Lung Hyperinflation and neurohormonal activation in chronic heart failure
M Lorenzo Hernandez, G Minana, R De La Espriella, J Montiel, A Gasull, G Nunez, A Mollar, E Santas, P Palau, C Gonzalez, J Sanchis, J NunezAbstract
Background
The renin-angiotensin-aldosterone system (RAAS) plays a critical role in heart failure (HF) pathophysiology. In chronic obstructive pulmonary disease (COPD), hyperinflation increases intrathoracic pressure, which may impair venous return and reduce cardiac output, thereby exacerbating neurohormonal activation.
Purpose
In this study, we aimed to examine the association between parameters of hyperinflation and established markers of RAAS activation in outpatients with chronic HF.
Methods
This prospective, single-center study included 144 ambulatory patients with stable HF. Proxies of RAAS activation included reduced urinary sodium (UNa+) and chloride (UCl-) levels, along with increased BUN/creatinine(Cr) ratio. Plethysmography was carried out to quantify hyperinflation. The inspiratory capacity (IC)/ total lung capacity (TLC) and RV (residual volume)/TLC ratios were used as indexes of static lung hyperinflation, with lower values for the first, and higher values for the second, indicating reduced inspiratory reserve and greater ventilatory constraint. Multivariable linear regression models were constructed to evaluate the independent associations between hyperinflation indices and RAAS activation proxies.
Results
The mean age was 72.8±9.7 years, 108 (75%) were men, 125 (86.8%) had NYHA class II, 71 (49.3%) had preserved ejection fraction. The mean of IC/TLC was 0.37±0.11. The mean of UNa+, UCl- and BUN/Cr ratio was 76±35 mmol/L, 67±39 mmol/L and 21±7, respectively. After multivariate adjustment lower IC/TLC and higher VR/TLC were related to lower UNa+ (p=0.006, Figure 1a; p=0.002, Figure 1b) and lower UCl- (p<0.001, Figure 1c; p=0.009, Figure 1d). Lower IC/TLC was borderline associated with higher BUN/Cr (p=0.006, Figure 1e) and higher VR/TLC was linearly associated with higher BUN/Cr ratio (p=0.002, Figure 1f).
Conclusion
In stable patients with HF, lung hyperinflation was associated with indirect markers of RAAS activation and impaired renal sodium excretion. These findings suggest that mechanical lung–renal interactions may play an underrecognized role in the neurohormonal profile of chronic HF.Figure 1For image description, please refer to the figure legend and surrounding text.