Suppression of cerebral hemodynamics is associated with reduced functional capacity in patients with heart failure

This investigation elucidated the underlying mechanisms of functional impairments in patients with heart failure (HF) by simultaneously comparing cardiaccerebral- muscle hemodynamic and ventilatory responses to exercise among HF patients with various functional capacities. One hundred one patients with HF [New York Heart Association HF functional class II (HF-II, n = 53) and functional class III (HF-III, n = 48) patients] and 71 normal subjects [older control (O-C, n = 39) and younger control (Y-C, n = 32) adults] performed an incremental exercise test using a bicycle ergometer. A recently developed noninvasive bioreactance device was adopted to measure cardiac hemodynamics, and near-infrared spectroscopy was employed to assess perfusions in the frontal cerebral lobe (Δ[THb] _FC) and vastus lateralis muscle (Δ [THb] _VL). The results demonstrated that the Y-C group had higher levels of cardiac output, Δ [THb] _FC, and Δ [THb] _VL during exercise than the O-C group. Moreover, these cardiac/peripheral hemodynamic responses to exercise in HF-III group were smaller than those in both HF-II and O-C groups. Although the change of cardiac output caused by exercise was normalized, the amounts of blood distributed to frontal cerebral lobe and vastus lateralis muscle in the HF-III group significantly declined during exercise. The HF-III patients had lower oxygen-uptake efficiency slopes (OUES) and greater V _E-VO ₂ slopes than the HF-II patients and age-matched controls. However, neither hemodynamic nor ventilatory response to exercise differed significantly between the HF-II and O-C groups. Cardiac output, Δ [THb] _FC, and Δ [THb] _VL during exercise were directly related to the OUES and VO _2peak and inversely related to the V _E-VCO ₂ slope. Moreover, cardiac output or Δ [THb] _FC was an effect modifier, which modulated the correlation status between Δ [THb]VL and V _E-VCO ₂ slope. We concluded that the suppression of cerebral/muscle hemodynamics during exercise is associated with ventilatory abnormality, which reduces functional capacity in patients with HF.