Dynamic cerebral autoregulation is impaired during sub-maximal isometric handgrip in patients with heart failure.

BACKGROUND: The incidence of neurological complications, including stroke and cognitive dysfunction is elevated in heart failure (HF) patients with reduced ejection fraction. We hypothesized that the cerebrovascular response to isometric handgrip (iHG) is altered in HF patients. METHODS: Adults with HF and healthy volunteers were included. Cerebral blood velocity (CBV, transcranial Doppler, middle cerebral artery) and arterial blood pressure (BP, Finometer) were continuously recorded supine for 6 minutes, corresponding to one min baseline, three min of iHG exercise, at 30% maximum voluntary contraction, followed by two min of recovery. Resistance-area product (RAP) was calculated from the instantaneous BP-CBV relationship. Dynamic cerebral autoregulation (dCA) was assessed with the time-varying autoregulation index (ARIt) estimated from the CBV step response derived by an autoregressive moving-average time-domain model. RESULTS: Forty HF patients and 23 BP-matched healthy volunteers were studied. Median [IQR] LVEF was 38.5 [0.075] % in HF group. Compared with controls, HF patients exhibited lower ARIt during iHG indicating impaired dCA (p<0.025). During iHG there were steep rises in CBV, BP, and heart rate in controls, but with different temporal patterns in HF which, together with the temporal evolution of RAP, confirmed the disturbance in dCA in HF. CONCLUSIONS: HF patients are more likely to have impaired dCA during iHG in comparison with age-matched controls. Our results also suggest an impairment of myogenic, neurogenic and metabolic control mechanisms in HF. The relationship between impaired dCA and neurological complications in HF patients during exercise deserves further investigation.