title: Evaluation of the correlation between cardiac and sympathetic baroreflex sensitivity before orthostatic syncope.
abstract: The study investigates the two different aspects of the baroreflex control resulting in two baroreflex sensitivity (BRS) indexes: i) sympathetic BRS (sBRS); ii) cardiac BRS (cBRS). sBRS was assessed as the slope of the regression line of the conditional probability of detecting a burst on the integrated muscle nerve sympathetic activity (MSNA) given an assigned diastolic arterial pressure (DAP) on DAP. cBRS was estimated from spontaneous heart period (HP) and systolic arterial pressure (SAP) via a spectral approach in the low (0.04-0-15 Hz) and high (0.15-0.5 Hz) frequency bands respectively. Both sBRS and cBRS were assessed in eight healthy subjects undergoing three experimental sessions: supine resting position (REST), 80 degrees head-up tilt test (TILT) and before the occurrence of pre-syncope symptoms (TILT_PRE). Results showed a decrease of both sBRS and cBRS during TILT and a baroreflex impairment during TILT_PRE. sBRS and cBRS were linearly correlated during TILT but became uncorrelated during TILT_PRE. Findings suggest a failure of both "baroreflexes" and their disassociation during TILT_PRE.
authors.forename: Andrea
authors.initials: A
authors.lastname: Marchi
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bari
authors.forename: Beatrice
authors.initials: B
authors.lastname: De Maria
authors.forename: Sergio
authors.initials: S
authors.lastname: Cerutti
authors.forename: Karsten
authors.initials: K
authors.lastname: Heusser
authors.forename: Jens
authors.initials: J
authors.lastname: Tank
authors.forename: Jens
authors.initials: J
authors.lastname: Jordan
authors.forename: Franca
authors.initials: F
authors.lastname: Barbic
authors.forename: Raffaello
authors.initials: R
authors.lastname: Furlan
authors.forename: Alberto
authors.initials: A
authors.lastname: Porta
mesh_terms: D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D006801:Humans; D011187:Posture / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*; D013575:Syncope / Q000503:physiopathology*; D018667:Tilt-Table Test