Patients with mitral stenosis need to pass the blood from the atrium to the heart through the mitral valve during cardiac diastole. The narrowing condition in patients with mitral stenosis leads to an accelerated and prolonged flow of blood from the atrium to the ventricle. As a result, atrial pressure increases, and this heightened atrial pressure can cause pulmonary congestion. In severe cases, it leads to pulmonary hypertension. Pulmonary hypertension, in turn, can cause enlargement of the right ventricle and tricuspid regurgitation, which can lead to the patient exhibiting cyanosis. Therefore, in patients with mitral stenosis, the atrium gradually enlarges in the early stages, and later stages may present with right ventricular hypertrophy.