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| By Reynolds M.
Delgado III, MD, FACC |
Because of the
shortage in donor organs, only 2000 patients receive heart transplants each
year. Yet more than 100,000 patients need a transplant every year. However, we
are fortunate to live in a time when advances in technology can do amazing
things and allow physicians to save lives when previously no hope
existed.
When
medicines won't work and a donor can't be found, we can treat patients dying of
heart failure by implanting a heart assist device. These devices are like
artificial hearts in that they take over the pumping function of the heart.
However, most of these devices are large and bulky, and must be implanted
during an open heart surgery procedure, which is very stressful to these very
ill patients.
Recently, however, efforts in cardiac medicine have focused on
using smaller devices and performing complicated surgeries with minimally
invasive techniques, including catheterization techniques. Cardiac
catheterization is less risky than surgery, can be done without anesthesia, and
eliminates surgical incisions.
A new innovation, the small TandemHeart(tm) percutaneous left
ventricular assist device, can be implanted for temporary support in the
catheterization laboratory. The first such implant of the TandemHeart assist
device was performed in Texas at St. Luke's Episcopal Hospital/Texas Heart
Institute this year. There is now a relatively new specialty among
cardiologists; those, like myself, who specialize in treating patients with
heart failure. This new type of mechanical pump device can support the failing
heart even during a cardiac arrest. The device can supply all the blood flow
needs of the body, even after the heart has completely
stopped.
The
TandemHeart device was implanted in a two-hour procedure in a woman who had a
critical blockage in the left main artery, which is responsible for supplying
blood to most of the heart. Because of the severity of her heart failure, she
was too weak to withstand a standard bypass surgery operation. Without
treatment, such a blockage would lead to certain death. She was hospitalized in
critical condition, after her referring doctor had given her no hope of
survival.
The
TandemHeart was implanted in the catheterization laboratory. The procedure
required inserting tubes through an artery and vein in the leg and passing the
tubes through the body to the heart. The pump itself sits just outside the
body, pumping blood back to the aorta, which is the largest artery in the body.
After the heart was fully supported by the assist device, a standard
angioplasty procedure was performed. During the angioplasty procedure, a stent
(a wire mesh tube) was inserted into the blocked artery to permanently "prop"
open the blockage. During stent deployment, the pump circulated blood
throughout the patient's body. Following the procedure, the pump was removed.
This procedure could not have been done without the support of the pump because
when the stent is deployed in the artery, it temporarily interrupts blood flow
completely. In the left main artery, this is usually immediately fatal. After
surgery, the heart immediately became stronger and recovered, and the patient
was discharged from the hospital in three days.
Our second case was similar. The
patient had severe coronary artery disease and a very weak heart, but this
patient needed bypass surgery. However, it was too risky to do bypass without
heart support; thus, the device was implanted before the surgical procedure.
This allowed us to avoid stopping the heart during surgery, which would have
been a risk to this patient. The surgery went well, and the patient's heart
function doubled, allowing us to quickly wean him from the
device.
These are
just two examples of how physicians can apply advances in technology in the
fight against heart disease, the number one killer of adults. Innovations in
computer-aided design and microminiaturization have led to a revolution in the
use of devices to treat heart disease. For example, the Jarvik 2000 is another
small assist pump, which is implanted in the operating room. Although no bigger
than a wine cork, the pump is essentially like a small jet engine that sits in
the heart and is able to pump all of the blood flow needs of the body. We have
implanted this device in two patients who have had the pump for three years and
who have returned to normal lifestyles.
The Texas Heart Institute has been at the forefront
of this field since the first assist pump was used successfully to bridge a
patient to heart transplant, a feat performed by Dr. Denton Cooley in 1978.
Since that time, Dr. O.H. Frazier has continued developing different pumps for
short- and long-term support of the heart, making the Texas Heart Institute a
world leader in this arena. Most recently, we have been working on developing a
totally implantable artificial heart that can permanently replace the heart.
Although we do not routinely replace the heart with a mechanical device, there
is no question that ongoing progress in technology will soon allow us to reach
this goal. Such an accomplishment would eliminate the need for donors and
ultimately allow people who otherwise would have died to live long, productive
lives with mechanical hearts.
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