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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