Cardiac catheterization is a procedure that produces special "pictures" of the
arteries that supply blood to the heart (the coronary arteries) and of the
main pumping chamber of the heart (the left ventricle). These images can
reveal if one or more of the coronary arteries is blocked or if the left ventricle
is functioning properly and pumping blood throughout the body. Additional
information can be obtained about the pressure in the different chambers of
the heart and about whether the heart valves are working normally or are
leaky or stenotic.
Who Should Have a Cardiac Catheterization?
Some cardiologists regularly treat patients with cardiac catheterization and
others treat patients with medications alone. No absolute rules exist, but
there are some general guidelines that can help guide the decision to have
cardiac catheterization.
For most patients, the primary determining factor is whether a partial or
complete blockage in the coronary arteries is present. The doctor and patient
must decide whether these blockages should be treated with angioplasty (the
balloon procedure) or bypass surgery. The patient must decide whether he or
she is willing to undergo one of these revascularization procedures. If the
patient is not willing, there is often little reason to undergo a cardiac
catheterization.
Generally accepted reasons for patients to undergo a cardiac catheterization
include the following:
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Angina pains (i.e., the discomfort from blocked coronary arteries),
which are not easily controlled with medication or that interfere daily
life
Chest pains of uncertain cause that repeatedly recur and defy
diagnosis despite other tests
Angina that occurs at rest despite medical therapy
Recurrent angina after a heart attack
Markedly abnormal stress test results
Heart failure, when the suspected cause is coronary artery disease
Disease of one or more of the heart valves causing symptoms such as
shortness of breath
Not everyone with angina needs a cardiac catheterization. Patients who have
very rare or easily controlled episodes of angina may desire to continue with
medical therapy rather than undergo angioplasty or bypass surgery. Many
patients who have suffered a heart attack can initially undergo a stress test
rather than cardiac catheterization.
The risks of cardiac catheterization are low, but sound medical reason should
always determine whether to undergo a cardiac catheterization procedure.
Risks Factors
Although cardiac catheterization is regarded as a relatively safe procedure,
complications do occasionally occur. These can include:
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Bleeding at the site of sheath insertion. This commonly produces a
small bruise in the groin, but, in rare cases, can lead to more serious
internal bleeding.
Infection at the site of sheath insertion
Damage to the blood vessels in the groin
Allergic reaction to the iodine-based dye
Kidney damage and/or kidney failure
Stroke
Heart attack
Death
Occasionally, patients have an allergic reaction to the iodine-based dye used
during cardiac catheterization. People who have had a previous reaction to
intravenous dye or who have allergies to shellfish are at increased risk for
allergic reaction. The doctor should be aware of the patient's risk for allergic
reactions before performing the procedure. Such patients usually are given a
steroid and other medications before the procedure to reduce the chance of
serious allergic reaction to the dye.
In rare cases, the dye used during the procedure can produce kidney
damage, including kidney failure requiring dialysis. People with an increased
risk for this complication include those with diabetes or preexisting kidney
disease. Patients at higher risk of dye-induced renal failure are sometimes
admitted to the hospital the night before the procedure to receive
intravenous hydration beforehand. Good hydration before and during the
procedure may decrease the chances of dye-induced kidney failure.
In general, the risk for serious complications, such as stroke, heart attack or
death, is very low — approximately one in 1000 in the general population.
Before the catheterization procedure, the doctor usually will meet with the
patient to perform an examination, ask about the patient's medical history,
and discuss the procedure and its risks. In many cases, he or she will discuss
the possibility of performing an angioplasty at the same time the
catheterization is done, should the procedure reveal one or more blockages
that require immediate treatment. These procedures typically are referred to
as a "cath possible" or "on-line" angioplasty.
Blood tests, including tests of the patient's blood counts and kidney function,
and an electrocardiogram (EKG) usually are performed on the morning of the
scheduled catheterization, although some physicians prefer to do these tests
several days before the procedure.
On the morning of the procedure, the patient typically is connected to an
intravenous (IV) line to allow for the administration of fluids, to avoid
dehydration, and for the administration of medications, if needed. Most
patients are given a Valium-type sedative before the procedure, either in pill
form or intravenously, to relax them and keep
them as comfortable as possible while the cardiac
catheterization is being performed. Patients who
do not receive a sedative should feel free to ask
the nurse or doctor for one; similarly, if the
sedative dosage does not seem to relieve anxiety,
the patient should ask for an additional dosage.
In most cases, catheterization is performed
through the patient's groin. To facilitate this, while
the patient is in a presurgical "holding area," a
nurse or technician will shave the area around the
patient's groin. At the appropriate time, the patient will be wheeled
into a specially designed laboratory and will lie down on a table. The groin
area will be wiped with a sterilizing solution. Sterile drapes will be placed
over the groin, and the area will be "numbed" by the doctor with one or two
small needle injections of the anesthetic lidocaine into the skin. A pencilsized plastic tube called a sheath is then inserted into the artery that runs
below the skin. Through it, differently shaped catheters can be passed up the
artery towards the heart and into a coronary artery (see Figure 1).
Iodine-based dye will be injected into the coronary arteries and pictures of
the arteries will be taken with a special camera. A representative angiogram
showing a tight stenosis (blockage) in the right coronary artery is shown in
Figure 2.
Another special catheter also may be inserted into the heart's left ventricle,
through which iodine-based dye can be injected. This will enable the doctor
to take pictures that show how well the left ventricle is pumping.
Injection of dye during these pictures often leads to a "hot-flash"
sensation throughout the body that lasts for 10 to 15 seconds.
Pictures of the left ventricle taken during its "relaxation" and "contraction"
phases are shown in Figure 3. The arrows indicate how the ventricle walls
have contracted to pump blood out of the left ventricle.
Additional information also may be obtained during the cardiac
catheterization. A second pencil-sized plastic sheath may be inserted through
a vein in the groin to accommodate another catheter. This can be threaded
up to and through several of the chambers of the heart to measure pressures
in different parts of the heart. It also can be used to measure the amount of
blood that the heart pumps each minute. Doctors refer to this procedure as a
"right heart catheterization."
The entire cardiac catheterization procedure can be completed in as little as
15 minutes, although it occasionally can take an hour or longer.
After the cardiac catheterization, the sheath or sheaths are removed from
the patient's groin and pressure is applied to the area — usually for 5 to 15
minutes — to close off the holes in the blood vessels that were made by
insertion of the sheaths. The patient will have to lie on his or her back for 4
to 6 hours to while normal blood clotting seals the holes in the vessels.
Several new devices are available that allow the doctor to seal the hole made
in the femoral artery immediately after the catheterization. One of these
devices, called Perclose, enables the doctor to literally sew up the hole made
in the groin. Two other devices, AngioSeal and VasoSeal, use collagen plugs
to seal holes made in the femoral artery. If either of these two methods is
used, the patient may be able to sit up within an hour of the procedure and
begin walking within several hours.
Most doctors who perform cardiac catheterization give the patient — and the
patient's family — a preliminary report on the results immediately after the
procedure is completed. Often they can tell right away whether they think
treating with medication is possible, or if angioplasty (the "balloon
procedure") or open heart surgery is necessary. Occasionally, the doctor may
want to review films taken during the procedure with other doctors before
making a final recommendation.
Most cardiac catheterizations are performed on an outpatient basis, enabling
the patient to enter the hospital early in the morning, undergo the
procedure, and go home later the same day, often in the late afternoon or
early evening. Occasionally, the doctor may feel it is advisable for the patient
to stay overnight in the hospital, so patients scheduled to undergo a cardiac
catheterization should plan to bring a small bag of select supplies, such as a
bathrobe, slippers, and toiletries, with them. In all cases, the patient should
not drive home, but should arrange for someone else to drive him or her
after the catheterization.
Before leaving the hospital, the patient will receive instructions from a doctor
or nurse regarding when and to what extent he or she can resume normal
activity. Most doctors advise against any heavy lifting or vigorous activity for
several days, principally to ensure that blood vessels in the patient's groin
heal properly. Other specific recommendations usually will depend upon what
was found during the cardiac catheterization.
A gauze dressing usually is taped to the area where the sheath or sheaths
were inserted in the patient's groin. This is left on at the time of discharge
from the hospital and usually can be removed by the patient the next
morning. Taking a shower before removing the dressing can help loosen the
tape and prevent discomfort.
For several weeks after a catheterization, a small and relatively painless
bruise or lump often is present in the area where the sheaths were inserted;
the patient should call his or her doctor promptly if pain or tenderness
develops. This can indicate infection or bleeding in the area or blood vessels
that have not sealed off properly. Other symptoms which should prompt a
call to the doctor include fever, shaking, or chills in the days after the
procedure, which can indicate infection, or pain or discoloration in the leg,
which may indicate damage to a blood vessel.