Hemodynamic Studies Before and After Instrumental Mitral

surgery and to enhance our understanding of the pathophysiology of mitral stenosis. Although surgery produced a significant increase in calculated mitral valve area, the degree of improvement varied markedly. The younger patients had the greater increase in mitral valve area. The change in cardiac index and pulmonary vascular resistance correlated well with the change in mitral valve area. Only those patients whose mitral valve area increased over 1.0 cm2 had a significant increase in cardiac index and a fall in pulmonary vascular resistance. The data indicate that the reduced cardiac index and elevated pulmonary vascular resistance in patients with mitral stenosis are related to the mitral valve obstruction and are at least in part reversible and that the elevated pulmonary vascular resistance during mild exercise is related to elevated left atrial