Spectral analysis of heart rate and blood pressure variability in primary Sjögren's syndrome.

BACKGROUND Autonomic dysfunction has been described in primary Sjögren's syndrome (SS). OBJECTIVE To investigate the circulatory autonomic regulation in patients with primary SS by power spectral analysis of heart rate and blood pressure variability. METHODS Forty three (42 female) patients with primary SS, mean age 52 years (range 23-80), with a mean disease duration of eight years (range 1-30) and 30 (15 female) healthy controls, mean age 43 years (range 21-68) were studied. In each patient blood pressure, heart rate, and respiration were measured continuously during supine rest and orthostatic challenge (60 degrees head-up tilt). Power spectral analysis was performed to determine possible differences in short term sympathetic and parasympathetic autonomic regulation between patients and controls. Furthermore, spectral parameters were studied in relation to illness severity and disease duration of the patients with primary SS. RESULTS After controlling for differences in age, heart rate variability of the mid-frequency band and the variation coefficient of systolic blood pressure were significantly lower in patients with primary SS than in controls during supine rest. During 60 degrees tilt patients with primary SS showed a significantly higher mean heart rate, mean systolic blood pressure, and variation coefficient of diastolic blood pressure, and a significantly lower baroreflex index than controls. After controlling for age, no differences were found either in heart rate variability, blood pressure results, and baroreflex sensitivity during supine rest and tilt between the subgroups divided according to disease duration, Schirmer test results, or between the subgroups with different fatigue scores. No differences were found in spectral data between the groups with and without positive antinuclear antibody serology. CONCLUSION For the group no differences in sympathetic and parasympathetic cardiac control were seen between patients with primary SS and controls, as assessed by spectral techniques, although some cardiovascular differences were found, particularly during orthostatic challenge.