Mechanical
pumps, which take over part of the work of a failing heart, are so effective
they will eliminate the need for heart transplants, leading heart
surgeons said.
Dr. Robert
Jarvik is pressing federal regulators to OK his newest device as an option
to transplants, while Dr. O. Howard "Bud" Frazier of St. Luke's Episcopal
Hospital/Texas Heart Institute told the American Heart Association meeting
Sunday the Jarvik 2000 is small enough and efficient enough to be used
in virtually all heart failure patients.
Frazier told
United Press International that Jarvik is knocking on doors in Washington
to get Food and Drug Administration approval for the use of the Jarvik
2000 as a permanent device.
Jarvik made
medical history 19 yers ago when a mechanical heart he invented was implanted
in Barney Clark, who subsequently died.
That bulky original
Jarvik heart never made it past the experimental stage.
So far, FDA
only allows use of the experimental pump as a "bridge to transplant," a
stipulation that eliminates patients who could benefit from it but who
do not meet strict guidelines for heart transplantation, Frazier said.
The same device
also is being studied in England, but there the pumps are used as curative
treatment for heart failure, he said.
Frazier, who
is assisting English investigators, said the 61-year-old Englishman who
received the first Jarvik 2000 early last year has recovered so completely
he recently was able to run down and apprehend a purse snatcher who attempted
to steal the power source for his device.
That power
is a small external battery he carried in "what looks like a small purse,"
Frazier said. Before the device was implanted, this man was so ill he could
not walk.
The Jarvik
2000 has been implanted in 18 patients in the United States and seven in
England. Frazier said there were two deaths following implant, "but both
were off-protocol patients," meaning they had other medical problems and
their deaths were not related to the pump implant. Both fatalities occurred
in the United States.
The Jarvik
2000 is typical of new generation pumps, said Dr. Timothy Gardner, professor
of cardiothoracic surgery, at the University of Pennsylvania, Philadelphia
and a spokesperson for the AHA.
Gardner told
UPI the new devices are not only much smaller than large, noisy predecessor
like the original Jarvik heart implanted 19 years ago, but they also are
continuous flow pumps rather than contractile, pulsating devices.
Typically,
with the new devices -- the Jarvik 2000 is the size of a C battery -- pump
is blood by the continuous spinning of a rotary device called an impeller.
There are about
a half-dozen of these devices now being studied, said Gardner. Some of
them do all the work of the heart and some, like Jarvik 2000, do some of
the work. When a continuous flow or non-pulsitile device takes over entirely,
the patient has no pulse.
Frazier said
in his experience patients do better with devices that allow a natural
pulse. The Jarvik 2000 does most "but not all the work of the heart. We
do allow a certain natural pulsitility to remain," Frazier said.
As more patients
are implanted with the device, he and other surgeons learned decreasing
the workload of the artificial pump decreased bleeding problems, a common
side-effect with some devices.
Frazier refused
to speculate about whether the FDA would give Jarvik permission to test
the Jarvik 2000 as a permanent implant.
But he and
other surgeons said FDA may become more willing to approve permanent implants
when results of a study that compares assist devices to drug therapy are
released.
That trial,
called REMATCH, randomized heart failure patients to either medical management
or an assist device.
Frazier said
the device used in that study is much larger than the Jarvik 2000, so it
"could not be implanted in women." Nonetheless, he said he expects the
results will find patients treated with drug therapy died while the assist
device saved lives.
Most heart
surgeons are expecting positive news from the REMATCH investigators, which
when combined with the lagging supply of donor hearts, makes the mechanical
devices even more appealing.
As Dr. Robert
Dowling of the University of Louisville/Jewish Hospital in Louisvillem,
Ky., explained, there are currently only about 2,500 human heart transplants
each year in the United States, but twice that many Americans are waiting
for hearts.
And that is
only the tip of the iceberg in terms of patients who have congestive heart
failure. He estimated as many as 20,000 Americans could benefit from mechanical
devices.
Dowling made
headlines last July when he lead a team that gave a dying patient the first
fully implantable artificial heart, called the AbioCor replacement heart.
That device uses continuous flow technology, but retains the patient's
natural pulse.
The AbioCor
is fully implantable because the power is transmitted through the skin
by placing a power disk over the area where the internal power supply is
implanted. The Jarvik 2000, on the other hand, is powered by an external
source attached to a thin wire that extends through the skin.
There are now
five patients who have received AbioCor hearts, Dowling told UPI. The most
recent implant occurred last Monday in Philadelphia at the University of
Pennsylvania. Dowling said that patient, a 51-year-old man, is doing well
but continues to experience breathing problems from fluid buildup in his
lungs.
The AbioCor
heart is used for patients in whom both the left and right ventricles have
failed, Gardner said.
Typically heart
failure first attacks the left ventricle, which becomes inefficient and
eventually leads to a large, flabby, poorly functioning heart. That causes
other organs, such as the kidneys, to fail because they receive too little
oxygen. Kidney failure causes fluid build-up, initially in the extremities
but eventually fluid accumulates in the lungs, making breathing very difficult.
Dowling said
this latest AbioCor patient may be experiencing lung problems because he
had fluid buildup prior to surgery. The other AbioCor patients are steadily
improving and Robert Tools, the first to receive the device, has left the
hospital for brief excursions around Louisville.
Dowling said
Tools is anxious to be discharged but will probably first be sent to an
in-patient rehabilitation unit before being sent home.
--
Copyright 2001 by United
Press International.
All rights reserved.
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