Autonomic imbalance, characterized by suppressed vagal activity and increased sympathetic activity significantly contribute to the development and progression of cardiovascular diseases. A non- invasive neuromodulation technique that may influence the cardiac autonomic nervous system (CANS) and restore autonomic imbalance is transcutaneous vagus nerve stimulation (tVNS). This thesis focuses on a novel cervical tVNS device (Pulsetto) which targets the vagus nerve through the neck. The aim of this research is to investigate the efficacy of this new device and provide insights into how cervical tVNS influences the CANS.

Two experiments were conducted: the first explored cervical tVNS in 8 atrial fibrillation (AF) patients, while the second involved 40 healthy participants, randomly assigned to either a stimulation group (n=30) or a sham group (n=10). Participants in the stimulation group received 10 minutes of stimulation. Heart rate variability (HRV) and cardiac conduction were measured via a 3-lead ECG, with data analysis focusing on HRV parameters, conduction intervals, and wave amplitude detection.

Significant HRV changes were observed during stimulation compared to pre-stimulation. Cervical tVNS significantly decreased mean HR (P<0.001) and LF/HF (P=0.038), while significantly increasing RMSSD (P=0.001), PNN50 (P=0.001) and HF power (P=0.003). Additionally, the QT interval and T-wave amplitude significantly increased (P=0.001 and P=0.030 respectively) in the stimulation group. None of these parameters changed in the sham group.

This thesis provides evidence that cervical tVNS can modulate cardiovascular autonomic control in healthy participants by increasing parasympathetic activity. Additionally, it is the first study to observe an increased T-wave amplitude during cervical tVNS, suggesting a novel effect on ventricular conduction. These insights indicate that cervical tVNS holds great potential for treating arrhythmias and other cardiovascular diseases.