title: Short-term complexity indexes of heart period and systolic arterial pressure variabilities provide complementary information.
abstract: It is unclear whether the complexity of the variability of the systolic arterial pressure (SAP) provides complementary information to that of the heart period (HP). The complexity of HP and SAP variabilities was assessed from short beat-to-beat recordings (i.e., 256 cardiac beats). The evaluation was made during a pharmacological protocol that induced vagal blockade with atropine or a sympathetic blockade (beta-adrenergic blockade with propranolol or central sympathetic blockade with clonidine) alone or in combination, during a graded head-up tilt, and in patients with Parkinson's disease (PD) without orthostatic hypotension undergoing orthostatic challenge. Complexity was quantified according to the mean square prediction error (MSPE) derived from univariate autoregressive (AR) and multivariate AR (MAR) models. We found that: 1) MSPE(MAR) did not provide additional information to that of MSPE(AR); 2) SAP variability was less complex than that of HP; 3) because HP complexity was reduced by either vagal blockade or vagal withdrawal induced by head-up tilt and was unaffected by beta-adrenergic blockade, HP was under vagal control; 4) because SAP complexity was increased by central sympathetic blockade and was unmodified by either vagal blockade or vagal withdrawal induced by head-up tilt, SAP was under sympathetic control; 5) SAP complexity was increased in patients with PD; and 6) during orthostatic challenge, the complexity of both HP and SAP variabilities in patients with PD remained high, thus indicating both vagal and sympathetic impairments. Complexity indexes derived from short HP and SAP beat-to-beat series provide complementary information and are helpful in detecting early autonomic dysfunction in patients with PD well before circulatory symptoms become noticeable.
authors.affiliation: Department of Biomedical Sciences for Health, Galeazzi Orthopedic Institute, University of Milan, Milan, Italy. alberto.porta@unimi.it
authors.forename: A
authors.initials: A
authors.lastname: Porta
authors.forename: P
authors.initials: P
authors.lastname: Castiglioni
authors.forename: M
authors.initials: M
authors.lastname: Di Rienzo
authors.forename: V
authors.initials: V
authors.lastname: Bari
authors.forename: T
authors.initials: T
authors.lastname: Bassani
authors.forename: A
authors.initials: A
authors.lastname: Marchi
authors.forename: A C M
authors.initials: AC
authors.lastname: Takahashi
authors.forename: E
authors.initials: E
authors.lastname: Tobaldini
authors.forename: N
authors.initials: N
authors.lastname: Montano
authors.forename: A M
authors.initials: AM
authors.lastname: Catai
authors.forename: F
authors.initials: F
authors.lastname: Barbic
authors.forename: R
authors.initials: R
authors.lastname: Furlan
authors.forename: A
authors.initials: A
authors.lastname: Cividjian
authors.forename: L
authors.initials: L
authors.lastname: Quintin
mesh_terms: D000328:Adult; D000465:Algorithms; D062186:Arterial Pressure / Q000502:physiology*; D001341:Autonomic Nervous System / Q000502:physiology*; D001795:Blood Pressure Determination / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013599:Systole / Q000502:physiology*