Heart rate and blood pressure changes during autonomic nervous system challenge in panic disorder patients

OBJECTIVE: To test the hypothesis that panic disorder (PD) patients have a heightened or deregulated autonomic nervous system at rest and during autonomic challenge compared with healthy controls (HC); and to test a second hypothesis that severity of illness differentiates patients; sympathovagal balance both at rest and during orthostatic challenge. METHODS: Spectral analysis of heart rate (HR) and blood pressure was performed on 30 PD and 10 HC participants during an orthostatic challenge (head-up tilt). RESULTS: PD patients presented higher HR (p <.001), lower heart rate variability (HRV) (p <.015), higher mean diastolic blood pressure (p <.006), higher low-frequency component of HR (p <.001), and a higher ratio of low-frequency to high-frequency component of HR (LF/HF) (p <.022) than HC at baseline. During tilt, PD patients responded with higher HR (p <.039), lower HRV (p <.043), increased mean diastolic blood pressure (p <.028), and a mild increase in LF/HF, whereas controls responded with a five-fold increase in LF/HF (p <.022). Patients with higher illness severity ratings (Clinical Global Impression Scale) showed higher HR (p <.002), lower HRV (p <.026), and a lower total power of systolic blood pressure (p <.02) compared with less ill patients. CONCLUSION: These findings demonstrate a consistently higher or deregulated autonomic arousal in PD patients at rest and during orthostatic challenge compared with HC. These data also reveal a possible association between the level of anxiety illness severity and sympathovagal balance, which may imply greater cardiac risk.