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How Is Coronary Artery Disease Diagnosed?
There is no single test to diagnose coronary artery
disease (CAD). Your doctor will ask about your medical history and your
family’s medical history, assess your risk factors, and do a physical exam
and several tests. These procedures are used to:
- Decide if you have CAD
- Determine the extent and severity of the
disease
- Rule out other possible causes of your
symptoms
Based on the results of these procedures, your
doctor may order one or more of the following tests:
- EKG
(electrocardiogram). This test measures the rate and regularity of your
heartbeat.
-
Echocardiogram. This test uses sound waves to create a moving
picture of your heart. Echocardiogram provides information about the size and
shape of your heart and how well your heart chambers and valves are
functioning. The test also can identify areas of poor blood flow to the heart,
areas of heart muscle that are not contracting normally, and previous injury to
the heart muscle caused by poor blood flow.
- There are several different
types of echocardiograms, including a stress echocardiogram. During this test,
an echocardiogram is done both before and after your heart is stressed either
by having you exercise or by injecting a medicine into your bloodstream that
makes your heart beat faster and work harder. A stress echocardiogram is
usually done to find out if you have decreased blood flow to your heart (coronary
artery disease).
- Stress Test. Some heart problems are easier to
diagnose when your heart is working harder and beating faster than when it's at
rest. During stress testing, you exercise (or are given medicine if you are
unable to exercise) to make your heart work harder and beat faster while heart
tests are performed.
- During exercise stress testing,
your blood pressure and EKG readings are monitored while you walk or run on a
treadmill or pedal a bicycle. Other heart tests, such as nuclear heart scanning
or echocardiography, also can be done at the same time. These would be ordered
if your doctor needs more information than the exercise stress test can provide
about how well your heart is working.
- If you are unable to exercise, a
medicine can be injected through an intravenous line (IV) into your bloodstream
to make your heart work harder and beat faster, as if you are exercising on a
treadmill or bicycle. Nuclear heart scanning or echocardiography is then
usually done.
- During nuclear heart scanning,
radioactive tracer is injected into your bloodstream, and a special camera
shows the flow of blood through your heart and arteries. Echocardiography uses
sound waves to show blood flow through the chambers and valves of your heart
and to show the strength of your heart muscle.
- Your doctor also may order two
newer tests along with stress testing if more information is needed about how
well your heart works. These new tests are magnetic resonance imaging (MRI) and
positron emission tomography (PET) scanning of the heart. MRI shows detailed
images of the structures and beating of your heart, which may help your doctor
better assess if parts of your heart are weak or damaged. PET scanning shows
the level of chemical activity in different areas of your heart. This can help
your doctor determine if enough blood is flowing to the areas of your heart. A
PET scan can show decreased blood flow caused by disease or damaged muscles
that may not be detected by other scanning methods.
- Chest x ray. A chest x ray takes a picture of the organs and
structures inside the chest. These include the heart, lungs, and blood
vessels.
- Cardiac
catheterization. A thin, flexible tube is passed through an artery in the
groin or arm to reach the coronary arteries. The tube allows your doctor to
examine the inside of your arteries to see if there is any blockage. Your
doctor also can determine the pressure and blood flow in the heart's chambers,
collect blood samples from the heart, and examine the arteries of the heart by
x ray.
- Coronary angiography. This test is usually performed along
with cardiac catheterization. A dye that can be seen by x ray is injected
through the catheter into the coronary arteries. The doctor can see the flow of
blood through the heart and the location of blockages.
- Nuclear heart scan. This test provides your doctor with moving
pictures of the blood passing through your heart's chambers and arteries and
shows the level of blood flood to the heart muscle. A small amount of a
radioactive tracer is injected into your bloodstream through a vein, usually in
your arm. A special camera is placed in front of your chest to show where the
tracer lights up in healthy heart muscle and where it doesn't light up (in
heart muscle that has been damaged or has a blocked artery).
- There are different types of
nuclear heart scans. Most scans have two phases—taking pictures of the
heart at rest and while it is beating faster (called a stress test), although
sometimes only a rest scan is done. Many heart problems show up more clearly
when your heart is stressed than when it is at rest. By comparing the nuclear
heart scan of your heart at rest to your heart at "stress," your doctor can
determine if your heart is functioning normally or not.
- Electron beam computed tomography. This test
identifies and measures calcium buildup in and around the coronary
arteries.
Your doctor may also order the following blood
tests:
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Signs &
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