Ambulatory monitoring of cerebrovascular responses to upright posture and walking in older adults with heart failure


Background Insufficient cardiac output (Q) in individuals with heart failure (HF) limits daily functioning and reduces quality of life. While lower cerebral perfusion, secondary to limitations in Q, has been observed during moderate-intensity efforts, individuals with HF may also be at risk for lower perfusion during even low-intensity ambulatory activities. Methods We determined whether HF is associated with an altered cerebrovascular response to low-intensity activities representative of typical challenges of daily living. In this study, we monitored central hemodynamics and middle cerebral blood velocity (MCAv) and cerebral tissue oxygenation (near-infrared spectroscopy) in 10 individuals with HF (78±4 years; left ventricular ejection fraction (LVEF) 20-61%) and 13 similar aged controls (79±8 years; LVEF 52-73%) during three randomized transitions: 1) supine-to-standing; 2) sitting-to-slow-paced over-ground walking; and 3) sitting-to-normal-paced over-ground walking. Results Throughout supine, sitting, standing, and both walking conditions, individuals with HF had lower cardiac index (Qi) and cerebral tissue oxygenation than controls (Ptextless0.05), and MCAv was lower across the range of blood pressure in HF (P=0.051) and during walking only (P=0.011). Individuals with HF had an attenuated increase in stroke volume index and Qi during normal-paced walking compared to controls (Ptextless0.01). Conclusion The indices of cerebral perfusion from MCAv and cerebral oxygenation were lower during ambulatory activities in individuals with HF; however, relationships between MCAv and blood pressure were not different between HF and controls indicating no difference in static cerebral autoregulation.

CJC Open