[Evaluation of the respiratory system in patients with heart failure based on spiro-ergometric exercise test...

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).

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.

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.

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.