Heart rate time series: decreased chaos after intravenous lactate and increased non-linearity after isoproterenol in normal subjects

• Published in: Psychiatry research Vol. 109; no. 1; pp. 81 - 92
• Main Authors: Yeragani, Vikram Kumar, Rao, Radhakrishna, Jayaraman, Anusha, Pohl, Robert, Balon, Richard, Glitz, Debra
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 31.01.2002; Elsevier
• Subjects: Adrenergic beta-Agonists - administration & dosage; Adrenergic beta-Agonists - adverse effects; Adult; Adult and adolescent clinical studies; Anxiety; Anxiety Disorders - chemically induced; Anxiety Disorders - physiopathology; Anxiety disorders. Neuroses; Biological and medical sciences; Chaos; Drug Administration Schedule; Female; Heart Rate - drug effects; Heart Rate - physiology; Heart rate variability; Humans; Injections, Intravenous; Isoproterenol - administration & dosage; Isoproterenol - adverse effects; Lactic Acid - administration & dosage; Lactic Acid - adverse effects; Largest Lyapunov exponent; Male; Medical sciences; Non-linear; Nonlinear Dynamics; Normal control subjects; Panic disorder; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Sampling Studies; Spectral analysis; Supine Position; Time Factors; Chaos; Normal control subjects; Non-linear; Anxiety; Largest Lyapunov exponent; Heart rate variability; Spectral analysis; Human; Agonist; Isoprenaline; Panic; Intravenous administration; Healthy subject; Pathophysiology; Bronchodilator; Anxiety disorder; Prediction; Time series; β-Adrenergic receptor agonist; Experimental study; β-Adrenergic receptor; Heart rate; Autonomic nervous system; Non linear model; Biological effect; Hemodynamics; Comparative study
• ISSN: 0165-1781; 1872-7123
• DOI: 10.1016/S0165-1781(01)00355-9

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.