What Happens During an Electrocardiogram?
An electrocardiogram (EKG) is painless and harmless.
A technician attaches soft, sticky patches called electrodes to the skin of
your chest, arms, and legs. The patches are about the size of a quarter.
Typically, 12 patches are attached to detect your
heart's electrical activity from many angles. To help the patches stick, the
technician may have to shave areas of your skin.
After the patches are placed on your skin, you lie
still on a table while the patches detect your heart's electrical signals. A
machine records these signals on graph paper or displays them on a screen.
The entire test takes about 10 minutes.
EKG
The illustration shows the standard
setup for an EKG. In figure A, a normal heart rhythm recording shows the
electrical pattern of a regular heartbeat. In figure B, a patient lies in a bed
with EKG electrodes attached to his chest, upper arms, and legs. A nurse
watches the painless procedure.
Special Types of Electrocardiogram
The standard EKG described above, called a resting
12-lead EKG, records only seconds of heart activity at a time. It will show a
heart problem only if the problem is present during the time that the test is
run.
Many heart problems are present all the time, and a
resting 12-lead EKG will detect them. But some heart problems, like those
related to an irregular heartbeat, can come and go. They may occur for only a
few minutes out of the day or only while you exercise.
Special EKGs, such as stress tests and Holter and
event monitors, are used to help diagnose these kinds of problems.
Stress Test
Some heart problems are easier to diagnose when your
heart is working hard and beating fast. During stress testing, you exercise to
make your heart work hard and beat fast while your heart's electrical activity
is recorded. If you're not able to exercise, you're given medicine to make your
heart work hard and beat fast.
For more information, see the Diseases and
Conditions Index article on
Stress
Testing.
Holter and Event Monitors
Holter and event monitors are small, portable
devices. They record your heart’s activity while you do your normal daily
activities. A Holter monitor records the heart’s electrical activity for
a full 24-hour period or longer.
An event monitor only records your heart’s
electrical activity at certain times while you’re wearing it. For many
event monitors, you push a button to start the monitor when you feel symptoms.
Other event monitors start automatically when they sense abnormal heart
rhythms.
For more information, see the Diseases and
Conditions Index article on
Holter
and Event Monitors. |