Objective

The objective of this study is to evaluate the impact of superhydrophobic coating on the hemodynamics and turbulence characteristics of a bileaflet mechanical valve in the context of evaluating blood damage potential.

Methods

Two 3D printed bileaflet mechanical valves were hemodynamically tested in a pulse duplicator under physiological pressure and flow conditions. The leaflets of one of the two valves were sprayed with a superhydrophobic coating. Particle Image Velocimetry was performed. Pressure gradients (PG), effective orifice areas (EOA), Reynolds shear stresses (RSS) and instantaneous viscous shear stresses (VSS) were calculated.

Results

(a) Without SH coating, the PG was found to be 14.53 ± 0.7 mmHg and EOA 1.44 ± 0.06 cm². With coating, the PG obtained was 15.21 ± 1.7 mmHg and EOA 1.39 ± 0.07 cm²; (b) during peak systole, the magnitude of RSS with SH coating (110Pa) exceeded that obtained without SH coating (40 Pa) with higher probabilities to develop higher RSS in the immediate wake of the leaflet; (c) The magnitudes range of instantaneous VSS obtained with SH coating were slightly larger than those obtained without SH coating (7.0 Pa versus 5.0 Pa).

Conclusion

With Reynolds Shear Stresses and instantaneous Viscous Shear Stresses being correlated with platelet damage, SH coating did not lead to their decrease. While SH coating is known to improve surface properties such as reduced platelet or clot adhesion, the relaxation of the slip condition does not necessarily improve overall hemodynamic performance for the bileaflet mechanical valve design.

中文翻译：

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超疏水性对双叶机械心脏瓣膜流体动力学的影响。

目的

这项研究的目的是在评估潜在血液损害的情况下，评估超疏水涂层对双叶机械瓣膜血流动力学和湍流特性的影响。

方法

在生理压力和血流条件下，在脉冲复制器中对两个3D打印的双叶机械瓣膜进行了血流动力学测试。用超疏水涂层喷涂两个瓣膜之一的小叶。进行粒子图像测速。计算了压力梯度（PG），有效孔口面积（EOA），雷诺剪切应力（RSS）和瞬时粘性剪切应力（VSS）。

结果

（a）没有SH涂层，发现PG为14.53±0.7mmHg，EOA为1.44±0.06cm ²。通过涂覆，获得的PG为15.21±1.7mmHg，EOA为1.39±0.07cm ²；（b）在峰值收缩期，带有SH涂层的RSS的幅度（110Pa）超过了没有SH涂层的RSS的幅度（40 Pa），并且具有较高的可能性，即在小叶紧随其后会形成更高的RSS；（c）用SH涂层获得的瞬时VSS的幅度范围略大于不使用SH涂层获得的瞬时VSS的幅度范围（7.0 Pa对5.0 Pa）。

结论

由于雷诺剪切应力和瞬时粘性剪切应力与血小板损伤相关，SH涂层并未导致其下降。虽然已知SH涂层可以改善表面性能，例如减少血小板或血凝块的附着力，但对于双叶机械瓣膜设计，滑动条件的松弛并不一定会改善整体血液动力学性能。