title: Heart rate time series: decreased chaos after intravenous lactate and increased non-linearity after isoproterenol in normal subjects.
abstract: In this study, we reanalyzed our previous heart rate time series data on the effects of intravenous sodium lactate (n=9) and intravenous isoproterenol (n=11) using non-linear techniques. Our prior findings of significantly higher baseline non-linear scores (NL: S(netGS)) and significantly lower largest Lyapunov exponents in supine posture in patients with panic disorder compared to control subjects prompted this study. We obtained the largest Lyapunov exponent (LLE), and a measure of non-linearity (NL: S(netGS)) of heart rate time series. LLE quantifies predictability and NL quantifies the deviation from linear processes. There was a significant increase in NL score, (S(netGS)) after isoproterenol infusions and a significant decrease in LLE (an increase in predictability indicating decreased chaos), after intravenous lactate in supine posture in normal control subjects. Increased NL scores in supine posture after intravenous isoproterenol may be due to a relative increase in cardiac sympathetic activity or a decrease in vagal activity at least in certain circumstances, and an overall decrease in LLE may indicate an impaired cardiac autonomic flexibility after intravenous sodium lactate, as LLE is diminished by autonomic blockade by atropine. Band analysis of LLE (LF/HF) (LF: 0.04-0.15 Hz and HF: 0.15-0.5 Hz) showed an increase of these ratios during either condition with a higher sympathovagal interaction after the drug administration. These findings may throw new light on the association of anxiety and significant cardiovascular events.
authors.affiliation: Department of Psychiatry, Wayne State University School of Medicine, Detroit, MI, USA. vikramyershr@yahoo.com
authors.forename: Vikram Kumar
authors.initials: VK
authors.lastname: Yeragani
authors.forename: Radhakrishna
authors.initials: R
authors.lastname: Rao
authors.forename: Anusha
authors.initials: A
authors.lastname: Jayaraman
authors.forename: Robert
authors.initials: R
authors.lastname: Pohl
authors.forename: Richard
authors.initials: R
authors.lastname: Balon
authors.forename: Debra
authors.initials: D
authors.lastname: Glitz
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000009:adverse effects*; D000328:Adult; D001008:Anxiety Disorders / Q000139:chemically induced* / Q000503:physiopathology*; D004334:Drug Administration Schedule; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D007275:Injections, Intravenous; D007545:Isoproterenol / Q000008:administration & dosage / Q000009:adverse effects*; D019344:Lactic Acid / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D017711:Nonlinear Dynamics; D012494:Sampling Studies; D016683:Supine Position; D013997:Time Factors
chemical_list: D000318:Adrenergic beta-Agonists; D019344:Lactic Acid; D007545:Isoproterenol