They can produce a "ballvalve" effect by intermittently occluding the atrioventricular valve orifice.
他们可以产生“球阀”效应，引起房室瓣口间歇性关闭。
2
Introducing the sealing principle of fixed ballvalve and the calculation of seat sealing force, analyzing the effect of machining error upon sealing property and putting forward improving opinions.