Background and Objective

The series type of LVAD (i.e., BJUT-II VAD) is a novel left ventricular assist device, whose effects on the aortic valve remain unclear.

Methods

The biomechanical effects of BJUT-II VAD on the aortic valve were investigated by using a fluid–structure interaction method. The geometric model of BJUT-II VAD was virtually implanted into the ascending aorta to generate the realistic flow pattern for the aortic valve (i.e., support). In addition, the biomechanical states of the aortic valve without BJUT-II VAD support was computed as control (i.e., control case).

Results

Results demonstrated that the biomechanical effects of BJUT-II VAD were quite different from that resulting from traditional “bypass LVAD.” Compared with those in the control case, BJUT-II VAD support could significantly reduce the stress load of the leaflet (maximum stress, 0.5 MPa in the control case vs. 0.12 MPa in the support case). Similarly, the rapid valve opening time (100 ms in the control case vs. 175 ms in the support case) and rapid valve closing time (50 ms in the control case vs. 150 ms in the support case) in the support case were obviously longer than those in the control case. Moreover, BJUT-II VAD support reduced retrograde blood flow during the diastolic phase and significantly changed the distribution of WSS of the leaflets.

Conclusions

In summary, while unloading the left ventricle, BJUT-II VAD could provide beneficial biomechanical states for the aortic leaflets, thereby reducing the risk of aortic valve disease.

中文翻译：

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新型LVAD系列对主动脉瓣的生物力学效应。

背景与目的

LVAD的串联类型（即BJUT-II VAD）是一种新型的左心室辅助装置，其对主动脉瓣的影响尚不清楚。

方法

采用流固耦合方法研究了BJUT-II VAD对主动脉瓣的生物力学作用。实际上将BJUT-II VAD的几何模型植入升主动脉中，以生成主动脉瓣（即支撑物）的真实流动模式。另外，计算没有BJUT-II VAD支持的主动脉瓣的生物力学状态作为对照（即对照情况）。

结果

结果表明，BJUT-II VAD的生物力学效果与传统的“旁路LVAD”所产生的效果完全不同。与对照例相比，BJUT-II VAD支架可以显着降低小叶的应力负荷（最大应力，对照例为0.5 MPa，支撑例为0.12 MPa）。同样，在支持情况下，快速阀门打开时间（控制情况下为100毫秒，在支撑情况下为175毫秒）和在控制情况下的快速阀门关闭时间（控制情况下为50毫秒，在支持情况下为150毫秒）明显比对照案例更长。此外，BJUT-II VAD支持减少了舒张期的逆行血流，并显着改变了小叶WSS的分布。

结论

总之，在卸载左心室时，BJUT-II VAD可以为主动脉小叶提供有益的生物力学状态，从而降低主动脉瓣膜疾病的风险。