Effects of Transcutaneous Electrical Stimulation on the Autonomous Nerve System in Healthy Young People

Summary

Cardiovascular disease is one of the most important causes of death and disability in the world. An autonomic imbalance is associated to cardiovascular risks and disorders. Electrical stimulation (ES) applied by surface electrodes is a non-invasive therapeutic approach with low side-effects. In the last years, some studies had investigated the effects of ES on the autonomic nervous system and cardiovascular system. However, different intensities, frequencies and electrode locations had been used, which makes difficult to clarify the optimal parameters.

The aim of this study is to analyze the effects of ES on autonomic nervous modulation in healthy subjects comparing three different locations of application for ES.

Participants will be aleatory assigned to one of three groups for a single-session of 20-minute transcutaneous ES: a) an auricular intermittent ES in an area that is believed to be connected to the vagal nerve (cymba conchae); b) an auricular sham intermittent ES, meaning a real ES but applied on an ear location not connected to the vagal nerve (scapha); and c) an upper back continuous ES (C7-T4), a placement that is thought to be connected to the stellate (sympathetic) ganglion. All the protocols will be stated at a non-painful intensity. After that, the hand grip exercise will be executed.

The heart rate variability (HRV) and heart frequency (HR) will be measured in four main times: the baseline, in the final minutes of the ES, after the ES and after finishing the hand grip exercise. Blood pressure will be measured also at all the time points except during the ES due to the possibility of interferences. Adverse effects will be assessed after ES and 48 h later. The study will provide initial knowledge about how different electrical stimulation locations contribute to reduce sympathetic excitation and improve the sympathovagal balance.

Conditions

• Healthy Volunteers
• Cardiovascular System
• Autonomic Nervous System

Interventions

DEVICE

Transcutaneous Vagus Nerve Stimulation (t-VNS)

Type of device and current: portable machine, low frequency current, constant current Type of wave: square biphasic pulses Pulse duration: 350 microseconds Frequency: 10 Hz Number of channels: one Location and electrodes: cymba conchae at right ear (vagus branch nerve area); a clip electrode will be applied with its cathode on anterior cymba conchae, the anode placed behind. Amplitude: from 2 times the perception threshold (individualized) at a comfortable, non-painful amplitude, and to a maximum of 9 mA. It will be increased, if necessary, each 5 minutes in order to maintain the same level of tingling sensation On-Off times: trains of 30 s on, 5 s rump up, 1 s rump down, 24 s off Duration: 20 minutes

DEVICE

Transcutaneous Sympathetic Ganglion Electrical Stimulation (t-SES)

Type of device and current: portable machine, low frequency current, constant current Type of wave: square biphasic pulses Pulse duration: 350 microseconds Frequency: 5 Hz Number of channels: two Location and electrodes: cervicothoracic area (stellate ganglion region); first channel: new 5 cm x 5 cm self-adhesive electrodes will be applied at 1-1.5 cm both sides of the vertebral spinous processes, approximately from C7 to T4, upper cathode on the left side of C7 and lower cathode on the right side. Amplitude: 2 mA above the muscle contraction threshold (individualized) at a comfortable, non-painful amplitude and to a maximum of 25 mA. It will be increased, if necessary, each 5 minutes in order to maintain the same level of muscle contraction On-Off times: no trains, continuously delivered Duration: 20 minutes

DEVICE

Sham Transcutaneous vagus nerve stimulation (Sham t-VNS)

Type of device and current: portable machine, low frequency current, constant current Type of wave: square biphasic pulses Pulse duration: 350 microseconds Frequency: 10 Hz Number of channels: one Location and electrodes: scapha at right ear (non vagus innervated region); a clip electrode will be applied with its cathode on anterior scapha, the anode placed behind. Amplitude: from 2 times above the perception threshold (individualized) at a comfortable, non-painful amplitude, and to a maximum of 9 mA. It will be increased, if necessary, each 5 minutes in order to maintain the same level of tingling sensation On-Off times: trains of 30 s on, 5 s rump up, 1 s rump down, 24 s off Duration: 20 minutes

Sponsors & Collaborators

• Universidade da Coruña

  lead OTHER

Principal Investigators

• Alicia Martínez-Rodríguez, PhD · Universidade da Coruña (UDC)

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2022-03-22

Primary Completion

2022-06-27

Completion

2022-06-29

Countries

• Spain

Study Locations