[header] How to diagnose mitral stenosis [title] Watch for shortness of breath. [step] One of the main symptoms that mitral stenosis may present with is shortness of breath-in particular, waking in the night with breathing difficulties. The shortness of breath may get worse with exertion, and/or when lying down. 
The shortness of breath is caused by decreased effectiveness of blood flow with each heartbeat, due to partial blockage of the mitral valve (called " stenosis "). [substeps] Your shortness of breath may progressively get worse with time.