Original papers: Sympathetic activitySympathetic and cardiac baroreflex function in panic disorderLambert, Elisabeth Aa; Thompson, Janea; Schlaich, Markusa; Laude, Dominiqueb; Elghozi, Jean-Lucb; Esler, Murray Da; Lambert, Gavin WaAuthor Information aHuman Neurotransmitter Laboratory, Baker Heart Research Institute, PO Box 6492, St Kilda Road Central, Melbourne, Victoria 8008, Australia and bINSERM E 0107, Faculte de Medecine, 15 rue de l Ecole de Medecine, 75270, Paris Cedex 6, France. Sponsorship: This work has been supported by an NHMRC block institute grant to the Baker Heart Research Institute. M.S. is the recipient of a Research Fellowship of the Deutsche Forschungsgemeinschaft DFG. G.W.L. is supported by an NHMRC Career Development Award and by a grant from the Rotary Health Research Foundation. Correspondence and requests for reprints to Elisabeth A. Lambert, Human Neurotransmitter Laboratory, Baker Medical Research Institute, PO Box 6492, St Kilda Road Central, Melbourne, Vic 8008, Australia. Tel: 61 3 85321345; fax: 61 3 85321100; e-mail: email@example.com Received 27 June 2002 Revised 12 August 2002 Accepted 21 August 2002 See editorial commentary page 2347 Journal of Hypertension: December 2002 - Volume 20 - Issue 12 - p 2445-2451 Buy Abstract Background Recent reports have demonstrated increased cardiac risk, and an association with essential hypertension in patients with panic disorder. The cause is not known, but possibly involves sympathetic nervous activation. In this study, we evaluated the arterial baroreflex control of vascular sympathetic nervous outflow and cardiac baroreflex function in panic disorder patients. Methods and Results We studied nine patients suffering from panic disorder and ten healthy subjects. Microneurographic recording of muscle sympathetic nerve activity (MSNA) was made with simultaneous recording of blood pressure (BP) and electrocardiogram (ECG). The relationship between MSNA and spontaneous diastolic BP (DBP) changes was assessed at rest and was defined as the arterial baroreflex control of MSNA. Cardiac baroreflex function was assessed using the sequence method. Anxiety was assessed using Spielberger's anxiety state and trait inventory. The slopes of the relationship between MSNA and DBP were more negative (steeper) in the panic disorder group compared with the control subjects (−5.97 ± 0.45 versus −3.06 ± 0.43 bursts/100 heart beats per mmHg, P < 0.001). Panic disorder patients had significantly higher state and trait anxiety scores. The slope of the relationship between MSNA and diastolic BP was significantly related to the trait anxiety of the subjects. There was no difference between the cardiac baroreflex sensitivity between the two groups. Conclusion Patients with panic disorder exhibit enhanced reflex gain of the arterial baroreflex control of MSNA but no change in the cardiac baroreflex. While any clinical significance this observation might have in relation to increased cardiac risk in panic disorder, or to concordance with essential hypertension, remains to be elucidated, increased reactivity of vasoconstricting sympathetic nerves may be a trait characteristic in this cohort. © 2002 Lippincott Williams & Wilkins, Inc.