The main causes of mitral stenosis are identified in rheumatic disease triggered by streptococcus bacterial infection, in senile degeneration with increased deposition of calcium salts on the cusps - especially starting from the 5th/6th decade -, in congenital heart defects (present since birth), in valve infections caused by endocarditis.
The rheumatic origin merits a note of its own: although it is much rarer in western societies (in terms of frequency) than in the past owing to the improvement in quality of life and to the use of antibiotics, in recent decades we have witnessed the return of mitral stenosis due to the ever greater migratory flows from Africa and countries where valvulopathy is still the direct outcome of the improperly treated disease.
Going back to the alteration in valve functionality, it should be stated that if we do not intervene appropriately and promptly, the defect may develop into a serious modification of the mitral geometry with the almost total welding of the leaflets, shortening and fusion of the chordae tendineae and deformation of the left ventricle.
The complications associated with stenosis can be summarized in: heart arrhythmias (first among them atrial fibrillation); left atrial thrombosis, embolisms, pulmonary oedema. In many cases, evaluated beforehand, dilation of the stenotic orifice by means of a balloon inflated inside it helps attenuate the symptoms - dyspnoea (hunger for air) first of all -; but if calcification of the valve leaflets is very advanced and there is coexistence of mitral regurgitation, the cardiac surgeon intervenes by replacing the diseased valve - chosen most often - with a biological or mechanical prosthesis or by repairing it.