title: Effect of nortriptyline and paroxetine on measures of chaos of heart rate time series in patients with panic disorder.
abstract: Tricyclic antidepressants have notable cardiac side effects, and this issue has become important due to the recent reports of increased cardiovascular mortality in patients with depression and anxiety. Several previous studies indicate that serotonin reuptake inhibitors (SRIs) do not appear to have such adverse effects. Apart from the effects of these drugs on routine 12-lead ECG, the effects on beat-to-beat heart rate (HR) and QT interval time series provide more information on the side effects related to cardiac autonomic function. In this study, we evaluated the effects of two antidepressants, nortriptyline (n=13), a tricyclic, and paroxetine (n=16), an SRI inhibitor, on HR variability in patients with panic disorder, using a measure of chaos, the largest Lyapunov exponent (LLE) using pre- and posttreatment HR time series. Our results show that nortriptyline is associated with a decrease in LLE of high frequency (HF: 0.15-0.5 Hz) filtered series, which is most likely due to its anticholinergic effect, while paroxetine had no such effect. Paroxetine significantly decreased sympathovagal ratios as measured by a decrease in LLE of LF/HF. These results suggest that paroxetine appears to be safer in regards to cardiovascular effects compared to nortriptyline in this group of patients.
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
mesh_terms: D000328:Adult; D000929:Antidepressive Agents, Tricyclic / Q000009:adverse effects* / Q000627:therapeutic use; D001143:Arousal / Q000187:drug effects*; D001341:Autonomic Nervous System / Q000187:drug effects; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced / Q000175:diagnosis; D008297:Male; D017711:Nonlinear Dynamics; D009661:Nortriptyline / Q000009:adverse effects* / Q000627:therapeutic use; D016584:Panic Disorder / Q000175:diagnosis / Q000188:drug therapy* / Q000523:psychology; D017374:Paroxetine / Q000009:adverse effects* / Q000627:therapeutic use; D018570:Risk Assessment; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D012815:Signal Processing, Computer-Assisted
chemical_list: D000929:Antidepressive Agents, Tricyclic; D009661:Nortriptyline; D017374:Paroxetine; D017367:Selective Serotonin Reuptake Inhibitors