Analysis of twenty-four hour heart rate variability in patients with panicdisorder

Growing evidence suggests that alterations in autonomic function contribute to the pathophysiology of panic disorder (PD). This retrospective study em ployed 24-h heart rate variability (HRV) analysis of Holter records to comp are autonomic function in PD patients (n = 38) with healthy, age- and gende r-matched controls. Both time and frequency domain measures were calculated , and a circadian rhythm analysis was performed. The SDNN index, 5-min tota l power, very low frequency (VLF) and low frequency (LF) power were signifi cantly lower in panic patients relative to controls over the 24-h period. H ourly means were significantly lower during some of the waking hours as wel l as the latter part of the sleep cycle. In contrast, the mean RR interval, RMSSD and high frequency (HF) power were comparable in patients and contro ls. Results suggest that sympathetic activity is depressed in PD patients u nder usual life conditions, leading to a relative predominance of vagal ton e. Findings of low HRV in PD patients are consistent with the high rate of cardiovascular morbidity and mortality in this population, as well as with the emerging view of panic as a disorder involving reduced flexibility and adaptability across biological, affective and behavioral dimensions. (C) 20 01 Elsevier Science B.V. All rights reserved.