Cardiac Catheterization and
Coronary Angioplasty
Cardiac catheterization is a
diagnostic procedure that is used to visualize
the heart's chambers, valves, great vessels, and
coronary arteries. When a person has signs of
heart disease, this procedure can help the
doctor identify the precise problem. Cardiac
catheterization will reveal areas that have been
narrowed or blocked by atherosclerosis, the
fatty buildup of plaque.
Other terms used to describe
cardiac catheterization include: coronary
angiography, angiogram, cardiac cath and heart
cath.
During the procedure, a long,
narrow, flexible tube called a catheter is
inserted into the heart. The moving catheter can
be seen with X-ray equipment, providing the
doctor with a "road map" of the coronary
arteries and a picture of the heart's pumping
action.
Although cardiac catheterization
is a highly specialized diagnostic technique, it
is an extremely common procedure. Nearly a
million cardiac catheterizations are performed
each year in this country, often on an
outpatient basis. When done electively, the
complication rate is low.
Cardiac Catheterization
Laboratory: The procedure is performed by a
cardiologist in a cardiac catheterization
laboratory. Often referred to as the cath lab,
it is equipped with special instruments used for
cardiac procedures.
These include monitoring screens
(much like a television screen), X-ray
equipment, computers, and other instruments. The
patient is awake during the procedure and may
watch the test on the monitor. The X-ray camera
moves at various angles so the coronary arteries
can be seen from different perspectives.
Catheter Insertion:
Before inserting the catheter, the doctor will
administer a local anesthetic to numb the
insertion site. The catheter can be inserted
through an artery in the groin or an artery in
the arm. A special introducer sheath (a short
tube) will be inserted into the artery.
The catheter then will be
advanced to the point where the coronary
arteries branch off to the heart. The patient
will not feel the catheter as it moves through
the blood vessels.
Angiogram
and Ventriculogram: The catheter will be
moved through the arteries to the heart as the
doctor watches its progress with X-ray cameras,
which ensure accurate positioning of the
catheter within the aorta (the largest blood
vessel in the body) where the coronary arteries
originate. Once the catheter has reached its
destination, the doctor will flush X-ray dye
through the catheter to see the arteries (an
angiogram) and the major pumping chamber of the
heart (a ventriculogram).
The angiogram shows the doctor
an X-ray picture of the blood flow through the
coronary arteries. It reveals how many (if any)
blockages are present, where they are, and how
much blood flow is blocked in each artery. The
left ventriculogram, taken when dye is released
into the left ventricle, reveals the size of the
ventricle, pumping motion, possible leaks in the
heart's wall, or faulty heart valves.
Catheter Removal: If the
catheter was inserted through the femoral
artery, the sheaths used to access the artery
may be sutured in place for a few hours or
overnight. When the sheaths are removed, firm
pressure will be applied at the insertion site
with a device or manually for about 30 minutes,
or until the artery stops bleeding. A tight
pressure dressing then will be applied.
Test Results and Treatment:
Because the catheterization procedure provides
comprehensive, accurate information about the
heart, the doctor will be able to make a
well-informed decision about treatment.
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The test may prove that
symptoms are not related to the heart.
-
Medication may be altered
the dosage may be changed or perhaps stopped
altogether.
-
A new medication might be
indicated.
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Coronary angioplasty may be
recommended to widen the narrowing in the
coronary artery, improving blood flow to the
heart.
-
Surgery may be recommended
either coronary artery bypass surgery or
repair of the heart valves or walls.
Coronary Angioplasty
After reviewing the film and
X-ray pictures taken during the cardiac
catheterization, the doctor may recommend
coronary angioplasty, a nonsurgical technique.
The physician and patient will decide on the
proper timing and schedule the procedure
accordingly.
Coronary
angioplasty is also called percutaneous
transluminal coronary angioplasty (PTCA) or
balloon angioplasty. It is a specialized form of
cardiac catheterization. Insertion of the
catheter in the arm or groin and passage of the
catheter to the heart and coronary arteries is
technically similar to cardiac catheterization.
The Procedure: The
angioplasty procedure takes one to two hours
longer than cardiac catheterization. During the
procedure, several types of catheters are used
to widen the coronary arteries. Special markings
on the catheters are visible on X-rays, so the
doctor can ensure they are positioned correctly.
A guiding catheter is directed
over a wire to the opening of the diseased
coronary artery. This guiding catheter is a
large tube, so smaller tubes can be inserted
through it. The angioplasty catheter is a small,
thin piece of plastic tubing that has a balloon
at the tip. This is put through the guiding
catheter into the coronary artery while the
balloon is deflated. A guidewire also may be
used to move through narrow openings, and the
balloon will then be advanced over the wire.
Balloon catheters are made of special material
that expands to a specific size. A balloon
catheter that is about the same size as the
artery will be used.
Once the
balloon is positioned in the narrow portion
(called a lesion) of the artery, it is inflated
with X-ray dye so the
doctor can see it on the
monitor. The inflated balloon compresses the
plaque, pushing it against the wall of the
artery and slightly stretching the artery. The
balloon may be inflated for 60 to 90 seconds. It
may also be inflated and deflated several times
at each lesion to flatten the buildup. During
the time the balloon is inflated, blood flow is
temporarily blocked and the patient may
experience brief chest pain.
When the artery has been opened,
the balloon catheter and guidewires will be
removed. More contrast dye will be injected and
X-rays taken of the widened artery. The
increased blood flow through the artery will be
examined from several angles.
Depending on the type of blockage the patient
has, newer technologies such as stents,
atherectomy, radiation therapy or laser
procedures may be performed along with balloon
angioplasty to help prevent the vessel from
reclosing.
The Future
After successful coronary
angioplasty, many patients have no further
problems. Sometimes, however, the narrowing in
the coronary artery may return. This is called
restenosis and it most often occurs within the
first three to six months after a procedure.
Chest pain may be the first sign that restenosis
is developing. Restenosis usually can be treated
successfully with a second angioplasty. The
doctor also may recommend intravascular
radiotherapy (brachytherapy), which involves
using radiation in the artery to prevent further
blockages. Careful follow up in the period
following angioplasty is very important.
Several research programs are
underway to evaluate new treatments for coronary
artery disease. Patients should discuss these
possible options with their physician
