How It Is Done
This test is performed in the cardiac
catheterization laboratory ("cath lab") by a
cardiologist. See a picture of a
cardiac catheterization lab
.
You will be asked to lie on a flat
table under a large X-ray machine. Several small metal leads (electrodes) will
be attached to your legs and arms with a special paste or gel. These leads are
connected to an
electrocardiogram (EKG, ECG) machine that continuously
records the electrical activity of your heart during the test.
A
device called a
pulse oximeter that measures oxygen levels in your
blood and monitors your pulse may be clipped to your finger.
An
intravenous (IV) needle will be inserted into a vein in one of your
arms to give you fluids or medicine during the procedure. You will receive a
medicine to help you relax (sedative) through the IV line. You may
be awake during the procedure. But even if you are awake, the sedative may make
you so sleepy that you may not remember much about the procedure.
The thin flexible tube (cardiac catheter) is usually inserted in your
groin (femoral artery). Other sites that may be used are the crease of your
elbow (brachial artery) or your wrist (radial artery). The catheter insertion
area will be shaved and cleansed with an antiseptic solution before the test.
Sterile towels will be draped over your arm or leg, except for the area over
the catheter insertion site.
A
local anesthetic will be injected into the skin at the
insertion site. A blood vessel is punctured by a special needle or exposed by
making a small incision in the skin so that the catheter can be passed into the
blood vessel. The catheter is slowly advanced through the blood vessel into
your body. The catheter tip is moved into various positions in the heart's
vessels and chambers while the doctor watches its progress on the imaging
screen. Pressures within the heart chambers can be measured. Blood and heart
tissue samples may also be removed through the catheter, if necessary.
See a picture of the
placement of a cardiac catheter
.
You may be asked to hold your breath
or move your head slightly to provide clear views of the heart and its blood
vessels.
A small amount of dye (contrast material) will be
injected through the catheter into your heart chamber or one of your coronary
arteries. Pictures show the arteries as the dye moves through them. You may be
asked to cough to help clear the contrast material out of your heart or breathe
deeply and hold your breath.
It is important to lie as still as
possible, since motion can make the images blurry or hard to interpret. A
health professional will help you stay comfortable and will help you resist the
urge to move around. Be careful not to touch the sheets or reach for your groin
area because you may contaminate the sterile areas and increase the risk of
infection.
Your doctor may allow you to watch the video monitor so
you can see the images of your heart and coronary arteries.
You
may be given nitroglycerin to help open up your coronary arteries. Or you may
be given an injection of a medicine (ergonovine maleate) that causes the
coronary arteries to narrow. You may be asked to breathe into a special
mouthpiece to help measure the flow of oxygen in your circulating blood.
After the test
The catheter will be removed from
the insertion site. To prevent bleeding, the site may need to be closed using
pressure, stitches, or a special seal. For example, if the catheter was
inserted in your wrist or groin, firm pressure will be applied to the area for
about 10 minutes to stop the bleeding. Then a pressure dressing will be placed
over the area. If the catheter was inserted in your elbow, a few stitches will
be used to close the wound.
The entire procedure usually takes
about one hour, but it may take longer if additional tests are required. The
length of the test is not an indication of the seriousness of your condition.
After the test, you will be taken to an observation room and a health
professional will periodically monitor your heart rate, blood pressure, and
temperature and check for signs of bleeding at the insertion site. The pulse,
color, and temperature of the arm or leg in which the catheter was inserted
will also be checked periodically.
If the catheter was inserted in
your leg, you may have to lie in bed with your leg extended for several hours
(such as 4 to 12 hours), depending on the exact procedure used and your medical
condition. After that, you can move about freely, but you should avoid
strenuous activity for at least 1 to 2 days. A child who has had cardiac
catheterization may need to be held by a parent for several hours after the
test to prevent the child from moving his or her leg.
You should
drink plenty of liquids for several hours after the test. This will prevent
dehydration and help flush the contrast material out
of your body.
Depending on the results of the test, you may be
sent home either after a short observation period (such as 6 hours) or on the
next day. If any stitches were placed in your arm, they may be removed in 5 to
7 days.