‘Stenosis’ suggests that a valve is abnormally stiff and therefore doesn’t open properly. The most common cause of stenosis is the buildup of calcium on a valve over time (similar to limescale) as people age. Many valves affected by calcification will still open fairly well and are therefore unlikely to cause symptoms (we call these ‘sclerotic’ valves). However, if a valve becomes severely stenosed, this will obstruct the flow of blood out of one of the heart’s chambers, which can cause shortness of breath, chest pain, and even fainting. These valves are likely to need replacing.
Some abnormally formed valves (such as a ‘bicuspid aortic valve’) are predisposed to developing stenosis; these need careful monitoring in specialist clinics.