Glossary
Some definitions from MedTerms Dictionary provided by
MedicineNet.com
Cardiac:
Having to do with the heart.
Echocardiogram: A
visual record made by echocardiography; also: the procedure for
producing such a record.
Echocardiography:
Echocardiography is a diagnostic test which uses ultrasound waves to
make images of the heart chambers, valves and surrounding structures. It
can measure cardiac output and is a sensitive test for inflammation
around the heart (pericarditis). It can also be used to detect abnormal
anatomy or infections of the heart valves.
http://www.medterms.com/script/main/art.asp?articlekey=3182
Echocardiography,
stress: A supplement to the routine exercise cardiac stress test.
During stress echocardiography, the sound waves of ultrasound are used
to produce images of the heart at rest and at the peak of exercise.
In a heart with normal blood supply, all segments of the left ventricle
(the major pumping chamber of the heart) exhibit enhanced contractions
of the heart muscle during peak exercise. Conversely, in the setting of
coronary artery disease (CAD), if a segment of the left ventricle does
not receive optimal blood flow during exercise, that segment will
demonstrate reduced contractions of heart muscle relative to the rest of
the heart on the exercise echocardiogram.
Stress echocardiography
is very useful in enhancing the interpretation of the routine exercise
cardiac stress test (ECST). It can be used to exclude significant CAD in
patients who are suspected of having a "false-positive" ECST, a falsely
abnormally result on the screening ECST test.
http://www.medterms.com/script/main/art.asp?articlekey=10280
Echocardiography,
transesophageal: A diagnostic test which is done through the
esophagus and which employs ultrasound waves to make images of the heart
chambers, valves and surrounding structures.
Transesophageal
echocardiography (TEE) may be used, for example, in the treatment of
children having heart surgery. TEE has unusually accurate imaging
capabilities that permit the identification of previously unidentified
anatomic features and postoperative surgical results that may
necessitate a change in surgical plan or surgical revision before the
child leaves the operating suite.
http://www.medterms.com/script/main/art.asp?articlekey=11488
Electrocardiogram: A
recording of the electrical activity of the heart. To take a specific
situation, the initial diagnosis of a heart attack is usually made by a
combination of clinical symptoms and characteristic electrocardiogram
(EKG) changes. The EKG can detect areas of muscle ischemia (muscle
deprived of oxygen) and/or dead tissue in the heart.
http://www.kemc.edu/e.html
Doppler ultrasound:
A form of ultrasound that can detect and measure blood flow. Doppler
ultrasound depends on the Doppler effect, a change in the frequency of a
wave resulting here from the motion of a reflector, the red blood cell.
There are several kinds of Doppler ultrasound:
Color Doppler
-- This technique estimates the average velocity of flow within a
vessel by color coding the information. The direction of blood flow
is assigned the color red or blue, indicating flow toward or away
from the ultrasound transducer.
Pulsed Doppler
-- This method allows a sampling volume or "gate" to be positioned
in a vessel visualized on the gray-scale image, and displays a graph
of the full range of blood velocities within the gate versus time.
The amplitude of the signal is approximately proportional to the
number of red blood cells and is indicated, not in color, but simply
as a shade of gray.
Power Doppler
-- This device depicts the amplitude, or power, of Doppler signals
rather than the frequency shift. This allows detection of a larger
range of Doppler shifts and thus better visualization of small
vessels, but at the expense of directional and velocity information.
Color Doppler depicts blood
flow in a region and is used as a guide for the placement of the pulsed
Doppler gate for more detailed analysis at a particular site.
Doppler ultrasound has many
applications including, for example, the detection and measurement of
decreased or obstructed blood flow to the legs. Color Doppler ultrasound
is done first to evaluate vessels rapidly for abnormalities and to guide
placement of the pulsed Doppler to gain sample volume for detailed
analysis of velocities.
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