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Título :	RESEARCH ARTICLE Integrative Cardiovascular Physiology and Pathophysiology
Autor :	Ribeiro, Juliana Caldas
Palabras clave :	Pathophysiology. Integrative Cardiovascular Physiology. Dynamic cerebral autoregulation. Heart failure.
Fecha de publicación :	abr-2018
Descripción :	autoregulation is impaired during submaximal isometric handgrip in patients with heart failure. Am J Physiol Heart Circ Physiol 315: H254–H261, 2018. First published April 13, 2018; doi:10.1152/ ajpheart.00727.2017.—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 timevarying 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.
URI :	http://www7.bahiana.edu.br//jspui/handle/bahiana/2495
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