SPARE HEARTS / Bridges for the heart / Assist pumps give diseased
organ rest, and chance to recover
Publication date: 10/13/1997 Page: 1 Section: AEdition: 3 STAR
Byline: RUTH SoRELLE
THE PATIENT was dead, despite the best efforts of Dr. Johannes Muller of the Berlin Heart Institute.

But when Muller turned off the Novacor heart-assist pump that he had used to supplement the man's
failing heart, he was shocked.
Even though the patient's brain wave was flat, the natural heart, nearly moribund a few months
earlier, was beating. It had recovered much of its function while on the artificial pump.
That experience less than five years ago prompted Muller and his colleagues to take a new path giving diseasedhearts a rest by letting artificial assist devices take over their job for a few months.
It's called the "bridge to recovery" and is one of many uses for heart-assist pumps that take over for
one of the heart's two pumping chambers called ventricles.
Of varying size and design, these small "half hearts" are major competitors to the larger total artificial
hearts that replace both ventricles.
Four heart assist devices are now in common use. Many more are on the drawing tables - smaller,
more efficient and requiring less energy.
For some patients, ventricular assist devices are lifesavers until a donor heart can be found. Then
they are a "bridge to transplant."
For some, they will become permanent implants, keeping the blood flowing when an ailing heart
cannot.
Most recently, they have taken on the "bridge to recovery" role.
Truck driver Albert Williams, 45, became a case study for the bridge to recovery while waiting for a
transplant. On May 3, 1995, his surgeon, Dr. O. Howard Frazier of the Texas Heart Institute in
Houston, implanted an assist pump called the HeartMate to tide Williams over while he waited for a
donor heart.
But none could be found. His 6-foot-4-inch frame and African-American ethnic background worked
against him because there were few similar heart donors.

 Donated hearts must be matched carefully so that certain biological markers are the same for the
donor and recipient, and some of these markers vary across racial lines.
Sixteen months after Williams got the HeartMate, a valve in it began to fail. He started feeling bad
again, and his wife insisted he return to the hospital.
At that point, Frazier opened Williams' chest and realized that his natural heart had improved, though
it hadn't fully recovered.
He decided to perform an experimental procedure called ventricular remodeling. Developed by Dr.
Randas Batista in Brazil, it involves taking a pie-shaped piece out of the left ventricle and sewing the
heart together again with a smaller diameter.
After a year with his remodeled heart, Williams is doing fine.
He chafes at insurance restrictions that keep him from working, but he will not consider a heart
transplant now unless his own heart begins to fail again.
"I'd rather have my own heart," he said.
He was not worried while he was on the pump. But even though it was implanted, wires ran from the
heart to an outside power source through openings in his skin that could become infected. And, he
said, "It's mechanical. Nothing mechanical is going to work forever."
The need to run power lines through the skin is a drawback to all four assist devices now in routine
use. The aim of most assist pump designers today is for five years of continuous pumping, with no
wires leading outside.
Ventricular-assist devices or VADs have one major advantage over total artificial hearts - they do not
require removal of the native heart.
No more than 20 percent of patients with heart failure need a total artificial heart, experts estimate.
"In point of fact, most people need only an assist," said Dr.
Leonard Golding, a heart surgeon who is working on an innovative assist pump at the Cleveland
Clinic. "They don't need their hearts cut out."
Of the four devices now in common use, only two, the pneumatic HeartMate and the Thoratec, are
approved for use in the United States. Both are powered by air and require bulky external units.

 The electrically driven Novacor and an electric version of the HeartMate are not approved for use in
this country yet, though both are used regularly in Europe and in this country under experimental
studies.
But the federal government is funding a $5.2 million study to determine how long-term implantation
of the electrically powered HeartMate compares to medical therapy as treatment for heart failure.
Doctors at Columbia Presbyterian Hospital in New York City, the Texas Heart Institute and the
Cleveland Clinic will conduct the research.
But even if the study proves the HeartMate better than medical therapy, it is far from ideal. It is large,
complicated and unwieldy for many patients.
There are better pumps on the drawing tables and in the laboratories - smaller, more easily
implanted and requiring less energy. But most are years away from human tests.
Part of the quest for the next generation of VADs is a debate over whether an assist pump must
mimic nature and deliver a pulsed flow or whether blood flow can be continuous.
In the human heart, blood comes into the atria and is pushed out of the ventricles in sequence.
When people measure their pulses, they are actually measuring the number of times that blood is
pushed or squeezed out of the heart.
But making a pulsatile heart assist pump is complicated.
It must have valves that open to let blood out and close to make sure it does not rush back in. It must
have a method of squeezing the blood out of the pumping chamber into the body or the pulmonary
arteries.
As the ventricle is squeezed, the completely implanted pump must have a compliance chamber that
accepts the air that is pushed out of the heart.
All of this results in a bulky device that is too big to go into the abdomen or chest of smaller patients.
The four pumps in use now are pulsatile. Most experimental continuous flow pumps fall into one of
two categories - rotary axial or rotary centrifugal.
The rotary approach got a boost in 1988 when Dr. Richard Wampler devised the HemoPump.
The eraser-sized assist pump spun at 25,000 revolutions per minute inside the ventricle to maintain
a steady flow of blood throughout the patient's body. The first patient to receive the pump was in
Houston for treatment at the Texas Heart Institute.

 No surgery was needed to implant a HemoPump. Instead, it was attached to a small catheter that
was inserted into a blood vessel in the patient's groin and threaded up through the maze of blood
vessels until it reached the heart's left ventricle.
With an external source providing power, the HemoPump began to suck blood out of an engorged
ventricle as soon as it got there.
The Heart Institute's Frazier was skeptical at first about the HemoPump
"I thought it would tear up the blood," he said. But when he tried it in calves, the pump did not injure
the blood.
The HemoPump, however, depended on bearings to maintain its high speed. Those quickly wore
out.
But the HemoPump opened a new way of thinking, and drew a host of artificial heart pioneers who
were looking for better technology.
One was Dr. Michael DeBakey, who wanted a smaller, simpler assist device than those currently
available.
His work on an axial flow pump similar to the HemoPump began when he met Johnson Space
Center engineer David Saucier, who was then awaiting a heart transplant.
In an axial flow pump, the fluid flows parallel to the pump's axis, pushed along by a propeller or rotor.
The assistpump contains only one moving part, which cuts down on the potential for failure.

Saucier eventually got the transplant in the program at Methodist that DeBakey had pioneered.
The engineer was intrigued with the notion of a pump and worked on it many years until his death in
1996.
Saucier and his colleagues first worked on the project informally, then formalized a collaboration with
the National Aeronautics and Space Administration. Recently, the design was transferred to a
proprietary company.
The result is a tiny pump no bigger than two double-A batteries that pumps the blood at 10,000
revolutions per minute but requires only about 8 watts of power.
It is so tiny that it will fit easily in the chest of a small woman or child, yet it is powerful enough to
pump five liters of blood per minute. The patient's own heart remains in the body and can contribute
somewhat to the blood flow.
The pump's controller and one battery will also be implanted.

 Power can be transmitted across the skin from a second battery worn externally. This reduces the
potential for infection through openings in the skin.
DeBakey, Dr. John Baldwin and Dr. Yukihiko Nose have implanted the pump in calves, which have
then lived as long as two months.
While the pump probably will be used as a bridge to transplant at first, DeBakey thinks it can become
a permanent implant as well - benefiting people who are not transplant candidates or for whom
matching donor organs are especially rare.
The pre-human testing is almost complete, and DeBakey hopes that the device can be tried in
humans by early next year.
Dr. Robert Jarvik's new assist device, the Jarvik 2000, is in the same general class.
In the beginning, he developed it with Frazier at the Texas Heart Institute, using funds Frazier had
put aside from money he is paid to remove hearts from donors.
"We did it on a shoestring," said Frazier.
Now Jarvik works with a corporate partner called Transicoil Inc., and has a federal grant from a
program designed to encourage innovative designs in assist devices.
"We started with the LVAD (left ventricular assist device) because that's the greatest need, and I
think it's the simplest," Jarvik said.
Eventually, he said, his design could be modified to create a total artificial heart. His name is
associated with an earlier artificial heart, the Jarvik-7, which was implanted in several patients during
the 1980s. It is now used as a bridge to transplant.
He anticipates being able to test his LVAD in people next year.
The device is about the size of a C battery - 1 inch in diameter and 21/2 inches long - and will be
inserted into the left ventricle.
It is a booster pump, Jarvik said, increasing blood flow while the real heart maintains the pulsed flow
that many feel is necessary.
He solved the bearing problem that plagued Wampler's HemoPump by suspending the bearings in
the blood itself, which served as a lubricant.
"I think we are close to our long-term objective to make a forgettable heart. People will wear this
thing and go about their lives normally most of the time," Jarvik said.

 One version will be tested at the Texas Heart Institute as a bridge to transplant. A second will be
tested in Oxford, England, as a permanent implant to keep a heart going for the rest of a patient's
life.
A third axial flow pump is being developed by Dr. Ken Butler at Nimbus Corp. in California.
His is not as small as Jarvik's, but otherwise the differences between the three now being designed
are "minute design details," Butler said.
His device is being tested in calves at the University of Pittsburgh, with human trial expected within
two years.
Axial flow pumps are not without drawbacks. Because there are no valves, blood can flow backward
if the pump suddenly stops, causing a life-threatening emergency. In some instances, blood can
remain in the pump, raising the threat of clots or damage.
A competing design is the radial, or centrifugal, flow pump, one of which is being developed at the
Cleveland Clinic under the direction of heart surgeon Golding.
He compares his device to the typical basement sump pump.
"Fluid comes in and goes out at right angles," he said.
He opted for the radial or centrifugal flow pump because it does not have the bearings problem that
plagues the high-speed axial pump and because it is easier to keep blood from clotting inside the
pump.
"Our design is sort of quite different," said Golding. "It's an inside-out motor. Our stator is in the
middle."
With the stator (the fixed shaft upon which the rotor or impeller is suspended) in the middle, heat
generated by the pump is dissipated in the blood.
Radial flow pumps churn at only 2,800 revolutions per minute.
"That's not necessarily a deficit if the pump is designed correctly," Golding said. "It doesn't damage
the blood."
Nose's pump is similar. He is working with the design because he feels it is the most durable of the
current generation of pumps.
But if axial flow pumps can be designed with more durable bearings, he believes that design will be
the optimal one.

 Golding is not so sure. "In fact, on ideal theoretical grounds, we need something in between both of
them."
One of the most unusual designs is that of Dr. Robert Whalen of the Whalen Institute in Boston. His
pump uses a skeletal muscle for power, eliminating the need for an internal or external power
system.
"It's been known for some time that if you stimulate a skeletal muscle, it changes biochemically and
structurally to more resemble cardiac muscle," he said.
Some surgeons have actually wrapped the muscle around the heart to augment its squeezing
potential, but results of that have been disappointing. Whalen wants to wrap the muscle around his
pump.
His pump has a barrel shaped bladder inside a rigid housing.
The muscle is wrapped around a separate chamber that contains fluid. The fluid is squeezed from
that chamber and used to drive the blood pump.
An external power source will keep the pump going while the skeletal muscle is being transformed
with constant stimulation, he said.
"If it's successful, the payoff is enormous," said Whalen. "It has unique advantages."
Abiomed Inc., which is also developing one of two federally approved total artificial hearts, is working
with surgeons at Columbia Presbyterian Medical Center in New York City to develop a "heart
booster" under a separate federal contract.
It cups the outside of the heart and squeezes it to boost its pumping action.
The heart booster itself never contacts the blood. Once again, the power source and control
mechanism are totally implanted.
Surgeons expect the pump to be ready for human trials within five years.
Five years, however, would be too long for 22-year-old Edgar Perez-Robles, who lives only because
of the mechanical pump in his abdomen.
The student from San Juan, Puerto Rico, has the physique of an athlete, but his strength has been
sapped by disease and surgery.
He came to Houston last February for a new medication that might help the heart that started to fail
two years ago for reasons that are still not known.

 But his condition rapidly deteriorated, and Frazier implanted an electrical HeartMate on March 31 to
keep him alive.
He and his mother consented to the procedure, but Robles said, "I don't remember anything from a
week before the operation and a month after it."
He was sick for the first two months he had the machine, but by June was itching to leave the
confinement of the hospital.
He was able to move into a nearby apartment by late summer.
The soft pulse of the machine is slightly audible in a quiet room, but Robles said he has gotten used
to the sound.
Now the future is up to his heart. He may recover and live without the mechanical heart. Or he may
need a heart transplant.
But without the ventricular assist pump, none of it would have been possible.
Tuesday: Hearts and red tape
Rotary axial flow LVAD
The valve-less heart-assist pump is no bigger than a ``C''
battery. The turbine device pumps oxygenated blood throughout the body. The electrically powered
pump does not beat or pulse like a real heart. In this case, the pump fits into the left ventricle. Other
pumps are implanted in the chest or abdomen.

PROS: Smallest of the three; some models can be implanted within the ventricle ... Low energy
requirement ... High output of blood.

CONS: Bearings can wear out quickly unless properly lubricated or suspended ... High speed of
pump can destroy red blood cells unless impeller is carefully designed ... Must be manufactured to
strict tolerances for pump to be effective ... No long-term experience in humans.