Dynamic cerebral autoregulation is impaired during submaximal isometric handgrip in patients with heart failure

Abstract

The incidence of neurological complications, including stroke and cognitive dysfunction, is elevated in patients with heart failure (HF) with reduced ejection fraction. We hypothesized that the cerebrovascular response to isometric handgrip (iHG) is altered in patients with HF. 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 min, corresponding to 1 min of baseline and 3 min of iHG exercise, at 30% maximum voluntary contraction, followed by 2 min of recovery. The resistance-area product was calculated from the instantaneous BP-CBV relationship. Dynamic cerebral autoregulation (dCA) was assessed with the time-varying autoregulation index estimated from the CBV step response derived by an autoregressive moving-average time-domain model. Forty patients with HF and 23 BP-matched healthy volunteers were studied. Median left ventricular ejection fraction was 38.5% (interquartile range: 0.075%) in the HF group. Compared with control subjects, patients with HF exhibited lower time-varying autoregulation index during iHG, indicating impaired dCA ( P < 0.025). During iHG, there were steep rises in CBV, BP, and heart rate in control subjects but with different temporal patterns in HF, which, together with the temporal evolution of resistance-area product, confirmed the disturbance in dCA in HF. Patients with HF were more likely to have impaired dCA during iHG compared with age-matched control subjects. Our results also suggest an impairment of myogenic, neurogenic, and metabolic control mechanisms in HF. The relationship between impaired dCA and neurological complications in patients with HF during exercise deserves further investigation. NEW & NOTEWORTHY Our findings provide the first direct evidence that cerebral blood flow regulatory mechanisms can be affected in patients with heart failure during isometric handgrip exercise. As a consequence, eventual blood pressure modulations are buffered less efficiently and metabolic demands may not be met during common daily activities. These deficits in cerebral autoregulation are compounded by limitations of the systemic response to isometric exercise, suggesting that patients with heart failure may be at greater risk for cerebral events during exercise.

Cerebrovascular Dynamics During Continuous Motor Task

“…The time course of and the amount of the evoked CBFV achieved by our setting corresponds to other motor tasks evoked flow studies targeting NVC insofar as flow is evoked bilaterally, remains elevated as long as the stimulus is present, and an attenuation does not ensue, a BP increase occurs comparably to those observed in NVC studies (Caldas et al 2018, Giller et al 2000, Llwyd et al 2017, Maggio et al 2013, Nikolic et al 2015. In contrast to these reports on NVC, however, our continuous motor task showed changes in the LF range (% /mmHg) and in the VLF range (phase) which are consistent with a disturbed dynamical CA (dCA, Zhang et al1998, Panerai et al 1999, Panerai et al 2001, Serrador et al 2005.…”

“…When CA fails an additional metabolic mechanism helps to keep oxygen concentration in the needed range by increasing the oxygen extraction rate as increasing the amount of the oxygen concentration released from hemoglobin (Leenders et al 1999). In pathological conditions such as acute stroke the coordinated overlapping of these mechanisms seems to be disturbed (Caldas et al 2018, Maggio et al 2013, Reinhard et al 2012, Rivera-Lara et al 2017) which might be relevant for an early start of rehabilitation (Coleman et al 2017, Li et al 2018, Chi et al 2018.…”

“…To characterize the system better its response to physiological stimuli like hand gripping, arm or leg movements, or visual tasks Vol. 68 (Caldas et al 2018, Giller et al 2000, Maggio et al 2013, Panerai et al 2012a) is analyzed. The duration of the used stimuli is usually short (e.g.…”

Cerebral Microcirculatory Blood Flow Dynamics During Rest and a Continuous Motor Task

“…Cerebral blood flow (CBF) is the combined result of BP, metabolic, and neuronal regulatory influences. In recent years, the influence of vaso-neural coupling (VNC) on CBF was determined to be a relevant contributor which can be disturbed even when cerebral autoregulation remains intact (Salinet et al, 2013, 2015; Caldas et al, 2018). To assess the dynamics of CA (dCA), applying a transfer function analysis (TFA) on the relationship between BP and CBFV is the most frequently used approach nowadays.…”

“…When applied over 5-min recording periods, the phase and gain results are reliable, and phase is more robust than gain for the grading of CA capabilities (Claassen et al, 2016; Sanders et al, 2018). Most VNC studies used short task periods (≤60 s) to investigate VNC (Chance et al, 1993; Obrig et al, 2000; Salinet et al, 2013, 2015; Caldas et al, 2018), and are, therefore, unsuitable for assessing TFA (Claassen et al, 2016). In addition to the TFA of the BP-CBFV macrocirculatory relationship, the TF analyses of the dynamics of the interaction between BP and [oxHb], as well as of [deoxHb] (microcirculatory response), have also shown that it is possible to grade CA failure (Reinhard et al, 2006; Cheng et al, 2012; Elting et al, 2018).…”