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. (c) 2007 S. Karger AG, Basel.
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 disorderpatients by infusing the beta-adrenergic agonist isoproterenol in 6 panic disorderpatients 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. (c) 2007 S. Karger AG, Basel.
Authors: Christopher J Mathias; David A Low; Valeria Iodice; Andrew P Owens; Mojca Kirbis; Rodney Grahame Journal: Nat Rev Neurol Date: 2011-12-06 Impact factor: 42.937
Authors: Phillip J Tully; Gary A Wittert; Deborah A Turnbull; John F Beltrame; John D Horowitz; Suzanne Cosh; Harald Baumeister Journal: Syst Rev Date: 2015-03-25