Does Transcutaneous Vagal Nerve Stimulation (tVNS) improve HRV?
This poster was presented at the 29th Annual U.S. Psychiatric & Mental Health Congress, held October 21-24, 2016, in San Antonio, Texas.
Background: Vagal nerve stimulation (VNS) is FDA cleared to treat epilepsy, depression, and obesity. Because VNS (tVNS) is a non-surgical form of VNS, targeting the auricular branch of the vagus nerve (ABVN) which conveys sensory information from a small area of skin of the external ear. tVNS may have autonomic effects, improving heart rate variability (HRV), which may make it an effective tool for treating anxiety and other conditions. Clancy et al. (2014) found that tVNS increased HRV; however, Napadow et al. (2012) did not. We seek to explore whether tVNS has autonomic effects in psychiatric outpatients by measuring HRV in patients receiving tVNS.
Methods: We used a transcutaneous electrical nerve stimulation (TENS) device with two ear electrodes placed on left concha and left ear lobe. Charts were reviewed for 21 patients (13 female, 8 male, mean age 44) who received tVNS (.4-.6 mA, 200 µs, 20 Hz) for 20 minutes. HRV was recorded 5 minutes before, 20 minutes during, and 5 minutes after treatment. Heart Rate Variability (SDNN) for each 5 minute interval was calculated.
Results: Participants experienced a significant increase in HRV only during the last 5 minutes of stimulation (P = 0.0197, n = 21).
Conclusion: Our data suggests that tVNS may have beneficial autonomic effects, which may contribute to symptom reduction in patients with anxiety and depression. Future studies may include longer stimulation time to measure any further changes in SDNN and increased current to see if the onset of HRV change has a shorter latency.