What Is an Echocardiogram (Echo Test)?
Echocardiography, also known as an echo test, is an ultrasound
examination of your heart to assess the function of the heart
structures (see Table 1 below). Sound waves create a moving
picture of your heart, giving us information about its size and shape,
and how well your heart chambers and valves are working.
An echocardiogram is noninvasive (the skin is not pierced). Also,
the procedure is used as a safe method of assessing heart function.
Because the patient is not exposed to radiation during an
echocardiogram, the procedure is suitable for repeated measurements
over time.
Resting and exercise during an echocardiogram
During the resting portion procedure, 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 chest at certain
locations and angles, the ultrasonic sound waves move through the skin
and other body tissues to the heart tissues, where the waves echo off
of the heart structures. This is why an echocardiogram is also called
an echo test.
The transducer picks up the reflected waves and sends them to a
computer. The computer interprets the echoes into an image of the
heart walls and valves.
After the resting echocardiogram images have been obtained, the
person will begin to exercise on a treadmill or stationary bicycle.
The physician will compare the resting echocardiogram with the test
done immediately after exercise. If a patient is unable to exercise
for any reason, the doctor may decide to perform a dobutamine
stress echocardiogram, in which dobutamine is administered to
mimic the effects of exercise on the heart.
Echocardiographic measurements
The function of the left ventricle is one of the most important
measurements that is made during an echocardiogram. The ejection
fraction, or EF, is a common measure of the function of the left
ventricle, the main pumping chamber that pumps blood to the entire
body. The ejection fraction is the percentage of blood pumped out with
each heart beat. The ejection fraction is calculated by the dividing
the total amount of blood that fills the main heart chamber by the
amount of blood pumped out with each heart beat. The normal ejection
fraction is about 60%.
