人造生物瓣膜的英文：
BPV, bioprosthetic valve

valve是什么意思：
n. 阀门；瓣膜；真空管
v. 装阀于；以活门调节

Valve Disadvantages: The valve is difficult to close and requires the operator to double close the valve.
阀门的缺点:阀门难以关闭，要求操作者二次关闭阀门。

pilot valve governor
带伺服电动机的调节器辅助调速器

The valve has jammed shut.
阀门给卡住了打不开。