The Metaboreflex and the Peripheral Chemoreflex Interact for the Regulation of Ventilation in Patients with Chronic Heart Failure

Patients with chronic heart failure (CHF) tipically present exacerbated ventilation (VE) response to exercise. This phenomenon is associated with exercise intolerance and worse prognosis, and seems to be mediated, at least in part, by abnormalities in the neural control of VE, such as enhanced VE response to activation of muscle afferents sensitive to metabolites (i.e., enhanced metaboreflex), as well as enhanced VE response to inhalation of hypoxic air at rest (i.e., enhanced peripheral chemoreflex). However, the interaction between these reflexes remains unknown in CHF. Then, we sought to test the hypothesis that the activation of the metaboreflex could enhance the contribution of the peripheral chemoreflex for the regulation of VE in patients with CHF. Six men with CHF under optimal pharmacological treatment (New York Heart Association class II-III, mean ± SD age of 55 ± 6 years and left ventricular ejection fraction (Simpson) 33.7 ± 2.9%) were submitted to 4 steady-state cycling sessions at 60% of max...