[Clinico-physiological assessment of the mechanisms of compensation and paracompensation in patients with mitral stenosis].

The paper presents the results of an examination of 292 patients with Stages II-V mitral stenosis. Clinical, roentgenological, and electrocardiographic characteristics of the defect were analysed. Physical fitness and gas exchange during exercise were studied in 183 patients with Stages III and IV mitral stenosis. The findings were compared with the intensity of tissue oxygen exchange and the levels of myocardial myoglobin. The patients with mitral stenosis exhibited lower exercise tolerance that was more pronounced in Stage IV. The patients also displayed characteristic profound disturbances in work energy regimen, lower reserve potentialities and functional mobility of the cardiorespiratory system. The pronounced changes in the acid-base balance and gas composition of their capillary blood in Stage IV mitral stenosis during exercise may be explained by a sharply marked arteriolar barrier in the pulmonary circulation (a paracompensatory reaction). The comparison of physiological and clinical findings has enabled the relationship of mechanisms responsible for compensation and paracompensation to be evaluated at various stages of mitral stenosis.