The objective of this study was to assess the ventilatory parameters of cardiopulmonary exercise test (CPX) in patients with moderate and severe heart failure (HF).
Material and methods: We investigated 110 patients (pts) (mean age 52.1 +/- 11.1 years) with chronic HF due to dilated cardiomyopathy (42 pts) or coronary artery disease (68 pts). Resting spiro-metry, CPX on a treadmill (modified Naughton protocol, 83 pts, or modified Bruce protocol, 26 pts) and echocardiography were performed. The following parameters were analyzed: left ventricle ejection fraction (EF), forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). Both FEV1 and FVC are expressed as a percentage of predicted normal values (FEV1-%N, FVC-%N), FEV1/FVC ratio, rest and peak parameters of CPX ratio of physiological dead space to tidal volume (VD/VTrest, VD/VTpeak), respiratory rate (RRrest, RRpeak), minute ventilation (VErest, VEpeak), tidal volume (VTrest, VTpeak), endtidal Pco2 (PETCO2rest, PETCO2peak), endtidal Po2 (PETO2rest, PETO2peak), ventilatory equivalent for carbon dioxide (VE/VCO2rest, VE/VCO2peak) and oxygen (VE/VO2rest' VE/VO2peak), exercise time (T), peak oxygen uptake VO2peak' VO2peak%N, heart rate reserve HRR, peak heart rate HRpeak%N. After the mean follow-up period of 28.5 +/- 12 months, the patients were divided into groups: Group I: n = 78 pts who survived without heart transplantation (HTX) and Group II: n = 32 pts; n = 20 pts who died while on the transplant list; n = 12 pts who underwent urgent HTX.
Results: The patients in the group II had lower EF, more reduced peak oxygen consumption and shorter duration of exercise. We found that FEV1, FVC, FEV1-%N, FVC-%N were more severely impaired in group II. The patients in group II also had lower PETCO2rest and higher PETO2rest. There were no differences in the FEV1/FVC ratio, VD/VTrest, RRrest, VTrest, VErest, VE/VCO2rest, VE/VO2rest between the groups. The value of VD/VTpeak, VE/VCO2peak, VE/VO2peak, PETCO2peak were significantly higher in group II when compared with group I, but the values of PETO2 were lower. Despite a shorter duration of CPX in group II there were no differences in HRpeak%N, HRR, RRpeak, VTpeak, or VEpeak, between the groups.
Conclusion: At rest the patients with more severe HF appear to have a more restrictive pulmonary pattern and impaired pulmonary gas exchange. During exercise, the patients with severe HF have an increased dead space in the lung; more impaired pulmonary gas exchange and increased ventilatory response at a given workload.