Heart failure patients healthier after ear stimulation (Wired UK)


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Heart failure patients could live healthier lives by having
nerves in their ears stimulated with a portable Tens machine.

Transcutaneous electrical nerve stimulation (Tens) machines are
commonly used to alleviate back pain and are even used during
labour. Now a team from the University of Leeds wants to adapt it
to tackle health problems that are impacted by changes in the
sympathetic nervous system, including heart disease and
hypertension. The technique works by altering the signals that can
make a heart beat too hard, by stimulating the vagus nerve.

It was already known that heart failure patients have increased activity of the
sympathetic nervous system, and that stimulating the vagus nerve
could help counter this. Different approaches have explored how
best to stimulate it. All of these, however, involve surgically
implanting electrodes into the region.

“This is invasive, expensive and associated with side effects,
therefore, we explored possible methods of stimulating the vagus
nerve non-invasively to make this therapy more widely available,”
Jennifer Clancy, of the University of Leeds’ School of Biomedical
Sciences, told Wired.co.uk. She and her team instead approached the
problem by exploring a small branch of the vagus that could be
reached at the tragus — located in the outer ear.

So far the technique has only been tested with 34 healthy
subjects who used the machine for 15-minute sessions. They noted,
however, that variability in heartbeat increased by about 20
percent — the sign of a healthy heart.

“Heart rate is constantly adapting to whatever you’re doing e.g.
heart rate speeds up when you breathe so that lots of oxygen from
the lungs can be absorbed in to the bloodstream and then heart rate
slows down when you breath out so you can conserve oxygen,” says
Clancy. “This variability is lost in conditions such as heart
failure and the heart becomes very poor at adapting to changes
making it difficult to walk up stairs etc. without getting
breathless.”

The team also noted that the technique helped to reduce nerve
activity by around 50 percent — a key change, considering heart
disease tends to increase activity of the sympathetic nervous
system. “This drives your heart to work hard, constricts your
arteries and causes damage,” explains Clancy. This kind of
increased activity would usually be controlled by using
beta-blockers in heart failure patients.

Following up in a small pilot study, however, the team found a
“significant improvement in heart rate variability” in patients
already using beta-blockers, when a small electrode was used to
stimulate the vagus. “This indicates that Tens stimulation could
have an added beneficial effect in these patients,”says Clancy.

“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.”

It’s the first time a Tens machine has been used in this way to
modify nerve control of the cardiovascular system, and the team
found the welcome effects lasted for 15 minutes after stimulation
occurred.

They are now in the process of launching a pre-clinical trial
for heart failure patients. “Once we have established that it also
works in patients we will investigate the long term effects of this
stimulation on the heart and quality of life,” says Clancy.

Overactive sympathetic nerve activity does not only impact heart
failure patients. It is associated with hypertension, depression
and obstructive sleep apnoea. “These conditions are currently quite
difficult to treat in some patients therefore this could be a
simple, inexpensive adjunctive therapy to improve outcomes.”

If it works, Clancy envisions an easy-to-use, portable
alternative to drugs for these conditions.

“We need to carry out further trials to establish how long this
residual effect lasts but, potentially, this could be something you
do for half an hour in the morning while you get ready and have
your breakfast.”

Details on the trial can be found in the
journalĀ Brain
Stimulation
.

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21 August 2014 | 11:38 am – Source: wired.co.uk

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