IEEE Spectrum July, 2011 - 28

geek life
weight loss surgerY As
sYstems engineering

plastic surgeon gary Horndeski's new
surgical techniques decrease appetite

28

NA * iEEE SpEctrum * july 2011

again," he says. "A girdle
won't work, because it
doesn't provide nearly the
same pressure as mesh."
In preparation for a
2010 paper on the subject,
Horndeski discovered
supporting animal and
human studies from the
1940s to 2007. He worked out
a block diagram that models
the human weight feedback
system as an operational
amplifier (an integrated
circuit that amplifies output)
and then quantified "how
food amplifies your weight
and how that information
is fed back into the brain."
Horndeski has a patent
pending on the concept and
is waiting for the hospital
where he operates, Angleton
Danbury Medical Center,
in Texas, to approve this
surgery for weight loss. "I
was able to connect the dots
between stomach pressure
and weight loss in large part
because of my backgrounds
in math and system theory,
which is unusual for a
plastic surgeon," he says.
-Susan Karlin
spectrum.ieee.org

Alix Minde/Getty iMAGes

G

As a medical student, he
would often build Heathkits
for fun, once prophetically
putting together a digital
scale. Two decades later, he
found himself looking at the
human stomach with the
eye of an engineer. It wasn't
the first time Horndeski
had adapted engineering
techniques to plastic surgery-
he had already applied some
from doing abdominal
civil engineering concepts to
reconstruction surgery
breast reduction procedures.
during a fellowship at M.D.
Horndeski's epiphany
Anderson Cancer Center,
about weight loss came
about because he had already in Houston, from 1988 to
1989. His patients with the
reengineered the standard
tummy tuck. The established plastic mesh seemed to have
no trouble keeping their
procedure involves suturing
weight down; also, the mesh
the left and right sides of
increased external pressure
abdominal fascia-an elastic
on the stomach. Was there
tissue that overlies the
a connection? Horndeski
muscles and weakens with
hypothesized that receptors
pregnancy and age-to each
within the stomach wall
other. Instead, Horndeski
respond to that pressure just
reinforces the fascia with
as those in a normal eater
synthetic mesh. It's a
tell the brain to stop eating
technique he'd picked up
when the stomach is full.
"The brain has a reference
level of what's considered
full and compares it to the
information sent by the
stomach receptors," says
Horndeski. Recipients of a
standard tummy tuck put
weight back on because
the abdominal wall is not
reinforced. Patients with the
mesh reinforcement feel too
full to eat for several days
after surgery. "Once they
lose intra-abdominal fat, the
pressure on the stomach
WEIGHT STATES: plastic surgeon Gary Horndeski has reengineered
eases and then they can eat
the tummy tuck. photo: elisA GonzAlez

ary Horndeski
was early into his
plastic surgery
practice in the 1990s when
he noticed that his tummy
tuck patients continued to
lose excess fat and maintain
their new weights without
trying. He says he might
have shrugged it off as a
coincidence if it weren't for
his engineering background.
Instead, he speculated that
a person's satiety could be
controlled by additional
intra-abdominal pressure.
Horndeski-an aspiring
electrical engineer before
detouring into medicine in
1972 to avoid the Vietnam
War draft-had studied
mechanics at Case Western
Reserve University, in
Cleveland, which was one of
the first universities in the
country with a biomedical
engineering department.
"I'm the product of that
marriage," he says.
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Table of Contents for the Digital Edition of IEEE Spectrum July, 2011
