Vascular
Studies
(Carotid,
Arm, and Leg Arterial and Venous Studies, Carotid
Ultrasound, Venous Doppler Studies, Arterial Doppler
Studies, Pulse Volume Recordings, PVRS)
What
are vascular studies?
Vascular
studies are a noninvasive (the skin is not pierced)
procedure used to assess the blood flow in arteries
and veins. A transducer (like a microphone) sends
out ultrasonic sound waves at a frequency too
high to be heard. When the transducer is placed
on the skin at certain locations and angles, the
ultrasonic sound waves move through the skin and
other body tissues to the blood vessels, where
the waves echo off of the blood cells. The transducer
picks up the reflected waves and sends them to
an amplifier, which makes the ultrasonic sound
waves audible.
Vascular
studies can utilize one of these special types
of ultrasound technology, as listed below:
- Doppler ultrasound
This Doppler technique is used to measure and
assess the flow of blood through the blood vessels.
The amount of blood pumped with each beat is
an indication of the size of a vessel’s
opening. Also, Doppler can detect abnormal blood
flow within a vessel, which can indicate a blockage
caused by a blood clot, a plaque, or inflammation.
- color Doppler
Color Doppler is an enhanced form of Doppler
ultrasound technology. With color Doppler, different
colors are used to designate the direction of
blood flow. This simplifies the interpretation
of the Doppler technique.
To assess
blood flow in the limbs, pulse volume recordings
(PVRs) may be performed. Blood pressure cuffs
are inflated on the limb and blood pressure in
the limb is measured using the Doppler transducer.
To assess
the carotid arteries in the neck, a carotid duplex
scan may be performed. This type of Doppler examination
provides a 2-dimensional (2D) image of the arteries
so that the structure of the arteries and location
of an occlusion can be determined, as well as
the degree of blood flow.
A carotid
artery duplex scan is a type of vascular ultrasound
study done to assess occlusion (blockage) or stenosis
(narrowing) of the carotid arteries of the neck
and/or the branches of the carotid artery. Plaque
(a build up of fatty materials), a thrombus (blood
clot), and other substances in the blood stream
may cause a disturbance in the blood flow through
the carotid arteries.
Other
related procedures that may be used to assess
the heart and circulatory system include resting
and exercise electrocardiogram (ECG or EKG), Holter
monitor, signal-averaged ECG, cardiac catheterization,
chest x-ray, computed tomography (CT scan) of
the chest, electrophysiological studies, magnetic
resonance imaging (MRI) of the heart, myocardial
perfusion scans, radionuclide angiography, and
ultrafast CT scan. Please see these procedures
for additional information.
Vascular
conditions:
The
arteries bring oxygen and other nutrients to the
cells of the body. The veins take away the blood
after the cells have taken in the oxygen and nutrients
and given up their waste products, such as carbon
dioxide. If blood flow is decreased to any part
of the body, that area does not get enough oxygen
and nutrients and is unable to get rid of its
waste products adequately.
Decreased
blood flow can occur in the arteries and veins
anywhere in the body, such as the neck and brain.
When the neck arteries (carotid arteries) become
occluded, symptoms such as dizziness, confusion,
drowsiness, headache, and/or a brief loss of ability
to speak or move, may be the early warning signs
of a possible stroke (brain attack). More severe
symptoms, such as sudden sharp headache, loss
of vision in one eye, sudden loss of ability to
move arms, legs, or one side of the body, sudden
forceful vomiting, or sudden decreased level of
consciousness may mean that a stroke is imminent.
Some
conditions which may affect blood flow include,
but are not limited to, the following:
- atherosclerosis -
a gradual clogging of the arteries over many
years by fatty materials and other substances
in the blood stream
- aneurysm -
a dilation of a part of the heart muscle or
the aorta (the large artery that carries oxygenated
blood out of the heart to the rest of the body),
which may cause weakness of the tissue at the
site of the aneurysm
- embolus or thrombus
- clots in blood vessels may be
either an embolus (a small mass of material
such as fat globules, air, clusters of bacteria,
or even foreign matter such as a piece of metal
from a bullet) or a thrombus (a blood clot)
- inflammatory conditions
- an inflammation within a blood
vessel may occur as a result of trauma (physical
trauma, such as from a fall, or chemical trauma,
such as from an irritating medication being
introduced into the vessel), infection, or an
autoimmune disorder (e.g., polyarteritis, Raynaud's
disease, and aortic arch syndrome)
- varicose veins -
occur when the veins of the circulatory system
in the legs are exposed over time to pressure
that causes stress on the walls and valves of
the veins
Any
of these conditions may cause decreased blood
flow in arteries and/or veins. Some symptoms that
may occur when blood flow decreases to the legs
include, but are not limited to, the following:
- leg pain and/or weakness
during exertion (known as claudication)
- swelling
- soreness, tenderness,
redness, and/or warmth in the leg(s)
- pale and cool skin;
may even be grayish or blue
- numbness or tingling
- rest pain (pain in
the foot that occurs when sitting or lying down
and is relieved by standing)
If the
physician suspects that a person may have decreased
blood flow somewhere in the peripheral (arms,
legs, and/or neck) circulation, vascular studies
may be performed.
Reasons
for which vascular studies may be performed include,
but are not limited to, the following:
- evaluation of signs
and symptoms which may suggest decreased blood
flow in the arteries and/or veins of the neck,
legs, or arms
- evaluation of previous
procedures that were performed to restore blood
flow to an area
- evaluation of a vascular
dialysis device, such as an A-V fistula in the
arm
There
may be other reasons for your physician to recommend
a vascular study.
There
is no radiation used and generally no discomfort
from the application of the ultrasound transducer
to the skin.
For
some patients, having to lie still on the examination
table for the length of the procedure may cause
some discomfort or pain.
There
may be other risks depending upon your specific
medical condition. Be sure to discuss any concerns
with your physician prior to the procedure.
Certain
factors or conditions may interfere with a vascular
study. These factors include, but are not limited
to, the following:
- smoking for at least
an hour before the test, as smoking causes blood
vessels to constrict
- severe obesity
- cardiac dysrhythmias/arrhythmias
(irregular heart rhythms)
- cardiac disease
- Your physician will
explain the procedure to you and offer you the
opportunity to ask any questions that you might
have about the procedure.
- Generally, no prior
preparation, such as fasting or sedation, is
required.
- Your physician may
give you specific instructions about smoking
and consuming caffeine. You may be asked to
refrain from smoking for at least two hours
before the test, as smoking causes blood vessels
to constrict. You may also be asked to refrain
from consuming caffeine in any form for about
two hours prior to the test.
- Based upon your medical
condition, your physician may request other
specific preparation.
A vascular
study may be performed on an outpatient basis
or as part of your stay in a hospital. Procedures
may vary depending on your condition and your
physician's practices.
Generally,
a vascular study follows this process:
- You will be asked to
remove any jewelry or other objects that may
interfere with the procedure. You may wear your
glasses, dentures, or hearing aid if you use
any of these.
- If you are asked to
remove clothing, you will be given a gown to
wear.
- You will lie on an
exam table or bed.
- A clear gel will be
placed on the skin at locations where the pulse
is expected to be heard.
- The Doppler transducer
will be pressed against the skin and moved around
over the area of the artery or vein being studied.
- When blood flow is
detected, you will hear a "whoosh, whoosh" sound.
The probe will be moved around to compare blood
flow in different areas of the artery or vein.
- For arterial studies
of the legs, blood pressure cuffs will be applied
in three positions on the leg in order to compare
the blood pressure between different areas of
the leg. The cuff around the thigh will be inflated
first, and the blood pressure will be determined
with the Doppler transducer placed just below
the cuff.
- The cuff around the
calf will be inflated, and the blood pressure
will be determined as with the thigh cuff.
- The cuff around the
ankle will be inflated, and the blood pressure
will be determined as in steps #6 and #7.
- The blood pressure
will be taken in the arm on the same side as
the leg that was just studied and used to determine
the degree of any occlusion of arterial flow
in the legs.
- Once the procedure
has been completed, the gel will be removed
from the skin.
The
technologist will use all possible comfort measures
and complete the procedure as quickly as possible
to minimize any discomfort.
You
may resume your usual diet and activities unless
your physician advises you differently.
Generally,
there is no special type of care following a vascular
study. However, your physician may give you additional
or alternate instructions after the procedure,
depending on your particular situation.
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