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Echocardiogram What
is Ultrasound? In each case, an ultrasound machine is used. With the help of a microphone-shaped device (known as a transducer) ultrasound waves are created and beamed through water. When the beam encounters a boundary or interface between liquid (water) and a solid (submarine or fish) with a different density or compactness, part of the beam is reflected back to the transducer. The remaining waves move through the object and reach the back boundary between solid and water. Here, some more of the ultrasound waves are reflected back to the transducer. In other words, the transducer transmits ultrasound and constantly receives waves that are reflected back every time the beam travels from one density to another. The reflected ultrasound waves are collected and
analyzed by the machine. Knowing the amount of time it took for the beam
to travel from and to the transducer, the ultrasound machine can
determine the shape, size, density and movement of all objects that lay
in the path of the ultrasound beam. The information is presented on a
monitor screen and can also be printed on paper. That is how ships
detected submarines during World War II, fishermen identify choice
fishing spots, an obstetrician can evaluate the fetus of a pregnant
woman, and a cardiologist can examine the heart of a patient. What
is an Echocardiogram: An echocardiogram is a test in which
ultrasound is used to examine the heart. The equipment is far superior
to that used by fishermen. In addition to providing single-dimension
images, known as M-mode echo that allows accurate measurement of the
heart chambers, the echocardiogram also offers far more sophisticated
and advanced imaging. This is known as two- dimensional (2-D) Echo and
is capable of displaying a cross-sectional "slice" of the
beating heart, including the chambers, valves and the major blood
vessels that exit from the left and right ventricle
An
echocardiogram can be obtained in a physician's office or in the
hospital. For a resting echocardiogram (in contrast to a stress echo or
TEE, discussed elsewhere) no special preparation is necessary. Clothing
from the upper body is removed and covered by a gown or sheet to keep
you comfortable and maintain the privacy of females. The patient then
lies on an examination table or a hospital bed Sticky patches or electrodes are attached
to the chest and shoulders and connected to electrodes or wires. These
help to record the electrocardiogram (EKG or ECG) during the
echocardiography test. The EKG helps in the timing of various cardiac
events (filling and emptying of chambers). A colorless gel is then
applied to the chest and the echo transducer 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 asked to move
from your back and to the side. Instructions may also be given for you
to breathe slowly or to hold your breath. This helps in obtaining higher
quality pictures. The images are constantly viewed on the monitor. It is
also recorded on photographic paper and on videotape. The tape offers a
permanent record of the examination and is reviewed by the physician
prior to completion of the final report. What
is a Doppler Examination? Doppler is a special part of
the ultrasound examination that assess blood flow (direction and
velocity). In contrast, the M-mode and 2-D Echo evaluates the size,
thickness and movement of heart structures (chambers, valves, etc.).
During the Doppler examination, the ultrasound beams will evaluate the
flow of blood as it makes its way through and out of the heart. This
information is presented visually on the monitor (as color images or
gray-scale tracings and also as a series of audible signals with a
swishing or pulsating sound).
What
information does Echocardiography and Doppler provide? Size
of the chambers Pumping
function Echocardiography
can also identify if the entire heart is pumping poorly due to a
condition known as cardiomyopathy (pronounced cardio-myo-puth-e),
or if one or more isolated areas have depressed movement (due to prior
heart attacks). Thus, echocardiography can assess the pumping ability
of each chamber of the heart and also the movement of each visualized
wall. The decreased movement, in turn, can be graded from mild to
severe. In extreme cases, an area affected by a heart attack may have
no movement (akinesia, pronounced a-kine-neez-ya), or may even
bulge in the opposite direction (dyskinesia, pronounced
dis-kine-neez-ya). The latter is seen in patients with aneurysm (pronounced
an-new-riz-um ) of the left ventricle or LV. It must be remembered
that LV aneurysm due to an old heart attack does not usually rupture
or "burst."
The
top diagram on the monitor shows an ultrasound beam (gray triangular
area) traveling through the right (RV) and left (LV) ventricle. You
can also see the aorta (Ao), left atrium (LA), aortic valve (AV) and
mitral valve (MV). The two pictures on the bottom of the monitor were
taken from actual patients. The arrows point to the septum or
partition between the RV and LV. The lower left picture
demonstrates normal movement of the septum as it moves towards the
opposite wall of the LV when the heart contracts. In contrast, the
patient on the bottom right has had a heart attack involving the
septum. Note that the septum moves sluggishly. Also, it is thinner and
"shriveled" as a result of the heart attack. Valve
Function:
Echocardiography identifies the structure, thickness and movement of
each heart valve. It can help determine if the valve is normal,
scarred from an infection or rheumatic fever, thickened, calcified
(loaded with calcium), torn, etc. It can also assess the function of
prosthetic or artificial heart valves.
The additional use of Doppler helps to identify
abnormal leakage across heart valves and determine their severity.
Doppler is also very useful in diagnosing the presence and severity
of valve stenosis ( pronounced stee-no-sis) or narrowing.
Remember, unlike echocardiography, Doppler follows the direction and
velocity of blood flow rather than the movement of the valve
leaflets or components.. Thus, reversed blood direction is seen with
leakages while increased forward velocity of flow with a
characteristic pattern is noted with valve stenosis.
Echocardiography is used to diagnose mitral valve
prolapse (MVP), while Doppler identifies whether it is associated
with leakage or regurgitation of the mitral valve (MR). The presence
of MVP frequently prompts the use of antibiotics prior to any dental
or non-sterile surgical procedure. Such action helps reduce the rare
complication of valve infection. Volume
status: Low
blood pressure can occur in the setting of poor heart function but
may also be seen when patient's have a reduced volume of circulating
blood (as seen with dehydration, blood loss, use of diuretics or
"water pill.", etc.). In many cases, the diagnosis can be
made on the basis of history, physical examination and blood tests.
However, confusion may be caused when patients have a combination of
problems. Echocardiography may help clarify the confusion. The
inferior vena cava (the major vein that returns blood from the lower
half of the body to the right atrium) is distended or increased in
size in patients with heart failure and reduced in caliber when the
blood volume is reduced.
Other
Uses:
Echocardiogarphy is useful in the diagnosis of fluid in the
pericardium (the sac that surrounds the heart). It also determines
when the problem is severe and potentially life-threatening. Other
diagnoses (plural for diagnosis) made by Doppler or echocardiography
include congenital heart diseases, blood clots or tumors within the
heart, active infection of the heart valves, abnormal elevation of
pressure within the lungs, etc.
How
safe is echocardiography? Echocardiography
is extremely safe. There are no known risks from the clinical use of
ultrasound during this type of testing.
How
long does it take? A brief examination in an uncomplicated case may
be done within 15 to 20 minutes. The additional use of Doppler may add
an additional 10 to 20 minutes. However, it may take up to an hour when
there are multiple problems or when there are technical problems
(for example, patients with lung disease, obesity, restlessness,
and significant shortness of breath may be more difficult to
image). When
can I expect to receive the results? If a doctor is present
during the test or reviews it while you are still in the office, you may
be able to get the results before you leave. However, the doctor is not
routinely present during the test and you may have to wait from one to
several days before the images have been reviewed by a physician and the
results are sent to you by phone or mail. Some physicians will
discuss your case before the study is performed and will contact you if
there are significant unexpected findings. For example, if you are
expected to have a finding or known to have a given disease, your
physician may indicate that he or she will call you only if there are
significant unexpected findings. You may also be contacted if
echocardiography reveals a finding that influences a change in
treatment. For example, the presence of a distended inferior vena cava
(discussed above) may result in increasing the dose of your diuretic or
water pill, if it is indicated by other aspects of your condition. If you are anxious or confused about the
results, feel free to contact the physician's office staff. They can
usually clarify the question for you. The Heart & Vascular Institute of Florida (South Care Center) |
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