title: Impaired sympathetic regulation of cerebral blood flow in patients with cirrhosis of the liver.
abstract: Continuous recording of mean cerebral blood flow velocity (MCBFV) by Doppler ultrasound allows detection of low-frequency (LF) oscillations, which reflect sympathetic activity in the cerebral circulation. To establish whether the sympathetic drive to the cerebral circulation is altered in patients with compensated cirrhosis, and, if so, where alterations take place, LF oscillations of MCBFV, heart rate (RR interval) and systolic arterial pressure (SAP) were analysed in 10 patients with cirrhosis and 10 control subjects during supine rest and on stimulation of carotid baroreceptors using a neck chamber applying sinusoidal suction. Bivariate analysis was used to study the relationship between pairs of oscillations. In the case of a significant association, the delay in the appearance of the oscillation in MCBFV, SAP and RR was calculated. Baroreceptor stimulation induced significant increases in SAP LF and RR LF power in both groups, while MCBFV LF power increased only in controls. During baroreceptor stimulation, the lag phase between SAP LF and MCBFV LF power was significantly lower in cirrhotic patients than in control subjects (0.96 compared with 1.59 rad; P<0.01), indicating altered sympathetic regulation of the cerebral circulation. The baroreflex arc was intact, as indicated by the similar pattern of RR-SAP interval in patients and controls. Plasma noradrenaline levels increased significantly in both groups in response to head-up tilt. These results indicate that patients with cirrhosis have an altered sympathetic regulation of the cerebral circulation that is characterized by an inadequate response of resistance microvessels, despite adequate baroreceptor function.
authors.affiliation: Divisione di Medicina Interna I, Santa Maria Nuova Hospital, Firenze, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Lagi
authors.forename: Giacomo
authors.initials: G
authors.lastname: Laffi
authors.forename: Simone
authors.initials: S
authors.lastname: Cencetti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Barletta
authors.forename: Marco
authors.initials: M
authors.lastname: Foschi
authors.forename: Francesco
authors.initials: F
authors.lastname: Vizzutti
authors.forename: Renzo
authors.initials: R
authors.lastname: Bandinelli
authors.forename: Pietro
authors.initials: P
authors.lastname: Pantaleo
authors.forename: Cristina
authors.initials: C
authors.lastname: Tosti Guerra
authors.forename: Paolo
authors.initials: P
authors.lastname: Gentilini
authors.forename: Giorgio
authors.initials: G
authors.lastname: La Villa
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002560:Cerebrovascular Circulation; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D006975:Hypertension, Portal / Q000209:etiology / Q000503:physiopathology; D008103:Liver Cirrhosis / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D009638:Norepinephrine / Q000097:blood; D011187:Posture; D011311:Pressoreceptors / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D009638:Norepinephrine