|How does the Echo Stress Test work?
How do I prepare for the test?
How is the test performed
How long does it take?
safe is it?
What is the reliability
of the test?
How quickly will
I get the results?
a panoramic view of the Echo Stress lab
does Stress Echo work? Patients with coronary
artery blockages may have minimal or no symptoms during
rest. However, symptoms and signs of heart disease may
be unmasked by exposing the heart to the stress of exercise.
During exercise, healthy coronary arteries dilate (develop
a more open channel) than an artery with a blockage.
This unequal dilation causes more blood to be delivered
to heart muscle supplied by the normal artery. In contrast,
narrowed arteries end up supplying reduced flow to it's
area of distribution. This reduced flow causes the involved
muscle to "starve" during exercise. The "starvation"
may produce symptoms (like chest discomfort or inappropriate
shortness of breath), EKG abnormalities and reduced
movement of the heart muscle. The latter can be recognized
by examining the movement of the walls of the left ventricle
(the major pumping chamber of the heart) by Echocardiography.
In the animation shown above, the
left hand panel, marked "Resting" shows normal
movement of the septum (the muscle partition between
the right and left ventricles (RV and LV, respectively)
while the patient is resting. The animated echo on the
right ("Exercise") shows that movement of
the septum is markedly reduced immediately following
stress. Such findings would indicate a blockage in the
artery supplying the partition of the heart and the
front portion of the left ventricle (both these areas
are supplied by the LAD or left anterior descending
How is a Stress Echo
performed? An Echo Stress can be obtained in
a physician's office or in the hospital. Imaging tests
are generally obtained when a physician wishes to confirm
or rule out the presence of coronary artery disease.
A Stress Echo is also performed in patients who have
disease involving the heart muscle or valve, or if a
patient is having inappropriate shortness of breath
and a cardiac cause is suspected.
is brought to the Echo laboratory where a "resting"
study is performed. This provides a baseline examination
and demonstrates the size and function of various chambers
of the heart. Particular attention is paid to the movement
of all walls of the left ventricle (LV). Similar to
a regular echo test,
sticky patches or electrodes are attached to the chest
and shoulders and connected to electrodes or wires to
record the electrocardiogram (EKG or ECG). The EKG helps
in the timing of various cardiac events (filling and
emptying of chambers).
colorless gel is then applied to the chest and the echo
transducer (as described in the Echocardiogram section)
is placed on top of it. The echo technologist then makes
recordings from different parts of the chest to obtain
several views of the heart. You may be moved from laying on your back to turning over to your left side. You may also be requested to breathe slowly or to hold your
breath. This helps to obtain higher quality pictures.
The images are constantly viewed on the monitor. It
is also recorded on photographic paper, on a CD/VCR tape and/or a computer disk.
12 leads of the EKG are recorded
on paper and the blood pressure is taken. Exercise is
then initiated using a treadmill (most common) or a
stationary bicycle. In patients who are unable to complete
a high level of exercise because of physical limitations,
stress to the heart is provided by pharmaceutical or
chemical stimulation of the heart. Stress Echo is made
up of three parts: A resting Echo study, Stress test,
and a repeat Echo while the heart is still beating fast.
Exercise stress testing usually
employs the "Bruce" or a similar protocol,
as described in the Regular
Stress Test section. Exercise is started at a slower
"warm-up" speed. The speed of the treadmill
and it's slope or inclination is increased every 3 minutes.
The treadmill is abruptly stopped when the patient exceeds
85% of the target rate (based upon the patient's age).
Exercise may be stopped earlier if the patient develops
alarming symptoms (chest discomfort, marked shortness
of breath, weakness, dizziness, etc.), if there is dangerous
elevation or drop in the blood pressure, significant
EKG changes or a potentially dangerous irregular heart
rhythm. Please remember that you have a physician in
attendance (although an experienced assistant may perform
the test if the physician is tied up with an emergency).
The above problems are uncommon and you are far safer
if they occur in the presence of an experienced medical
team rather than having them happen while you are exercising
in a spa, jogging, or running up a flight of office
EKG recordings are made during every
minute of exercise and then again after exercise is
stopped. The blood pressure is recorded at three minute
intervals during exercise and then again at rest.
Immediately after stopping the treadmill, the patient
moves directly to the examination table and lays on
the left side. The Echo examination is immediately repeated.
Images are stored and then played back by the computer.
A video clip of multiple views of the resting and exercise
study are compared side-by-side. They are analyzed by
the physician. Normally, one expects an increased EF
or ejection fraction (a measure of how well the heart
is pumping). Also, the LV walls do not show any exercise-induced
abnormal movement. In contrast, a drop in EF and/or
a new wall motion abnormality is an indicator of disease.
Preparing for the Echo
Stress Test: The following recommendations
are "generic" for all types of cardiac stress
- Do not eat or drink for three hours prior to the
procedure. This reduces the likelihood of nausea that
may accompany strenuous exercise after a heavy meal.
Diabetics, particularly those who use insulin, will
need special instructions from the physician's office.
- Specific heart medicines may need to be stopped
one or two days prior to the test. Such instructions
are generally provided when the test is scheduled.
- Wear comfortable clothing and shoes that are suitable
- An explanation of the test is provided and the patient
is asked to sign a consent form.
How long does the entire
test take? A patient should allow 1 1/2 to
2 hours for the entire test, including the preparation,
echo imaging and stress test.
How safe is a Stress Echo
test? There are no known adverse effects from
the ultrasound used during Echo imaging. The risk of
the stress portion of the test is rare and similar to
what you would expect from any strenuous form of exercise
(jogging in your neighborhood, running up a flight of
stairs, etc.). As noted earlier, experienced medical
staff is in attendance to manage the rare complications
like sustained abnormal heart rhythm, unrelieved chest
pain or even a heart attack. These problems could potentially
have occurred if the same patient performed an equivalent
level of exercise at home or on a jogging track.
What is the reliability
of Stress Echo? If a patient is able to achieve
the target heart rate and if the ECHO images are of
good technical quality, a Stress Echo is capable of
diagnosing important disease in more than 85% of patients
with coronary artery disease. Also, it can exclude important
disease in more than 90% of cases when the test is absolutely
How quickly will I get
the results and what will it mean? The physician
conducting the test will be able to give you the preliminary
results before you leave the Stress Echo laboratory.
However, the official result may take a few days to
complete. The results of the test may help confirm or
rule out a diagnosis of heart disease. In patients with
known coronary artery disease (prior heart attack, known
coronary blockages, previous treatment with angioplasty,
stents or bypass surgery, etc.), the study will help
confirm that the patient is in a stable state, or that
a new blockage is developing. The results may influence
your physician's decision to change your treatment or
recommend additional testing such as cardiac
The panoramic view
(below) shows a patient undergoing the treadmill and
Echocardiography portions of the stress test (combined
into a single picture).
You may also pan left and right by clicking
and dragging your mouse within the panoramic picture.