Q. Pathophysiology of mitral stenosis?

Normally there is no pressure gradient between left atrium and the left ventricle during diastole. However, as the valve orifice size decreases pressure gradient develops across mitral valve in diastole and the mean left atrial pressure increases. Increase in left atrial pressure would cause increase in the pulmonary artery wedge pressure. Increase in pulmonary artery wedge pressure would cause interstitial congestion by way of Starling's forces and this presents as symptoms of dyspnoea. Further rise in pulmonary artery wedge pressure causes pulmonary edema and pulmonary arterial hypertension. In some patients there will be disproportionate rise in pulmonary artery pressure due to vasoreactivity of pulmonary arteries. As the pulmonary artery systolic pressure increases further the right ventricle fails and features of right heart failure would ensue.