Oxygen uptake kinetics during low level exercise in patients with heart failure: relation to neurohormones, peak oxygen consumption, and clinical findings

Objective To investigate whether oxygen uptake (V˙o 2) kinetics during low intensity exercise are related to clinical signs, symptoms, and neurohumoral activation independently of peak oxygen consumption in chronic heart failure. Design Comparison ofV˙o 2 kinetics with peakV˙o 2, neurohormones, and clinical signs of chronic heart failure. Setting Tertiary care centre. Patients 48 patients with mild to moderate chronic heart failure. Interventions Treadmill exercise testing with “breath by breath” gas exchange monitoring. Measurement of atrial natriuretic factor (ANF), brain natriuretic peptide (BNP), and noradrenaline. Assessment of clinical findings by questionnaire. Main outcome measures O2 kinetics were defined as O2 deficit (time [rest to steady state] × ΔV˙o 2 − ∑V˙o 2 [rest to steady state]; normalised to body weight) and mean response time of oxygen consumption (MRT; O2 deficit/ΔV˙o 2). Results V˙o 2kinetics were weakly to moderately correlated to the peakV˙o 2 (O2 deficit,r = −0.37, p