[Exercise testing in cardiac patients].

Symptom-limited incremental exercise tests have been used, to estimate the severity of cardiovascular disease and the patients' daily activity. However, there is a considerable amount of interest in obtaining submaximal measurements of aerobic function rather than parameters requiring maximal exercise effort. We compared the parameters obtained during the incremental exercise with those during the 6 minutes of moderate constant work rate exercise. Peak oxygen uptake (VO2) and the anaerobic threshold were significantly decreased in patients with cardiovascular disease as compared to normal subjects. The slope of the increase in carbon dioxide output (VCO2) to the increase in VO2 (delta VCO2/delta VO2) above the anaerobic threshold was significantly increased and the slope of the increase in VO2 to the increase in work rate (delta VO2/delta WR) was significantly decreased in patients with cardiovascular disease. The anaerobic threshold was found to occur at the work rate above which left ventricular function decreased during exercise in these patients. The time constant of VO2 during and following recovery from 6 minutes of 50 watts of constant work rate exercise was significantly longer (the kinetics of VO2 were slower) in patients with cardiovascular disease than in normal subjects. The time constant of VO2 was significantly negatively correlated with peak VO2 and maximum work rate obtained during the incremental exercise.(ABSTRACT TRUNCATED AT 250 WORDS)