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.