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Stimulating nerves in your ear could enhance the health of the heart, scientific study has discovered.
A team in the University of Leeds used a typical TENS machine like those designed to relieve labor pains to apply electrical pulses towards the tragus, the little raised flap in front of the ear immediately in front of the ears.
The stimulation changed the influence from the central nervous system around the heart by reducing the nervous signals that may drive failing hearts way too hard.
Professor Jim Deuchars, Professor of Systems Neuroscience in the University of Leeds’ Faculty of Biological Sciences, said: “You feel a bit of a tickling sensation in your ear when the TENS machine is on, but it is painless. It’s early days-so far we have been testing this on healthy subjects-but we believe it does have possibility to improve the health from the heart and can even end up part of the treatment for heart failure.”
The researchers applied electrodes to the ears of 34 healthy people and started up the TENS (Transcutaneous electrical nerve stimulation) machines for 15-minute sessions. They monitored the variability of subjects’ heartbeats and the activity of the area of the nervous system that drives the center. Monitoring continued for Fifteen minutes following the TENS machine was switched off.
Lead researcher Dr Jennifer Clancy, from the University of Leeds’ School of Biomedical Sciences, said: “The first positive effect we observed was increased variability in subjects’ heartbeats. A healthy heart does not beat like a metronome. It’s continually getting together with its environment-getting a little bit faster or a bit slower depending on the demands onto it. An unhealthy heart is more just like a machine constantly banging the same beat. We found that whenever you stimulate this nerve you receive about a 20% rise in heartbeat variability.”
The second positive effect was in suppressing the sympathetic central nervous system, which drives heart activity using adrenaline.
Dr Clancy said: “We measured the nerve activity directly and found that it reduced by about 50% whenever we stimulated the ear. This is important if you have heart disease or heart failure, you generally have increased sympathetic activity. This drives your heart to operate hard, constricts your arteries and causes damage. Lots of treating heart failure try to stop that sympathetic activity-beta-blockers, for instance, block the action of the hormones that implement these signals. Using the TENS, we saw a discount of the nervous activity itself.”
The researchers found significant residual effects, with neither heartbeat variability or sympathetic nerve activity going back to the baseline 15 minutes following the TENS machine had been turned off.
The technique works by stimulating a major nerve known as the vagus, that have an important role in regulating vital organs like the heart. There is a sensory branch of the vagus in the outer ear and, by sending electrical current down the nerves and in to the brain, researchers could influence outflows in the brain that regulate the heart. Vagal nerve stimulation has previously been used to treat conditions including epilepsy.
Professor Deuchars said: “We now need to understand how big and just how lasting the rest of the impact on the heart is and whether it will help patients with heart problems, probably alongside their usual treatments. The next stage is to conduct a pre-clinical study in heart failure patients.”
The research is published in the journal Brain Stimulation and was funded through the University of Leeds.
