Alveolar Membrane Conductance Decreases as BNP Increases During Exercise in Heart Failure. Rationale for BNP in the Evaluation of Dyspnea

Background: In left ventricular failure (LVF) patients, brain natriuretic peptide (BNP), lung diffusion for carbon monoxide (DLCO), and alveolar-membrane conductance (DM) correlate with LVF severity and prognosis. The reduction of DLCO and DM during exercise reflects pulmonary edema formation. Methods and Results: To evaluate, in LVF patients, the correlation between BNP and lung diffusion parameters at rest and during exercise, we studied 17 severe LVF patients, 13 moderate, and 10 normals measuring BNP and lung diffusion parameters before, at the end, and 1 hour after a 10-minute high-intensity constant-workload exercise. At rest, a significant correlation exists between BNP and lung diffusion parameters. Resting BNP, DLCO, and DM correlate with peak oxygen consumption (P <.0001 for all analyses). With exercise, BNP increase is significant (severe LVF 180 ± 49 pg/mL, moderate 68 ± 58, normals 18 ± 12); differently, only in severe LVF, with exercise, DLCO (-1.1 ± 0.7 mL/mm Hg/min, P <.0001) and DM (-6.4 ± 2.8, P <.0006) decrease. One hour after exercise, only in severe LVF, BNP is still higher than at rest, while DLCO, DM, and DM/Vc are lower. Significant correlations are observed between BNP and DM changes during exercise and recovery (P <.0001) in severe LVF. Conclusions: In severe LVF, BNP changes during exercise correlate with simultaneous reductions in DM, suggesting that BNP increase and pulmonary edema formation could be related.