11.3 Hemodynamics of Mitral Stenosis

Mitral stenosis causes inflow obstruction of the left ventricle. Pressure in the left atrium is elevated and there is a gradient between the left ventricle and the left atrium. The severity of mitral stenosis and the patient's symptoms are related to the magnitude of the gradient and the pressure in the left atrium.

Gradients are strongly related to cardiac output. Therefore, gradients may rise significantly during exercise and in other hyperdynamic states.

Elevated left atrial pressure eventually translates into the pulmonary capillaries, causing post-capillary pulmonary hypertension, pulmonary congestion, and pulmonary edema. Pulmonary hypertension may lead to right heart dilatation and right heart failure. Right ventricular dilatation is associated with tricuspid annular dilation, which may ultimately result in tricuspid regurgitation. In general, the incidence of moderate to severe tricuspid regurgitation is high in the setting of mitral stenosis.
Tricuspid regurgitation in rheumatic heart disease may not only be caused by annular dilatation (in which the tricuspid valve is structurally normal) but also when the tricuspid valve is directly affected by rheumatic heart disease.

Tricuspid regurgitation in patients with mitral stenosis can also be caused by primary tricuspid valve involvement of rheumatic heart disease

Pressure tracings of the left ventricle and the left atrium in mitral stenosis. Note that a gradient is present during diastole (shaded area).