20 LISTENER FEBRUARY 29 2020
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HEART DISEASE TREATMENT
A
uckland scientists developing a
new type of cardiac pacemaker
that mimics the heart’s natural
rhythm are hailing its potential
after animal studies in which it
restored muscle function and improved
the heart’s ability to pump. It is the first
time that a pacemaker has triggered elec-
trical signals as the body normally does, in
response to the inflation of the lungs. In
a healthy person, the heart rate increases
on inhalation and slows on exhalation,
but other pacemakers fire in a metro-
nomic rhythm, which lead investigator
Professor Julian Paton at the University
of Auckland, calls “unphysiological and
unnatural”.
He says the dramatic findings in rat
and sheep with heart failure showed that
after three days with the new pacemaker,
the amount of blood the animals’ hearts
could pump increased by 20-25%, an
unprecedented result for pacemakers, and
something that is usually only achieved
in a minority of patients with pacemakers
who are also taking optimal drug
treatment.
The technology uses a novel artificial
silicon neuron, which processes informa-
tion about the animals’ respiration and
commands the battery to release a voltage
pulse that paces the heart. “Your heart rate
is variable and completely synchronous
with your breathing cycle normally. This
brings back that variability and no one
has ever looked at whether or not that is
clinically beneficial in heart failure.”
An intriguing finding is that the
improvements in heart function kick
in three or four days after the device isswitched on in the animals, which, Paton
says, is a clue to the mechanism by which
it’s working. “It’s clearly not through
changes in the haemodynamics – the
movement of the blood – because that
would have happened more quickly. We
think potential gene expression is changing- that it is producing an epigenetic effect,
which means that the genome within the
heart cells is producing new proteins and
increasing the availability of calcium. And
that is really important for enabling the
heart muscle to contract more strongly.”
Paton and his colleagues, cardiovascu-
lar physiologist Rohit Ramchandra and
interventional cardiologist Nigel Lever,
are collaborating with scientists at the
universities of Bath and Bristol on the
work. Paton and Bath physics researcher
Alain Nogaret have co-founded a com-
pany, Ceryx Medical, to raise money to
take the technology to clinical trial withina few years.
Ramchandra says
the next preclinical trials will involve
exercise tolerance tests, and adding heart
medicines to see if they further improve
the condition of patients. “We have a
pacemaker now that we believe is going
to help heart-failure patients for the very
first time by potentially increasing their
heart-pumping capabilities. We are keen
to understand if this might also reduce
their sleep apnoea [a related condition
in which patients briefly stop breathing
during sleep]. You ask patients with heart
failure what they want back and they talk
about how they’d just love to be able to
get out of their seat, go to the kitchen and
put the kettle on without feeling breath-
less. We hope our pacemaker might help
them achieve this.”
The median age of heart-failure patients
is 78, but the number of people with
the condition is rising as the population
ages. Heart failure often occurs after heart
attacks, and about half those diagnosed
with it die within five years. “There’s no
fix for heart failure,” says Paton. But the
new device has the potential to change
that. “What we are seeing is the reversal of
some of this damage, which is remarkable
in itself. It’s very exciting – it’s getting me
out of bed in the mornings.”Ahead of
the pace
Research linking
heart rate and
breathing cycles is
set to revolutionise
pacemakers.
“We have a pacemaker
that is going to help
heart-failure patients byincreasing their heart-
pumping capabilities.”Julian Paton: reversing
the damage of heart
attacks.