The aim of this study is to investigate the effect of transauricular vagal nerve stimulation (taVNS) on cardiac autonomic functions in patients with spinal cord injury (SCI).
Aged between 18-60
Having a traumatic spinal cord injury
Cervical spinal cord injury patients with a history of autonomic dysreflexia
At least 6 months after the injury
Having a cardiac or neural pacemaker
Presence of pregnancy
Clinical coronary artery disease confirmed by invasive or coronary computed tomographic angiography
History of acute coronary syndrome (unstable angina, myocardial infarction)
Parallel
Active Transauricular Vagus Nerve Stimulation
DeviceActive taVNS application was performed by stimulating a sterile acupuncture needle (0.25x25 mm) placed on the left ear cymba choncae with a stimulator. Active taVNS group received for 10 days, 30 minutes with a current intensity of 1 mA, pulse width of 200 µs, frequency of 25 Hz and biphasic sinusoidal waveform. In the sham group, stimulation was applied to the lobulus auriculae of the left ear (which is not innervated by the vagus nerve) using the same current intensity and duration as the active group.
Sham Transauricular Vagus Nerve Stimulation
DeviceSham taVNS application was performed by stimulating a sterile acupuncture needle (0.25x25 mm) placed on the left lobulus auriculae of the left ear (which is not innervated by the vagus nerve) with a stimulator. Sham taVNS group received for 10 days, 30 minutes with a current intensity of 1 mA, pulse width of 200 µs, frequency of 25 Hz and biphasic sinusoidal waveform.
Low frequency/ High frequency (LF/HF)
Heart rate variability (HRV) is considered an indicator of neural control over the heart and is measured by analyzing the variations in NN intervals between consecutive R waves on an electrocardiogram (ECG).Frequency-domain analyses determine the power of fluctuations in heart rate signals within specific frequency bands. This analysis can be conducted using short-term Holter ECG recordings or data from 5-minute segments of a 24-hour Holter ECG. In our study, the short-term effects of taVNS on frequency domain HRV parameters will be evaluated using data obtained from 24-hour Holter ECG recordings on the pre-stimulation day (day 0) and day 11, and the acute effects will be assessed using data from 15-minute Holter recordings on day 1 and day 10.The LF/HF ratio is also one of the frequency-domain HRV parameters. LF/HF (ratio): low-to-high frequency power ratio The LF/HF ratio serves as an indicator of sympathovagal balance.
Total Power
Frequency-domain heart rate variability (HRV) parameters include Total Power, Ultra Low Frequency (ULF), Very Low Frequency (VLF), Low Frequency (LF), High Frequency (HF), and the Low Frequency/High Frequency (LF/HF) ratio. Total power, represents the total power of all frequency components within the frequency spectrum. It is the sum of the very low frequency (VLF), low frequency (LF), and high frequency (HF) components. Total power is an important parameter for the overall evaluation of autonomic nervous system functions. In our study, the short-term effects of taVNS on total power will be evaluated using data obtained from 24-hour Holter ECG recordings on the pre-stimulation day (day 0) and on day 11. Total power (millisecond²: ms²): Variance of all NN(Normal-to-Normal) intervals (\<0.4 Hz)
Ultra Low Frequency (ULF)
The ULF is also one of the frequency-domain HRV parameters. ULF represents the ultra low frequency. It indicates frequencies \<0.003 Hz. It does not directly reflect sympathetic or parasympathetic activity. In our study, the short-term effects of taVNS on ULF will be evaluated using data obtained from 24-hour Holter ECG recordings on the pre-stimulation day (day 0) and on day 11. ULF (ms²): ultra low frequency (\<0.003 Hz)
Very Low Frequency (VLF)
The VLF is also one of the frequency-domain HRV parameters. VLF represents the very low frequency. It indicates frequencies between \<0.003 and 0.04 Hz. It has been associated with baroreceptor activity, thermoregulation, the renin-angiotensin system, and endothelial functions. In our study, the short-term effects of taVNS on VLF will be evaluated using data obtained from 24-hour Holter ECG recordings on the pre-stimulation day (day 0) and on day 11. VLF (ms²): very low frequency (frequencies between \<0.003 and 0.04 Hz)
Low Frequency (LF)
The LF is also one of the frequency-domain HRV parameters. LF represents the low frequency. It indicates frequencies between 0.04 and 0.15 Hz. It reflects a combination of sympathetic and parasympathetic activity and is particularly associated with sympathetic activity in seated or standing positions. In our study, the short-term effects of taVNS on LF will be evaluated using data obtained from 24-hour Holter ECG recordings on the pre-stimulation day (day 0) and on day 11, while the acute effects will be assessed using data from 15-minute Holter recordings on day 1 and day 10. LF (ms2): low frequency power (0.04 to 0.15)
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