What is Congenital Mitral Stenosis ?

The onset of symptoms or signs depends on severity of the stenosis, severe the stenosis earlier the presentation. With significant MS, the LA becomes dilated and hypertrophied. The LA pressure increases which then raises pulmonary venous and capillary pressures. High LA pressure results in a high-pressure gradient between the LA and LV during diastole, giving rise to mid-diastole rumble best heard at apex. There is pre-systolic accentuation due to atrial contraction in late diastole, thus increasing pressure gradient. Loud S 1 due to wide-open mitral valve at the onset of systole as a result of atrial contraction.

Murmur is preceded by an opening snap when valve cusps are mobile. The high pulmonary capillary pressure results in reflex arteriolar constriction, causing PAH and RV hypertrophy.