Background: Impairment of lung mechanics, increase of pulmonary artery pressure and limitation of exercise capacity are common findings in chronic heart failure. The objective of the present study was to evaluate whether pulmonary mechanics are correlated with pulmonary hemodynamics, whether both are correlated with the functional capacity and whether the time course of their changes during exercise correlates with the exercise capacity.
Methods: We performed a cardiopulmonary exercise test (breath by breath analysis of ventilation and gas exchange, cycloergometer, 25 W increments every 3 min) with pulmonary hemodynamic monitoring in 38 heart failure patients. The parameters were analyzed at rest, 1 min after the work rate increase and at peak exercise.
Results: A significant linear correlation with peak oxygen consumption was found at rest for: mean pulmonary artery pressure (mPAP, r = -0.56), right atrial pressure (RAP, r = -0.42), pulmonary wedge pressure (PWP, r = -0.53), and total pulmonary (TPR, r = -0.53) and pulmonary vascular resistances (PVR, r = -0.45); after 1 min of exercise for: cardiac index (CI, r = 0.49), mPAP (r = -0.57), RAP (r = -0.60), PWP (r = -0.45), and TPR (r = -0.67) and PVR (r = -0.38); at peak exercise for: tidal volume (r = 0.63), CI (r = 0.63), RAP (r = -0.43), TPR (r = -0.65) and PVR (r = -0.43). A significant linear correlation with peak oxygen consumption was found, for the increment between rest and 1 min of exercise, for RAP (r = -0.58) and CI (r = 0.42) and, for the increments between rest and peak exercise, for tidal volume (r = 0.79) and CI (r = 0.61) and, for the ratio between the increment between rest and 1 min of exercise/increment between rest and peak exercise, for mPAP (r = -0.42), RAP (r = 0.51) and CI (r = -0.54). The same ratio of increment of mPAP (r = 0.39) and CI (r = 0.36) correlated with that of tidal volume.
Conclusions: This study provides evidence of a strong correlation between the respiratory function and pulmonary vascular pressure changes during exercise in heart failure.