Overview
Electrocardiographic procedures are non-invasive tests that
are useful to obtain a great deal of information about the heart.
These procedures record the electrical activity of the heart
and can tell a trained cardiologist a great deal of information
about the heart under many different conditions. Following is
a description of the various types of electrocardiographic procedures.
Electrocardiogram
 The electrocardiogram
(ECG; sometimes abbreviated EKG) is a non-invasive test which
records the electrical activity generated by the heart. This
electrical activity is recorded from the patient's body surface
(limbs and chest) by 10 electrodes held snugly against the skin
by elastic bands or suction cups. The test takes 5-10 minutes
to complete and yields information about the heart rhythm and
rate, hypertrophy (thickness of the heart muscle) and chamber
enlargement, presence of an old or ongoing heart attack (myocardial
infarction), or evidence of impaired blood supply (ischemia).
This is one of the most informative tests performed upon the
heart.
Exercise Electrocardiogram (Treadmill
Testing)
 The "treadmill test" obtains an electrocardiographic
record from the patient at rest, during, and after graded exercise
with the patient walking on a moving belt (treadmill). The test
not only measures exercise tolerance objectively, but also is
designed to elicit symptoms and/or electrocardiographic changes
that are brought on by exercise. The test is valuable in the
diagnosis and risk-stratification (assessment of the severity)
of patients with known or suspected coronary artery occlusive
disease (CAOD) and in selected asymptomatic patients who are
being screened for possible CAOD. The test is also valuable in
assessing the patient after recovery from a heart attack, and
in patients with known CAOD on medical therapy, or after balloon
angioplasty or coronary bypass surgery treatment.
Preparation for the Test
Do not eat or drink anything except water for three hours
before taking the test. Your physician will instruct you about
whether to take your routine medications. Either bring or wear
clothing and shoes that will be comfortable for walking. Because
you will have electrodes placed on your chest, it is best for
women to avoid wearing a dress and for men to avoid wearing
a jump suit.
The Procedure
 A nurse or exercise technologist will place electrodes on
your chest. For the clearest test results the skin will need
to be lightly scraped. Men may need to have some of their chest
hair shaved. A blood pressure cuff will also be placed on your
arm. After a resting electrocardiogram is recorded, you will
walk on the treadmill. The speed and elevation of the treadmill
will be increased at three minute intervals. While you are walking,
the technologist will monitor your heart rate, electrocardiogram,
and blood pressure (BP). The test will be stopped when you have
reached a predetermined heart rate, or at your request if you
cannot walk any further, or feel chest pain or shortness of breath.
Upon termination of exercise, you will rest on the examining
table and your electrocardiogram and BP will be monitored for
an additional 5 to 10 minute period.
Risk of the Precedure
The risk of treadmill exercise testing is very small and is
equivalent to the risk of a similar degree of exercise experienced
in the patient's daily life. The careful monitoring of the patient,
his/her blood pressure, and the continuous electrocardiographic
record, all serve to further minimize the small risk of the test.
Ambulatory Electrocardiographic
Monitoring
(Holter Monitoring)
 Patients with heart rhythm irregularities (palpitations) or
slow (bradycardia) or rapid (tachycardia) heart rhythms, which
are not documented on the routine electrocardiogram (ECG), will
usually require some type of home (ambulatory) documentation.
The holter monitor is a small compact magnetic tape electrocardiographic
recorder. Electrodes are placed firmly on the skin of the chest
beneath the patient's clothing and an ECG record of 12-24 hours
is obtained. The recorder is returned the following day and the
total ECG record is retrieved from the magnetic tape and interpreted
by the physician. This technology is helpful in the diagnosis
of paroxysmal (intermittent) rhythm disturbances and essential
for selecting proper treatment and at times for evaluating
the subsequent outcome on treatment.
Electrocardiographic Event Monitors
There are many circumstances wherein a rhythm disturbance,
or symptoms presumed to be due to a rhythm disturbance, occur
infrequently and cannot be documented during a single 24-hour
record, such as that obtained with a holter monitor. These infrequent
events require that electrocardiographic documentation be recorded
at the time of the symptoms. An electrocardiographic event monitor
is loaned to such patients for periods up to a month with instructions
regarding its simple application to the chest wall at the time
of symptoms. The electrocardiogram which is recorded is transmitted
over the telephone to a central station, from which it is transferred
to your physician for interpretation.
Medical Procedures
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