Aims: Alveolar gas diffusion (DLCO) is impaired in chronic heart failure (CHF). Diffusion depends on membrane diffusion (DM) and the amount of blood participating in gas exchange (VC). How DM, VC, and the alveolar-capillary unit behave in relationship to CHF severity is unknown. Methods and results: We measured pulmonary function, including DLCO, DM, VC, and alveolar volume (VA), in 191 CHF patients in NYHA class I-III. CHF patients were grouped accordingly to peak exercise oxygen uptake (pVO2): group 20 (n=27). DLCO, DM, VC, and VA were lowest in severe CHF and were linearly related to pV̇O 2 (DLCO, r=0.577, P20 (0.46±0.29), compared with 12-16 (0.34±0.19) and 16-20 (0.35±0.17). Conclusion: DLCO progressively worsens as CHF severity increases due to reduction in lung tissue participating to gas exchange (low VC and VA). In severe CHF, the few working alveolar-capillary units are the most efficient as shown by the high DM/VC. This is useful for maintaining gas exchange efficiency in severe CHF.
- Heart failure
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine