How does an ECG test work?
Your own internal pacemaker starts your heartbeat
with an electrical signal. An EKG reads that signal
and tracks its impact on your heart as it contracts
and relaxes with each heartbeat. A computer makes
the information about your heartbeats into a wave
pattern your healthcare provider can interpret.
A heart expert (cardiologist)
usually orders or performs a traditional EKG test.
But other providers can give you this test,
especially if you’re in an ambulance or an emergency
room, or at a scheduled appointment. You can get an
EKG in your provider’s office, at a hospital or at
an outpatient facility.
How do I prepare for the test?
Before an electrocardiogram, you can eat and drink
like you normally would. But before you get dressed
on the day of your EKG test, try to:
- Avoid using oily or greasy skin creams and
lotions, because they keep electrodes from
making good contact with your skin
- Avoid full-length hosiery that prevents
electrodes from touching the skin on your legs
- Wear a shirt that you can remove easily to place
the leads on your chest
What happens during an EKG?
A healthcare provider will attach 12 electrodes with
adhesive pads to the skin on your chest, arms and
legs. They’ll put six electrodes or sensors on your
chest and six on your limbs. The sensors send
information through wires or leads, which is why
people call it a 12-lead ECG.
To allow a better connection, your provider may
shave hair that’s in the way. It takes about 10
minutes to attach the electrodes and complete the
EKG test. But the actual recording takes only 10
seconds.
For a resting EKG test, you‘ll lie flat and relax.
If you’re doing a stress test, you’ll walk on a
treadmill during the test.
A computer creates a picture (on graph paper or a
screen) of the electrical impulses traveling through
your heart. You won’t feel anything different when
the electrodes communicate with the computer.
The electrodes will stay on your skin until the EKG
test is done.
What to expect after an EKG
Your healthcare provider will remove all of the
sticky electrode patches and you can return to your
normal activities.
What does an EKG show?
When they read an EKG, your healthcare provider will
look at how much electrical activity there is and
how strong it is. They’ll also look at how much time
passes between the different waves or peaks that
represent the electrical impulses.
The parts of an electrocardiogram and what they
represent are:
- Your upper heart
chambers (atria), where your heartbeats
start, create the first wave, or “P wave.”
- Your lower heart chambers (ventricles) create
the next wave, called a QRS complex.
- The third wave, or “T wave,” shows your heart at
rest or recovering after beating.
What are the risks of this test?
An electrocardiogram is a low-risk test. It doesn’t
use radiation or put electricity into your skin. You
might have some skin irritation after your
healthcare provider removes the sticky patches that
were attached to the sensors.