来自《耶鲁大学开放课程：生物医学工程探索第25集第25集》

there's an obstacle to

这种阻碍血流的障碍物
blood flow creates an additional resistance.

就产生了额外的血流阻力
Your heart has to work harder

而绕过这个位于中心的巨大球体
in order to overcome the resistance of the flow

所产生的额外血流阻力
going around this large ball that's in the center.

需要由你的心脏通过更努力的工作来克服
It works well as a valve but it's not a very efficient valve,

这种人工瓣膜能起到效果但效率很低
in that it requires your

需要你的心脏
heart to work more to get a certain flow rate

做额外的功来保证血流速度
because it's blocking--

因为它阻塞了
this ball is blocking the center of the flow.

这个球阻塞了中央血流
In addition, you can imagine this ball

另外你能想象
slamming up and then slamming back down.

这个小球上下拍击