Heart Failure: Aggressive Technology
Brings Hope to Suffering Patients
January / February 2002
Today, new and existing technologies utilized in the field
of cardiac surgery bring hope to patients suffering from
end-stage
heart failure. Cardiac failure remains the leading cause
of death in the United States, affecting more than 5 million
people with greater than 700,000 deaths annually. The American
Heart Association estimates that the need for heart transplants,
which exceeds 6,000, far outweighs the availability of donors.
Because of this ever-increasing demand, scientists and physicians
are turning their efforts to mechanical devices that replace
some or all of the heart and its functions.
Mechanical Assist Devices
Symptoms of congestive heart failure include extreme shortness
of breath (possibly at rest or with simple activity), difficulty
sleeping in a flat position, fatigue, and swelling of the
ankles or abdomen. With heart failure, the heart does not
pump or squeeze effectively. People with heart failure may
benefit from pumps, mechanical assist devices or mechanical
hearts that take over the contractility or squeezing of the
heart.
In 1993, mechanical ventricular assist devices (Thoratec®
HeartMate®) were approved for use as a bridge to heart transplant
in the United States. They have been utilized very successfully
on a temporary basis, while patients await a heart transplant.
Patients, who may have died in the hospital waiting for a
donor, can remain in their own home supported by Thoratec®
HeartMate® or other assist devices.
The device is placed inside the body with one small driveline
that crosses the skin connected to batteries. Physicians
have
noticed a remarkable change in their patients while on the
device. "It is astonishing how much these patients improve.
They exercise, ride a bike, hike, play basketball-it is
a
phenomenal improvement in the quality of life," comments Mariell
L. Jessup, MD, director of the Penn's Heart Failure
and Transplantation Program at the University of Pennsylvania
Medical Center.
The success of Thoratec® HeartMate® has led to its consideration
as a permanent device. The recent REMATCH (Randomized Evaluation
of Mechanical Assistance for the Treatment of Congestive Heart
Failure) trial provided Thoratec® HeartMate® or standard medical
therapy at random to patients who were dying of end-stage
heart failure. This was the first comparison study of mechanical
devices. The results were recently published in the New England
Journal of Medicine and, although not perfect, the patients
with the device, statistically, lived significantly longer.
"Over the next year, our team plans to utilize similar devices
that enable poor functioning hearts to improve and possibly
avoid a transplant," says Michael
A. Acker, MD, surgical director of Penn's Heart Transplant
and Mechanical Assist Program at the University of Pennsylvania
Medical Center. These advances are particularly promising
for those over age 65, who are at higher risk for congestive
heart failure. Although this age group is not usually considered
for transplant, they may be considered for a mechanical
device.
Several new generation devices will soon be entering into
initial Phase I and II studies, offering more options for
permanent replacement. The Abiomed(tm) total heart is an artificial
heart that replaces the heart of a dying patient when transplant
is not an option. The hypothesis is that these patients will
live longer and have a better quality of life than patients
with standard medical therapy.
The Lion Heart is a new left ventricular assist device (LAVD)
located completely inside the body. Therefore, the patient
can be disconnected from the device's energy source for at
least part of the day, and infection rates (which are high
in the devices with a driveline that passes through the skin)
are expected to be very low.
One drawback is that the devices are fairly large, so small
women or children would not qualify as recipients. To combat
this problem, a new category of small mechanical devices is
being developed based on an entirely different concept of
pumping blood. The axial-flow pump is basically a high-speed
propeller that draws the blood out of the heart and propels
it in a "pulse-less" fashion to the body, up to 10 liters
a minute. The main advantage of these pumps is that they are
as big as your thumb. "Although there are concerns and tradeoffs
with having recipients living without a pulse, the pump is
being pursued because it is so small," explains Dr. Acker.
"This is a very exciting time in cardiac surgery. I see this
technology developing in the next five years to the point
where there will be mechanical replacements for one or both
ventricles. Initially, they will be used as a permanent device
for patients who are not heart transplant candidates, but
it is very likely that these devices will compete with transplant
itself," says Dr. Acker. "But we are not there yet."
More Advances with Mitral Valve Repair and Remodeling
Because of the persistent and worsening shortage of organ
donors, Penn Cardiac Care surgeons perform procedures
on patients
who years ago would not have been candidates for surgery.
Improvements in surgery have made mitral valve repair
surgery
(which have more effective results than a mitral valve replacement)
more common for patients who have severe mitral valve
leaks.
In addition, investigational techniques are being developed
to remodel hearts that have dilated and have abnormal cardiac
geometry. With the left ventriculoaneurysmorrhaphy, parts
of the heart that do not function are excluded from circulation
with dacron patches within the ventricle. This exciting theory
is based on the fact that large hearts do not function well
and, if the left ventricle can be restored to a more normal
size and shape, it will improve overall heart function.
Recently, new girdling devices have been evaluated to limit
or reverse ventricular remodeling. As the heart's function
worsens, it dilates, develops mitral valve leaks and grows
larger. Penn is the only hospital in the region currently
participating in a study examining the ACORN Cardiocor, a
fishnet polyester jacket that is sewn around the heart. If
this "jacket" can prevent the heart from dilating further,
it is anticipated that patients will live longer and feel
better. Patients are being randomized to receive the girdling
jacket or standard medical/surgical therapy. Patients with
either Class III heart failure, an enlarged heart, or those
with or without mitral insufficiency, are eligible.
Time of Hope
"This is an incredible time of hope for patients with heart
failure. Not only has our medical therapy improved dramatically
in the last five years, it seems that every six months there
is a new development with these new assist devices," adds
Dr. Jessup.
|
|
Referring Physicians: To speak with a Penn physician
or refer a patient, contact PennHealth through the secure online
referral form or by calling
1-800-789-PENN
(7366). |
 |
|
|
|
