Europace Advance Access published online on February 3, 2006
Europace, doi:10.1093/europace/euj053
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1 Autonomic Physiology Laboratory, Research Institute, Fundacion Cardiovascular de Colombia, Bucaramanga, Santander, Colombia; Syncope Unit, Arrhythmia Service, McMaster University, Hamilton, Ontario, Canada
* To whom correspondence should be addressed. Aims To determine whether central serotoninergic system activity is impaired by orthostatic challenge in patients with neurocardiogenic syncope (NCS). Methods and results Thirty-five [mean age: 24 (SD): 6 years] patients with a clinical history of NCS and positive head-up tilt test and 35 age-matched healthy volunteers (CON = 25 ± 5 years) with negative response were studied. Overnight dexamethasone suppression test (DST) (1.5 mg given at 11 p.m.) was performed to assess the sensitivity of the hypothalamic-pituitary-adrenal axis by measuring next day cortisol (µg/dL) at 8 a.m. and 4 p.m. Cardiac autonomic function, cortisol, and prolactin (ng/dL) were also determined at baseline supine (BAS) and after 5, 10, and 15 min of orthostatic stress (OS) at 60°. No significant differences were observed in cortisol plasma levels after the DST: CON = 0.6 ± 0.6 µg/dL vs. NCS = 0.6 ± 0.5; P = 0.7. Cardiac autonomic function, cortisol, and prolactin responses were similar in both study groups (CON vs. NCS; P > 0.05) during BAS: cortisol = 8.6 ± 4 vs.8.7 ± 4 µg/dL and prolactin = 16.8 ± 9 vs. 16.8 ± 9 ng/dL; OS-5: cortisol = 8.7 ± 5 vs. 8.5 ± 4 µg/dL and prolactin = 16.9 ± 9 vs. 15.8 ± 9 ng/dL; OS-10: cortisol = 8.5 ± 5 vs. 8.1 ± 3 µg/dL; prolactin = 16.2 ± 9 vs. 15.8 ± 9 ng/dL, and OS-15: cortisol = 9.0 ± 5 vs. 8.4 ± 4 µg/dL; prolactin = 17.1 ± 9 vs. 15.5 ± 9 ng/dL. Conclusion Central serotoninergic response during orthostatic challenge was not impaired in patients with recurrent NCS. These findings suggest that the activation of the hypothalamic-pituitary-adrenal axis is not altered in patients with recurrent NCS.
Received May 2, 2005
Accepted November 18, 2005
Article
Central serotoninergic response to orthostatic challenge in patients with neurocardiogenic syncope
Juan Camilo Guzman 1,
Ronald Gerardo Garcia 2,
Rejane Dillenburg 3,
Federico Silva Sieger 2,
Patricio Lopez-Jaramillo 2,
and
Carlos A. Morillo 1 *
2 Autonomic Physiology Laboratory, Research Institute, Fundacion Cardiovascular de Colombia, Bucaramanga, Santander, Colombia
3 Department of Paediatrics, McMaster University, Hamilton, Ontario
Carlos A. Morillo, E-mail: morillo{at}hhsc.ca or morillc@mcmaster.ca
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