Exaggerated beat-to-beat R amplitude variability in patients with panic disorder after intravenous isoproterenol.

Abstract

BACKGROUND:

Anxiety symptoms are associated with a marked increase in sudden cardiac death, suggesting an abnormality in cardiac autonomic function. Our previous studies show a relationship between R amplitude variability and sympathetic function.

METHODS:

We examined the effects of beta-adrenergic stimulation on R and T amplitude variability in panic disorder patients by infusing the beta-adrenergic agonist isoproterenol in 6 panic disorder patients and 11 normal subjects. The ECG signal was analyzed before the infusion and 5 min after the infusion was started. The outcome measures were the R and T detrended variance normalized for mean amplitudes (R(vm) and T(vm)) and the R(vi) and T(vi), measures which are normalized for the inter-beat interval variability in addition.

RESULTS:

Patients with panic disorder had significantly more variability in R and T amplitude than normal controls and the R amplitude variability was increased further by beta-adrenergic stimulation with isoproterenol, which was more pronounced in the patients.

CONCLUSIONS:

The isoproterenol-associated increase in R amplitude variability occurred in controls in the absence of significant anxiety. However, the increase in R amplitude variability was greater in patients with panic disorder, suggesting a greater sensitivity to beta-adrenergic effects of isoproterenol or to isoproterenol-induced anxiety.

• Authors: Vikram K Yeragani, Robert Pohl, Karl-Jürgen Bär, Pratap Chokka, Manuel Tancer
• Journal: Neuropsychobiology (Neuropsychobiology) Vol. 55 Issue 3-4 Pg. 213-8 ( 2007) ISSN: 1423-0224 [Electronic] Switzerland
• PMID: 17873495 (Publication Type: Clinical Trial, Journal Article)
• Copyright: (c) 2007 S. Karger AG, Basel.

Chemical References

• Adrenergic beta-Agonists
• Isoproterenol

Topics

• Adrenergic beta-Agonists (therapeutic use)
• Adult
• Analysis of Variance
• Electrocardiography
• Female
• Heart Conduction System (drug effects, physiopathology)
• Heart Rate (drug effects, physiology)
• Humans
• Injections, Intravenous (methods)
• Isoproterenol (therapeutic use)
• Male
• Panic Disorder (drug therapy, physiopathology)