a condition in which one of the heart valves (= flaps that control the flow of blood) does not open or close properly, causing extra strain on the heart

Heart valve disease may be due to heart abnormalities at birth, infection, or degeneration with age. 心脏瓣膜病可能是因为出生时即有的异常、感染或是因衰老导致的功能减退造成。