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What is Cardiac Catheterization?
Cardiac catheterization is a test
used to evaluate the heart and the coronary arteries. During a
cardiac catheterization, a contrast material is injected into the
coronary arteries to trace the movement of blood. The portion of the
test involving the injection of contrast material and the tracing of
blood is called coronary angiography.
To perform cardiac catheterization,
a thin flexible tube called a catheter is threaded through a blood
vessel in the arm or groin and into the heart. Through the catheter,
your doctor can measure pressures, take blood samples, and inject
the contrast material. Movement of the dye through the heart's
chambers and blood vessels is visualized using an x-ray technique
called fluoroscopy. Fluoroscopy provides immediate ("real-time")
visualization of the x-ray images on a video monitor and provides a
permanent record of the procedure.
The purpose of cardiac
catheterization is to determine whether the coronary arteries are
diseased, and if so, identify the size and location of plaque that
may have accumulated from atherosclerosis. This is generally done to
determine the need for bypass surgery or angioplasty.
If the coronary arteries have
blockages, your doctor can use the catheter to open them and restore
normal blood flow to your heart. This is called percutaneous
coronary intervention (PCI). The three common types of PCI are
angioplasty, coronary stenting, and coronary atherectomy. These
procedures can be done separately or in conjunction.
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Angioplasty may be done by
attaching a small balloon to the catheter. Once the catheter has
been placed in the correct position in the coronary artery, the
balloon is inflated. The pressure from the inflated balloon
presses the plaque against the wall of the artery to help blood
flow more easily.
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Stenting usually is done in
conjunction with angioplasty. Once the plaque is compressed using
angioplasty, a small expandable wire tube called a stent is
inserted into the artery to hold it open. Reclosure of the artery
is less likely to occur after angioplasty followed by stenting
than after angioplasty alone. It is also common to use a type of
stent coated with drugs. These drugs help prevent scar tissue from
forming inside a stent. Studies have shown that these new stents
are more likely to prevent restenosis than ordinary, non-coated
stents.
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Atherectomy may be done during
cardiac catheterization to open a partially blocked coronary
artery. Once the catheter reaches the narrowed portion of the
artery, a cutting device, a whirling blade (such as a rotoblade),
or a laser beam is used to remove the plaque.
Why It Is Done?
Indications for the procedure
include:
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Angina that is not easily
controlled with medication, that disrupts daily routine, occurs at
rest, or recurs after heart attack
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Heart failure with suspected
coronary artery disease
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Markedly abnormal stress test
results
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Recurring chest pain with no
known cause
The primary purpose of cardiac
catheterization is to determine the severity of coronary artery
disease (CAD), and if so, whether surgery or another type of
procedure is needed to open the blocked blood vessels. Cardiac
catheterization also can be used to treat CAD by opening the blocked
vessels. The procedure is generally done only when there are
symptoms of blockage or when your doctor has reason to believe there
is a blockage and you may need treatment, such as bypass surgery or
angioplasty (and stenting).
In addition, cardiac
catheterization may be done to:
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Evaluate the pumping action of
the heart and measure pressures inside the heart and the blood
vessels.
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Determine whether a congenital
heart defect is present and evaluate its severity. Sometimes
cardiac catheterization can also be used to correct the defect.
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Evaluate blood flow through the
heart after surgery.
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Determine whether significant
heart valvular disease is present, which may require surgery.
Cardiac catheterization may also be
done in an emergency during a heart attack. A catheter is placed in
the blocked coronary artery and a balloon is inserted to open the
blocked area. In some cases, a small amount of medication to
dissolve the blood clot may be injected through the catheter to
dissolve the blood clot to help the blood to flow more smoothly.
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