[Pulmonary gas exchange after myocardial infarction in the late period of recovery. II. Investigations during exercise (author's transl)].

After myocardial infarction in the late period of recovery (13-25 months p. infarctum) pulmonary gas exchange in 23 patients was measured besides as hemodynamic parameters during exercise. The parameters take a course similar to that of subjects without lung and heart diseases. Arterial blood gas tensions (Pa02, Paco2) remain unchanged compared to resting values. Alveolar ventilation did show no difference in any of the patients. Minute ventilation VE, the various dead spaces, alveolar-arterial gas differences (AaDo2, aADco2) and ventilation-perfusion ratios of the whole lung VA/Q suggest however that these parameters show different courses according to the physical capacity of the patients. As the physical capacity of each patient is due to different cardiac functions taken by cardiac output and mixed venous blood gas tensions alterations of pulmonary gas exchange seemed to be dependent on the respective left ventricular function of the heart. Of the twenty-three patients, twelve with cardiac failure under exercise showed the most pronounced alterations in pulmonary gas exchange. Therefore, the different physical work capacity of the patients are determined only by cardiac function. No limitation of the productivity due to impeded lung function could be proved.