Background: In heart failure (HF), changes in lung mechanics and gas diffusion are limiting factors to exercise. Their contribution to an increased exercise ventilation to CO 2 production (VE/VCO 2) slope is undefined. Methods: A total of 67 stable HF patients underwent cardiopulmonary exercise and pulmonary function tests, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV 1), maximal voluntary ventilation (MVV), total lung capacity (TLC) and alveolar diffusing capacity with its subcomponents (alveolar-capillary membrane conductance (D m) and capillary blood volume (V c)). Results: Patients showed a mild restrictive pattern (FEV 1=85±15% and FVC=75±13% of normal predicted) and a moderate D m reduction (32±12 ml min -1 mm Hg -1). Average peak VO 2 was 15.6±4.0 ml min -1 kg -1 and the VE/VCO 2 slope was 39.6±11.0. At simple Spearman correlation analysis, all variables, but V c, correlated with peak VO 2; only D m correlated with VE/VCO 2 slope. At partial Spearman correlation, all variables lost the peak VO 2 correlation, and D m still inversely correlated with VE/VCO 2 slope (r=-0.35; p=0.005). In patients with a high VE/VCO 2 slope (cutoff value 34), despite comparable lung volumes, D m was significantly more depressed (30±13 vs. 35±10 ml min -1 mm Hg -1; p2. D m impairment rather than lung volumes correlates with exercise ventilation efficiency. This finding further adds to the pathophysiological relevance of an abnormal gas exchange in HF patients.
- Alveolar-capillary gas diffusion
- Exercise ventilation
- Left ventricular dysfunction
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine