TICKLING YOUR EAR COULD BE GOOD FOR YOUR HEART
Stimulating nerves in
your ear could improve the health of your heart, researchers have discovered. A
team at the University of Leeds used a standard TENS machine like those
designed to relieve labour pains to apply electrical pulses to the tragus, the
small raised flap at the front of the ear immediately in front of the ear canal.
The stimulation
changed the influence of the nervous system on the heart by reducing the
nervous signals that can drive failing hearts 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 is early days --
so far we have been testing this on healthy subjects -- but we think it does
have potential to improve the health of the heart and might even become part of
the treatment for heart failure."
The researchers
applied electrodes to the ears of 34 healthy people and switched on the TENS
(Transcutaneous electrical nerve stimulation) machines for 15-minute sessions.
They monitored the variability of subjects' heartbeats and the activity of the
part of the nervous system that drives the heart. Monitoring continued for 15
minutes after the TENS machine was switched off.
Lead researcher Dr
Jennifer Clancy, of 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 is
continually interacting with its environment -- getting 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 was in suppressing the sympathetic 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% 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 activity -- beta-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."
The researchers
found significant residual effects, with neither heart rate variability or
sympathetic nerve activity returning to the baseline 15 minutes after the TENS
machine had been switched off.
The technique works
by stimulating a major nerve called the vagus, which has an important role in
regulating vital organs such as the heart. There is a sensory branch of the
vagus in the outer ear and, by sending electrical current down the nerves and
into the brain, researchers were able to influence outflows from 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 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."
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