Background Patients with fibromyalgia syndrome (FMS) have autonomic nervous system (ANS) related disorder1. The orthostatic stimulus is an important method for the assessment of neurocardiac integrity2. However, little is known about the cardiac autonomic response to the active standing test in women with FMS.
Objectives To evaluate the cardiac autonomic control response to the active standing test in women with FMS.
Methods Ten women with FMS (FMSG n=10) and ten healthy women (HG n=10) took part in the study. The volunteers were submitted to the recording of RR intervals (RRi) during 15 min in supine and 15 min in orthostatic (active standing) positions. RRi were recorded by a heart rate monitor. The parameters of the frequency domain were determined by the heart rate variability (HRV) spectral analysis, obtained in low frequency (LF, 0.04–0.15 Hz) and high frequency bands (HF, 0.15–0.4 Hz) in normalized units (n.u.) and LF/HF ratio3.
Results The results are shown in table 1. There were significant group x posture interaction for LF (n.u.) and HF (n.u.). Post hoc analysis revealed that the HG increased LF (n.u.) and decreased the HF (n.u.) during active standing, compared to the supine position. On the other hand, the FMSG presented no significant differences between supine and orthostatic position. Regarding between group comparisons, FMSG presented higher LF (n.u.) and lower HF (n.u.) at supine position.
Conclusions FMSG showed cardiac autonomic dysfunction at supine position, characterized by higher sympathetic and lower parasympathetic cardiac autonomic modulation. In addition, FMSG present a blunted cardiac autonomic control response to the active standing, characterized by a lack of cardiac sympathetic modulation increase and parasympathetic decrease. Therefore, the neurocardiac integrity seems to be compromised in the FMSG.
Zamunér AR, Forti M, Andrade CP, Avila MA, Silva E. Respiratory Sinus Arrhythmia and its Association with Pain in Women with Fibromyalgia Syndrome. 2015 a.[Epub ahead of print].
Furlan R, Colombo S, Perego F, Atzeni F, Diana A, Barbic F, et al. Abnormalities of cardiovascular neural control and reduced orthostatic tolerance in patients with primary fibromyalgia. J Rheumatol. 2005;32:1787–1793.
Task Force. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Task force of the European society of cardiology and the North American Society of pacing and electrophysiology. Circulation. 1996;93:1043–1065.
Acknowledgement This study was supported São Paulo Research Foundation (FAPESP), grants #2011/22122–5, #2013/17504–1 and 2015/23449–9 and by the National Council for Scientific and Technological Development (CNPq), grants no. 483032/2012–3 and 307187/2013–6.
Disclosure of Interest None declared