Peripheral
Artery Occlusive Disease (PAD) & Claudication
How Can PAD Be Diagnosed?
Ankle Brachial Index Test
Duplex Ultrasound
CT Angiogram
MR Angiogram
Conventional Angiogram
Ankle Brachial Index Test
The most common test for PAD is the ankle-brachial
index (ABI), a painless exam in which a special stethoscope
is used to compare the blood pressure in your feet and arms.
Based on the results of your ABI, as well as your symptoms
and risk factors for PAD, the physician can decide if further
tests are needed. When the ABI indicates that an individual
may have PAD, other imaging techniques may be used to confirm
the diagnosis, including duplex ultrasound, magnetic resonance
angiography (MRA) and computed tomography (CT) angiography.
The
ABI is a simple, painless test to help your physician determine
if you have PAD. The blood pressure in your arms and ankles
is checked using a regular blood pressure cuff and a special
ultrasound stethoscope called a Doppler. The pressure in
your ankle is compared to the pressure in your arm to determine
how well your blood is flowing and whether further tests
are needed.
Duplex Ultrasound
What is duplex ultrasound?
Duplex ultrasound combines Doppler and conventional ultrasound
to allow physicians to see the structure of your blood vessels.
Duplex ultrasound shows how blood is flowing through your
vessels and measures the speed of the flow of blood.
Conventional ultrasound uses sound waves higher than the
human ear can detect that bounce off of blood vessels. A
computer converts the sound waves into two-dimensional, black
and white moving images.
Doppler ultrasound measures how sound waves reflect off of
moving objects. A wand bounces short bursts of sound waves
off of red blood cells and sends the information to a computer.
Doppler ultrasound produces two-dimensional color images
that show if blood flow is affected by problems in the
blood vessels.
When performing duplex ultrasound, your physician uses
the two forms of ultrasound together. The conventional
ultrasound shows the structure of your blood vessels and
Doppler ultrasound shows the movement of your red blood
cells through the vessels. Duplex ultrasound produces images
that can be color coded to show physicians where your blood
flow is severely blocked.
Your physician may recommend a duplex ultrasound to help
diagnose and examine conditions that affect the blood vessels.
These conditions include:
- Carotid occlusive disease
- Deep vein thrombosis
- Leg artery disease
- Arm artery disease
- Aortoiliac occlusive disease
- Varicose veins
- Aneurysms in your abdomen or extremities
You may have the test performed in an ultrasound lab. The
lab may be part of the physician's office or it may be in a
hospital. In some cases your vascular physician may perform
the test. Usually, however, a specially trained vascular ultrasound
technologist performs duplex ultrasound.
The test usually lasts about 30 minutes.
How do I prepare?
For most types of duplex ultrasound not involving the abdomen,
you will not have to follow any special instructions. Your
physician or the center performing the test may have specific
instructions for a particular type of duplex ultrasound.
For instance, you may have to fast overnight before having
an abdominal ultrasound. Ultrasound waves cannot break through
gas in the bowels or air in the lungs.
What happens during a duplex ultrasound?
Before the test begins, your physician or the technician
will ask you to lie on the table with your head slightly
elevated. The technician will also ask you to lie still because
any movement could change the image. The technician then
spreads a special gel over the area that he or she will examine.
The technician presses the ultrasound wand against your skin
and moves it back and forth. As the wand moves back and forth,
it sends the information to the computer that produces the
images. During the test, you may hear a whooshing sound,
which is the sound that the ultrasound machine makes to represent
your blood moving through your body.
What can I expect after a duplex ultrasound?
There are no special instructions for you to follow after
the test. You may resume all of your normal activities.
Are there any complications?
Complications are very rare with ultrasound.
CT Angiogram
What is a CT scan?
Computerized tomography scanning, also called CT or CAT scanning,
is a test that uses x rays and computers to create detailed
images of the internal structures of the body. These images,
known as CT scans, show cross-sections, or slices, of your
body. CT scanning is painless and usually takes fewer than
30 minutes.
CT scans can show the anatomy of a variety of sections
of the body, including:
- Your abdomen, which contains important blood vessels
like your abdominal aorta (your main artery) and your liver
and kidneys
- Your chest
- Your neck
- Your arms or legs
- Your brain
Your physician might order a CT scan
to help diagnose vascular conditions, tumors, infections, and
other conditions.
During a CT scan, you lie down on a table.
The table passes through a donut-shaped device. Inside the
device, a machine takes x rays in arcs around the area of
your body being examined. Tissues of varying densities absorb
these x rays. The computer assigns these densities different
numerical values and then plots an image based on these values,
mainly in shades of gray. In general, CT scans display bones
as white, gases and liquids as black, and tissues as varying
shades of gray.
Physicians may find it helpful to compare two CT scans of
the same anatomical area. One without the administration
of a dye-like material called contrast, and one with this
contrast material. Contrast material makes hollow or fluid-filled
structures more visible and highlights the presence and extent
of abnormalities, such as blood vessel abnormalities, cysts,
tumors, and abscesses.
How do I prepare?
If your test will include contrast, your physician will ask
you to avoid foods and liquids for about 4 hours before the
test. If you will be having abdominal contrast images, you
will drink a liquid version of the contrast agent 1 to 2
hours before your test.
Before the test is performed, you change into a hospital
gown and remove all jewelry and other metal objects, which
interfere with x rays. If you will be receiving a head CT
scan, you will be able to wear street clothes.
If you fear being in small, confined spaces, your physician
may give you a sedative to help you relax. If you receive
a sedative, you should arrange for a ride home after the
test.
Am I at risk for complications?
Because CT scanning is an x ray test, it sends radiation
through your body. The amount of radiation is small, but
radiation can damage body cells.
Contrast material carries a slight risk of causing an allergic
reaction. If you know that you are allergic to contrast material
or dye, let your physician know before you receive the contrast
material. The contrast material is also eliminated by the
kidneys and can affect their function, especially if you
have kidney problems already.
You may be unsuited for a CT scan if you:
- Are pregnant, because radiation may harm the fetus
- Have
an allergy to contrast dye
- Have unstable vital signs
- Weigh more than 300 pounds, because
the table cannot support the weight
- Have kidney problems
What happens during a CT scan?
If the physician chooses to
perform CT scanning with contrast, he or she will inject
the contrast material into a vein in your arm or hand. The
contrast material may make your feel flushed, warm, and mildly
sick to your stomach. This will only last for about 30 seconds.
You will lie still on the scan table that slides into
the gantry, the donut-shaped device that houses the scanning
equipment. The machine is quiet and relatively open; only
the part of the body being examined lies inside the gantry.
As a medical technician operates the scanning machine in
another room, he or she watches and speaks to you through
speakers in the CT scan room.
An x ray tube slides around the gantry, passing narrow
beams of low-dosage x rays in an arc over the body.
These beams reflect onto a detector positioned opposite the
x ray source. After the x ray source completes an arc, the
scanning table moves forward a small distance and the
x ray source transmits another arc of x rays. The detector
transmits the x ray energy to a computer, which transforms
the information about the reflected energy into an
image. To create images from different angles, the technician
adjusts the position of the scanning table.
You must remain still as the CT scanning machine operates.
The technician may ask you to hold your breath for 20 seconds
at a time, because even the motion of breathing can blur
the images. If you are being scanned for brain images,
you may rest your head on a rubber cap within a water-filled
box or within a stationary head brace.
The entire procedure usually takes 15 to 20 minutes.
What can I expect after a CT scan?
There are no restrictions after a CT scan and you can resume
normal activities immediately.
If your physician gave you a contrast agent,
you should drink fluids following the test to
speed excretion of the agent and to guard against
dehydration.
Are there any complications?
The most serious complication of CT scanning is an allergic
reaction to the contrast dye. Reactions usually
occur immediately and include flushing, itching, or difficulty
breathing or swallowing. Notify your physician
if you experience any of these symptoms. Sometimes contrast
dye leaks under your skin at the injection site. This can cause
redness, swelling, or pain.
MR Angiogram
What is Magnetic Resonance Angiography?
"Magnetic resonance angiography (MRA) uses magnetic fields
and radio waves to produce two-dimensional or three-dimensional
images of the structures inside your body, such as blood vessels.
MRA is also sometimes referred to as MRI (magnetic resonance
imaging) scanning. MRA helps your physician diagnose the following
conditions:"
- Bulges in your aorta, called aneurysms
- Tears in your
aorta, called dissections
- Problems with your heart that
you may be born with, called congenital heart disorders
- Narrowing
of the arteries in and around your kidneys, called renal
artery stenosis
- Inflammation in your blood vessels, called
vasculitis
- Hardening of the arteries (called atherosclerosis)
involving the legs or arms
- Blockages in the major arteries
that supply blood to your brain, called carotid artery disease
The MRA equipment consists of a table
that slides in and out of a donut-shaped machine. A computer
attached to the machine processes radio waves and magnetic
fields to create two-dimensional or three-dimensional images.
MRA not only helps your physician diagnose your condition,
it also helps him or her plan treatment. MRA also may, in
some circumstances, have advantages that other tests do not.
For instance, MRA does not require X-ray exposure to detect
narrowing of arteries, unlike computed tomography (CT) scans
or angiograms.
How do I prepare?
Your physician may ask you not to eat 4 to 6 hours before
the test, but usually no other preparation is necessary.
You may not be eligible for an MRA if you:
- Weigh more than 300 pounds
- Have a pacemaker or other
metallic devices inside your body, such as joints, pins,
clips, or valves
- Are on continuous life support devices,
such as oxygen
- Are pregnant
- Are claustrophobic
- Are extremely anxious, confused, or agitated
If you are claustrophobic, your physician
may recommend an open MRA.
What happens during an MRA?
Your physician will direct you to a special lab or room where
a technician will perform the test. The technician will instruct
you to change into a hospital gown and remove any jewelry
or metallic objects. The technician may give you a sedative
to make sure that you lie still during the procedure.
The technician will ask you to lie on the MRA table. The
table slides slowly through a hollow, donut-shaped chamber
that exposes you to magnetic fields and pulses of radio waves.
These magnetic fields and radio waves are harmless and painless.
The only discomfort that you may feel will be from lying
still on the hard table in an enclosed area.
During the test, the technician may speak to you through
a speaker that is inside the MRA room.
Sometimes the technician may inject a contrast dye into
your hand or forearm to improve the quality of the images.
An MRA lasts between 30 to 90 minutes.
What can I expect after an MRA?
Your physician will instruct you to arrange for a ride home
if you receive a sedative.
Are there any complications?
Complications from an MRA, such as a reaction to the contrast
dye, are very unusual.
Conventional Angiogram
What is an angiogram?
An angiogram uses x rays to view your body’s blood vessels.
Physicians often use this test to study narrow, blocked,
enlarged, or malformed arteries in many parts of your body,
including your brain, heart, abdomen, and legs. When the
arteries are studied, the test is also called an arteriogram.
If the veins are studied, it is called a venogram.
To create the x ray images, your physician will inject
a dye through a thin, flexible tube, called a catheter.
He or she threads the catheter into the desired artery
from an access point. The access point is usually in your
groin but it can also be in your arm. This dye, called
contrast, makes blood vessels visible on an x ray. Your
physician will recommend an angiogram to diagnose vascular
conditions, including:
- Blockages of the arteries outside of your heart, called
peripheral artery disease (PAD)
- Enlargements of the arteries,
called aneurysms
- Kidney artery conditions, called renovascular
conditions
- Problems in the arteries that branch off the
aorta, called aortic arch conditions
- Malformed arteries,
called vascular malformations
Sometimes physicians can also treat
a problem during an angiogram. For instance, your physician
may dissolve a clot that he or she discovers during the test.
A physician may also perform an angioplasty and stenting procedure
to clear blocked arteries during an angiogram, depending on
the location and extent of the blockage. An angiogram can also
help your physician plan operations to repair the arteries
for more extensive problems.
How do I prepare?
Your physician will perform blood tests to determine your
blood’s ability to clot and to assess your kidney function.
Based on the test results, your physician may instruct
you to stop taking aspirin or other drugs that prevent
clotting. Your physician will also tell you which medications
you should continue to take. Usually your physician will
ask you not to eat or drink anything within 6 hours of
your angiogram. Because you shouldn't drive after an angiogram,
you should arrange for a ride home.
Am I at risk for complications?
Blood clotting problems, kidney problems, and advanced age
can increase your risk for developing complications during
and after an angiogram. Allergies can increase your risk
of a reaction to the contrast dye.
What happens during an angiogram?
Your test will take place in a room equipped with a specialized
x ray machine. Your physician will insert an IV to provide
you with fluids and medications. Your physician will choose
where to insert the catheter, usually into an artery in your
groin or your elbow. Before the insertion, he or she will
clean your skin and shave any hair to reduce your risk of
infection. Your physician numbs your skin with a local anesthetic
and then makes a tiny puncture to reach the artery below. He or she
punctures your artery with a hollow needle, advances a thin wire
through the needle, threads a catheter over the wire, and
guides it to the desired location. Your physician takes x
rays that are projected on a video screen to see the catheter
as it moves through your arteries.
Once your physician has positioned the catheter properly,
he or she injects the contrast dye. The contrast causes a
brief, mild warm feeling as it enters your bloodstream. Your
physician takes more x ray images to see how the contrast
is flowing through your arteries. During the test, your physician
may ask you to hold your breath for about 5 to 15 seconds.
In addition, your physician may ask you to lie perfectly
still to prevent sudden movements from blurring the x ray
pictures.
When the test is over, your physician will remove the catheter
and press the insertion site for 10 to 20 minutes to help stop
bleeding.
Angiograms generally take about 1 hour to complete if only
xrays are required. It may take longer if your physician also
performs angioplasty and stenting.
What can I expect after an angiogram?
After the test, the medical team will monitor you for about
6 hours. During this time, you should keep the arm or leg
that was punctured straight to minimize bleeding from the
puncture site. You will also be asked to drink fluids to
prevent dehydration and flush the dye from your kidneys.
Once any bleeding from the insertion site has stopped and
your vital signs are normal, your physician will tell you
that you can leave.
At home, you can eat normally, but you should continue drinking
extra fluids for 1 to 2 days. For at least 12 hours after
the angiogram, avoid physical activities such as climbing
stairs, driving, and walking. You should be able to resume
normal activities within a day or two of the procedure.
Are there any complications?
Complications from angiography include bleeding, pain,
or swelling where the catheter was inserted, and pain,
numbness, or coolness in your arm or leg. Bruising at the
puncture site is common and usually resolves on its own.
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