Implantable Pumps Extend Lives of Patients Too Sick For
DALLAS -- Pumps implanted into the chest to maintain
circulation can significantly extend the lives of the sickest
patients in end-stage heart failure who are not candidates for
heart transplantation, according to the results of a clinical
trial led by Duke University Medical Center cardiologists.
The pumps, known as left ventricular assistant devices
(LVADs), are employed when the heart's left ventricle – the
chamber of the heart that pumps blood throughout the body – is
too weak to pump enough blood to nourish the body's tissues.
LVADs have been used as successful short-term "bridges to heart
transplant" and are increasingly being considered as a
long-term heart failure destination therapy, said the
In the current trial, the researchers found that patients
who received LVADs had an average survival time of 10.3 months,
compared to 3.1 months for those who did not receive the
device. In this group of end-stage heart failure patients, 78
percent died within six months and 90 percent within a
"The patients who received the devices not only had a
lengthened quantity of life, but they appeared to have an
improved quality of life," said Duke cardiologist Joseph
Rogers, M.D., who presented the results of the trial Nov. 14,
2005, at the annual scientific session of the American Heart
Association meeting in Dallas. "We had patients who were doing
the normal activities of life, such driving cars, fishing and
Patients who were on the LVADs scored significantly higher
on standard measures of quality of life than patients in the
control group, Rogers said.
"This is a remarkably ill group of patients," Rogers
continued. "When you look at the control group, which was
receiving the best care medicine has to offer, we can only keep
ten percent of them alive after one year. We need to focus on
this as a group of patients, since most are still in the prime
of life and can still be quite productive."
To be considered for the trial, patients had to be taking
powerful intravenous drugs in the hospital just to keep their
hearts pumping, and they were also too sick to be considered
for a heart transplants. Most were in intensive care units.
"Despite the shortcomings of the device, the results of this
trial speak to our ability to improve the functionality for a
very sick group of patients," Rogers said. The major
complications of LVADs, said the researchers, include stroke,
bleeding episodes and infections, especially at the site in the
side of the body where the pump is connected to an external
power source and computer.
"We already had a lot of data on the device when it was
being used as bridge to transplantation," he continued. "We
knew it could go for extended periods without problems, and
that was the most compelling argument to use for implanting the
device in patients who have no other options."
For the trial, researchers enrolled 55 patients from 2000 to
2003. Thirty-seven patients received the device and 18 did not.
Patients were on average of 59 years old and as a group their
hearts beat at only 14 percent of normal strength. The pump
tested in the trial was the Novacor device, which is produced
by WorldHeart, Oakland, Calif.
"While the survival time for those patients receiving LVADs
was more than three times longer, we even had two patients who
are both four years out from implantation," said Rogers.
"Furthermore, unlike some earlier studies, there were no
catastrophic mechanical failures."
According to Rogers, there are a number of challenges to be
addressed before the use of LVADs can be considered as a
widespread destination therapy.
The first challenge is selecting appropriate patients, which
is crucial, since the patients most likely to survive would be
those who are quite sick, but not too sick to be beyond help.
This fine line in determining which patients are optimal will
need to be defined by future clinical trials, he said. The
other challenges pertain to the limitations of LVAD
"Like most new technologies, we're limited by our power
supply," Rogers said, "We need to develop a battery that is not
only small enough and powerful enough to be safely implanted
into the human body, but one that could be recharged through
the skin without burning the skin. That way there would be no
external parts, which would greatly reduce the incidence of
Another technological challenge involves the pump itself,
Rogers said. The Novacor device is a pulsatile pump which
contains blood in a polyurethane sack. The blood is then
propelled out of the pump between two pusher plates. However,
because of its size, it cannot be used in children or
comfortably in small women. Rogers said that numerous pump
designs are being tested that are smaller and lighter.
Durability will also be an issue, he said, since replacing an
LVAD entails just as substantial and involved a surgical
procedure as the initial placement.
Duke is currently participating in a number of different
trials testing different device models and pumps designs.
The trial was supported by WorldHeart, and was conducted at
13 sites in the U.S. and Canada. Rogers has no financial
interest in WorldHeart.