The effect of transcutaneous auricular vagus nerve stimulation and deep breathing exercises on heart rate variability in healthy participants and patients with rheumatoid arthritis and systemic lupus erythematosus

BackgroundRheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are chronic autoimmune diseases associated with a reduced function of the autonomic nervous system including an impaired function of the vagus nerve (VN). The VN has potential anti-inflammatory effects, which could be utilized in a new treatment approach using vagus nerve stimulation (VNS). Different types of VNS exist, but no direct comparison has been made of the methods in patients with RA and SLE.ObjectivesThe aim of this study was to compare the effect of transcutaneous auricular VNS (taVNS) and deep breathing (DB) on vagal tone in patients with RA or SLE and healthy participants and to investigate the washout effect assessed through time domain heart rate variability (HRV) measures (RMSSD (root-mean-square of successive differences), SDNN (standard deviation of N-N intervals), and PNN50 (percentage of adjacent N-N intervals that differ from each other by more than 50 milliseconds)).MethodsThe study was designed as an open label cross-over study. 42 healthy participants and 52 patients with RA or SLE performed two interventions, 30 minutes of taVNS and 30 minutes of DB. The interventions were separated by at least 24 hours. Before each intervention, two 5-minutes ECG-recordings were made to determine the participants’ baseline HRV. After each intervention three 5-minutes ECG-recordings were conducted in the following 30 minutes to investigate the potential washout effect.ResultsHealthy participants: A significant increase in SDNN, RMSSD, and PNN50 were found after DB. SDNN increased significantly immediately after taVNS. SDNN was significantly higher after DB compared to taVNS. Otherwise, there were no significant differences between the effects of the two interventions. Patients: A significant increase in SDNN, RMSSD, and PNN50 were present after both DB and taVNS. No significant differences were found between the effects of the two interventions. The effects of the interventions were still measurable 30 minutes after intervention, indicating no washout.ConclusionDB causes the greatest increase in HRV for healthy participants, while both DB and taVNS can equally elevate HRV in patients with RA and SLE, which support their use as a potential new treatment approach. However, their clinical effect needs to be investigated in future studies.AcknowledgementsThe authors thank patients and research personnel at Aalborg University Hospital.Disclosure of InterestsNone declared