Purpose

Aortic valve replacement remains the only viable solution for symptomatic patients with severe aortic valve stenosis. Despite their improved design and long history of successful operation, bileaflet mechanical heart valves are still associated with post-operative complications leading to valve dysfunction. Thus, the flow dynamics can be highly disturbed downstream of the dysfunctional valve.

Methods

In this in vitro study, the flow dynamics downstream of healthy and dysfunctional bileaflet mechanical heart valves have been investigated using particle image velocimetry measurements. Proper orthogonal decomposition of the velocity field has been performed in order to explore the coherent flow features in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve.

Results

The ability of proper orthogonal decomposition derived metrics to differentiate between heathy and dysfunctional cases is reported. Moreover, reduced-order modeling using proper orthogonal decomposition is thoroughly investigated not only for the velocity field but also for higher order flow characteristics such as time average wall shear stress, oscillatory shear index and viscous energy dissipation.

Conclusion

Considering these results, proper orthogonal decomposition can provide a rapid binary classifier to evaluate if the bileaflet mechanical valve deviates from its normal operating conditions. Moreover, the study shows that the size of the reduced-order model depends on which flow parameter is required to be reconstructed.

中文翻译：

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功能失调的双叶机械主动脉瓣下游流动的正确正交分解分析

目的

对于有症状的严重主动脉瓣狭窄患者，主动脉瓣置换术仍然是唯一可行的解​​决方案。尽管双叶机械心脏瓣膜经过改进的设计和成功手术的悠久历史，但仍与导致瓣膜功能障碍的术后并发症有关。因此，功能失调的阀门下游的流动动力学可能会受到严重干扰。

方法

在这项体外研究中，使用粒子图像测速测量研究了健康和功能失调的双叶机械心脏瓣膜下游的流动动力学。已对速度场进行了适当的正交分解，以便在存在功能失调的双叶机械心脏瓣膜的情况下探索升主动脉中的连贯流动特征。

结果

报告了适当的正交分解衍生指标区分健康和功能障碍病例的能力。此外，使用适当的正交分解的降阶建模不仅针对速度场而且针对高阶流动特性（如时间平均壁面剪应力、振荡剪切指数和粘性能量耗散）进行了彻底研究。

结论

考虑到这些结果，适当的正交分解可以提供一个快速的二元分类器来评估双叶机械瓣是否偏离其正常工作条件。此外，研究表明，降阶模型的大小取决于需要重建的流动参数。