomically-shaped mitral valve made from a hydrogel. The valve can be used in healthy or pathological configurations. The nature and severity of the disease was controlled by applying specific strain to the chordae. In this study, in addition to a healthy condition, two different severities of MR were investigated: moderate MR and severe MR. Planar time-resolved particle image velocimetry measurements were performed in order to evaluate the velocity field in the LV and the VED induced by each condition.

Results

Our results showed that MR led to flow disturbances in the LV that were characterized by an increase in mitral inflow velocity and by elevated values of VED. Interestingly VED increased in proportion to the severity of MR and with a dissipation predominating during systole.

Conclusion

Considering these results, the introduction of new parameters based on LV VED could provide crucial information regarding the coupling between the mitral valve and the LV and allow for a better stratification of patients with MR.

中文翻译：

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二尖瓣反流对左心室模型中血流的影响

目的

二尖瓣关闭不全 (MR) 是工业化国家中第二常见的瓣膜疾病。尽管其患病率很高，但对其对左心室 (LV) 血流动力学的影响知之甚少。由于瓣膜功能和心腔血流动力学之间的相互依赖性，对 LV 动力学的探索可能会导致 MR 的诊断。这项体外研究旨在开发一种先进的左心模拟器，能够再现多种 MR 条件，并评估它们在流动结构和粘性能量耗散 (VED) 方面对 LV 血流动力学的影响。

方法

先前开发用于测试机械和生物瓣膜的模拟器升级为由水凝胶制成的原始解剖形状的二尖瓣。该瓣膜可用于健康或病理配置。该疾病的性质和严重程度是通过对脊索施加特定应变来控制的。在这项研究中，除了健康状况外，还研究了两种不同严重程度的 MR：中度 MR 和重度 MR。进行平面时间分辨粒子图像测速测量，以评估 LV 中的速度场和由每种条件引起的 VED。

结果

我们的结果表明，MR 导致 LV 的血流紊乱，其特征是二尖瓣流入速度增加和 VED 值升高。有趣的是，VED 与 MR 的严重程度成正比，并且在收缩期以耗散为主。

结论

考虑到这些结果，引入基于 LV VED 的新参数可以提供有关二尖瓣和 LV 之间耦合的关键信息，并允许对 MR 患者进行更好的分层。