Researchers have discovered that stimulating the nerves in your ears could improve heart health and reduce the risks of heart diseases. A team at the University of Leeds used a standard TENS machine to stimulate the ears to generate electrical pulses. The TENS machine is similar to those designed to relieve labor pains. These electrical pulses are applied to the tragus, which is the small raised, bud-like outgrowth at the front of the ears immediately before the ear canal. The stimulation caused by the
machine changed the effect of the nervous system that it has on the heart by reducing the nervous signals.
Jim Deuchars, professor of Systems Neuroscience in the University of Leeds and a Faculty member of Biological Sciences, says, You feel a bit of a tickling sensation in your ear when the TENS machine is on, but it is painless. It is early daysso far we have been testing this on healthy subjectsbut we think it does have potential to improve the health
of the heart and might even become part of the treatment for heart failure.
34 healthy subjects took part in this research and they had to apply electrodes to their ears and the TENS machine was switched on. The transcutaneous electrical nerve stimulation machines took 15-minute sessions and each subject was closely monitored. The key aspects to be monitored were the variability in the heartbeats of the subjects
and the activity responsible in the nervous system that drives the heart. Monitoring had to be continued for 15 minutes after the TENS machine was turned off.
Dr Jennifer Clancy, the lead researcher of the University of Leeds' School of Biomedical Sciences, says, The first positive effect we observed was increased variability in subjects' heartbeats. A healthy heart does not beat like a metronome. It is continually interacting with its environmentgetting a little bit faster or a bit slower depending on the demands on it. An unhealthy heart is more like a machine constantly banging out the same beat. We found that when you stimulate this nerve you get about a 20% increase in heart rate variability.
The second positive effect of stimulating the ears was in suppressing the sympathetic nervous system, which drives heart functioning using adrenaline.
We measured the nerve activity directly and found that it reduced by about 50% when we stimulated the ear. This is important because if you have heart disease or heart failure, you tend to have increased sympathetic activity. This drives your heart to work hard, constricts your arteries and causes damage. A lot of treatments for heart failure try to stop that sympathetic activitybeta-blockers, for instance, block the action of the hormones that implement these signals. Using the TENS, we saw a reduction of the nervous activity itself, said Clancy.
The researchers found that there were significant residual effects of this therapy even 15 minutes after the TENS machine was turned off. Neither the heart rate variability nor the sympathetic nerve activity came back to its normal state for about 15 minutes of the procedure completion.
This procedure works by stimulating a major nerve called the vagus, which plays an important role in regulating the heart and other vital organs. A sensory branch of the vagus found in the outer ear serves as the route to sending electrical down through the nerves and into the brain. Researchers could thus influence outflows from the brain that govern the heart.
Stimulation of vagal nerves has previously been used by doctors to treat conditions such as epilepsy.
We now need to understand how big and how lasting the residual effect on the heart is and whether this can help patients with heart problems, probably alongside their usual treatments. The next stage will be to conduct a pre-clinical study in heart failure patients, says Deuchars.
This research is published in the journal “Brain Stimulation” and was funded by the University of Leeds.