Electrocardiography (EKG)
measures the
heart's
electrical activity to help evaluate its function and identify any
problems that might exist. The EKG can help determine the rate and
regularity of heartbeats, the size and position of the heart's
chambers, and whether there is any damage present.
How Is an EKG Done?
There is nothing painful about getting an EKG. Your child is
asked to lie down, and a series of small metal tabs (called
electrodes) are fixed to the skin with sticky papers. These
electrodes are placed in a standard pattern on the shoulders, the
chest, the wrists, and the ankles. After the electrodes are in
place, your child is asked to hold still and may be asked to hold
his or her breath briefly while the heartbeats are recorded for a
short period. Your child may also be asked to get up and exercise
for a while.
The information is interpreted by a machine and drawn as a
graph. The graph consists of multiple waves, which reflect the
activity of the heart. The height, length, and frequency of the
waves are read in the following way:
- The number of waves per minute on the graph is the
heart rate
.
- The distances between these waves is the
heart rhythm
.
- The shapes of the waves show how well the
heart's electrical impulses
are working, the
size of the heart
, and how well the
individual components
of the heart are working together.
- The consistency of the waves provides relatively specific
information about any
heart damage
present.
A person's heartbeat should be consistent and even. EKGs
look for abnormally slow and fast heart rates, abnormal rhythm
patterns, conduction blocks - short-circuits of the heart's
electrical impulses that cause inconsistencies in rhythm between
the upper (atrium) and lower (ventricle) areas of the heart) - and
four types of heart damage:
-
ventricular hypertrophy
- an abnormal thickening of the heart muscle
-
ischemia
- caused by an abnormally decreased
blood
supply
-
cardiomyopathies
- abnormalities in the heart muscle itself
-
electrolyte and drug disturbances
- these can alter the heart's electrochemical
environment
Computerized EKGs can be combined with other tests to provide a
multimedia account of the heart action. These additional tests
include
echocardiograms
(which are basically "ultrasound" tests that bounce sound
off the heart and use the echoes to produce an image) and
thallium scans
(which are kind of like X-rays and use a radioactive tracer,
injected into the bloodstream, to help draw a picture of the
heart).
In the past, the EKG was recorded on a machine that drew on long
strips of paper, with records from each electrode presented in a
standard sequence. Now the EKG tracings are stored as computer
files that can be called up and printed.
How Long Will it Take to Get Results?
Results of the EKG are available immediately. In fact, the EKG
machine's computer even provides an instant interpretation of
the findings as it makes the report. However, your child's
physician may also ask an expert, usually a cardiologist, to help
analyze and interpret the EKG. Reference ranges for heart rate and
the relative lengths and sizes of the various components of the
heartbeat figures vary, and diagnostic differences may be subtle,
requiring an expert eye to detect them.
Reviewed by:
Steven Dowshen, MD
Date reviewed: September 2007
Originally reviewed by:
Frederick A. Meier, MD
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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