Purpose

The objective of this study was to develop a novel single opening&closing pulsatile flow in-vitro valve tester for direct measurement of closing volume of the heart valve.

Methods

A single opening&closing valve tester was composed of a piston pump, valve mounting chamber, reservoir, measurement and control system. The piston pump was used to drive a valve to open and close with dictated flow which comprised three phases of accelerated, constant, and decelerated flow with six slopes. A high speed camera was used to record valve opening and closing images. Two pressure transducers across the tested valve were used to capture the ending time of valve closing which was verified by the high-speed photography. The closing time was measured and closing volume was calculated with a piston displacement volume during valve closing. A tilting disc valve and porcine mitral valve were tested.

Results

There was a big difference in flowrate between the Transonic flowmeter and piston pump. The heart valve opened and closed under the dictated flow driven by the piston pump. The transvalvular pressure was minor during valve opening and then increased sharply during valve closing. The closing time varied approximately linearly with the slope of the decelerated flow and was comparable between the two methods by the transvalvular pressure and high-speed photography. The closing volumes did not change much with the slope of the decelerated flow and were 7.0 ± 1.0 and 14.0 ± 1.5 mL for the tilting disc valve and mitral valve, respectively.

Conclusion

Pulsatile flow is challenging to the flowmeter. A novel single opening&closing pulsatile flow in-vitro valve tester for the heart valve has successfully been developed and can be used to simulate and evaluate the opening and closing hemodynamics of the heart valve. The tester can be used to measure valve closing volume and time accurately with a standardized testing protocol free from effect of other components such as the resistance, compliance units and auxiliary valve in the continuous pulsatile flow valve tester.

中文翻译：

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一种直接测量心脏瓣膜关闭容积的单开闭阀测试仪

目的

本研究的目的是开发一种新颖的单开闭式脉动流体外瓣膜测试仪，用于直接测量心脏瓣膜的闭合体积。

方法

单开闭阀测试仪由活塞泵、阀门安装室、油箱、测控系统组成。活塞泵用于驱动阀门以指定的流量打开和关闭，该流量包括三个阶段的加速、恒定和减速流，具有六个斜率。使用高速摄像机记录阀门打开和关闭的图像。测试阀门两端的两个压力传感器用于捕捉阀门关闭的结束时间，并通过高速摄影验证。测量关闭时间并用阀门关闭期间的活塞位移体积计算关闭体积。测试了倾斜盘瓣和猪二尖瓣。

结果

Transonic流量计和活塞泵之间的流量差异很大。心脏瓣膜在活塞泵驱动的指令流量下打开和关闭。在瓣膜打开期间跨瓣压力较小，然后在瓣膜关闭期间急剧增加。关闭时间与减速流的斜率大致呈线性变化，并且通过跨瓣压力和高速摄影在两种方法之间具有可比性。关闭体积随减速流的斜率变化不大，倾斜盘阀和二尖瓣的关闭体积分别为 7.0 ± 1.0 和 14.0 ± 1.5 mL。

结论

脉动流对流量计具有挑战性。研制成功一种新型单开闭式脉动流体外瓣膜试验仪，可用于模拟和评价心脏瓣膜的开闭血流动力学。该测试仪可用于通过标准化的测试协议准确测量阀门关闭体积和时间，不受连续脉动流量阀门测试仪中的阻力、顺应性单元和辅助阀门等其他组件的影响。