CARDIOPULMONARY DETERMINANTS OF FUNCTIONAL-CAPACITY IN PATIENTS WITH CHRONIC HEART-FAILURE COMPARED WITH NORMALS

Background: Patients with chronic heart failure (CHF) are characterize d by abnormal gas exchange and ventilatory responses to exercise. Hypo thesis: This study compares variables obtained from cardiopulmonary ex ercise testing in 35 patients with CHF with 35 age- and weight-matched healthy subjects. A second goal was to obtain cardiopulmonary variabl es measured at ventilatory threshold to distinguish patient changes fr om those of healthy subjects. Methods: Exercise testing was carried ou t using bicycle ergometry with ramplike protocol (work rate increments 12.5 W/min). Gas exchange and ventilation were measured breath by bre ath. Results: Compared with healthy subjects, the VO2 in patients was lower at identical work rates (p<0.004) and at ventilatory threshold ( p<0.0001), and the slope of the VO2 curve during incremental exercise was natter (p<0.05). With the exception of heart rate, the variables f or VO2, VCO2, ventilation, O-2 pulse, ventilatory equivalents for O-2 and CO2, and V-D/V-T (physiologic dendspace to tidal volume ratio), as well as lactate differed significantly at identical work rates. With the exception of V-D/V-T, all cardiopulmonary variables showed signifi cant differences in their slopes during exercise. By means of a discri minant analysis, VCO2 and ventilation proved to be the most distinguis hing variables at ventilatory threshold be tween patients with CHF and healthy subjects. Conclusions: These results indicate the clinical us efulness of cardiopulmonary exercise testing when assessing functional impairment due to CHE For treatment evaluation, not only VO2 but also VCO2 and ventilation responses to exercise should be considered.