Exercise-induced changes in exhaled nitric oxide in heart failure

Background: In heart failure abnormalities of pulmonary function are frequently observed as shown by hyperpnea, reduced lung compliance, reduced alveolar-capillary gas diffusion, positive methacholine challenge and, during exercise, early expiratory flow limitation. Nitric oxide (NO) might be related to all the above abnormalities. Aims: We evaluated whether a correlation between exhaled NO (eNO) and lung function exists at rest and during exercise in heart failure. Methods: We studied 33 chronic heart failure patients and 11 healthy subjects with: (a) standard pulmonary function, (b) lung diffusion for carbon monoxide (DLCO) including its subcomponents, capillary volume and membrane resistance and eNO both at rest and during light exercise, (c) maximal cycloergometer cardiopulmonary exercise test. Results: Forced expiratory volume in 1 s (FEVI) was reduced in heart failure patients (83 +/- 17% of predicted), as was DLCO (75 +/- 18% of predicted) due to reduced membrane resistance (32.6 +/- 10.3 ml mmHg(-1) min(-1) vs. 39.9 +/- 6.9 in patients vs. controls, P < 0.02). Exhaled NO was lower in patients vs. controls (9.7 +/- 5.4 ppm vs. 14.4 +/- 6.4, P < 0.05) and was, during exercise, constant in patients and reduced in controls. No significant correlation was found between eNO and lung function. Vice-versa eNO changes during exercise were correlated with peak exercise oxygen consumption (r = 0.560, P < 0.001). Conclusions: The hypothesis of a link between eNO and lung function in heart failure was not proved. The correlation between eNO changes during exercise and peak VO2 might be due to hemoglobin oxygenation, which binds NO to hemoglobin. (C) 2003 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.