Relative ventilation and perfusion of left versus right lung in mitral stenosis

Abstract

We measured relative ventilation, perfusion and ventilation/perfusion ratio of the left versus the right lung using a radioactive xenon method in 15 seated patients with mitral stenosis. The relative ventilation/perfusion ratio of the left lung was significantly less in these patients than in 11 normal subjects and there was a significant negative correlation between the ventilation/perfusion ratio of the left lung and pulmonary intravascular pressure. There was little difference between relative perfusion of the two lungs, and the reduced ventilation/perfusion ratio of the left lung seems to be mainly due to relative hypoventilation, perhaps the result of compression or distortion of the left main stem bronchus. None of the patients had more than a slight reduction in the ventilation/perfusion ratio of the left lung, and it is not likely that between lungs differences in regional function significantly affect the efficiency of gas exchange. We found no significant correlation between the relative ventilation/ perfusion ratio of the left lung and pulmonary intravascular pressure in 10 patients with mitral stenosis studied in the supine position.