Electrocardiographic procedures are non-invasive
tests that are useful to obtain a great deal 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 treatmentand
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.
Signal-Average
Electrocardiogram
The
Signal Average Electrocardiogram (SAE) is a very specialized type of
electrocardiogram which magnifies the heart muscle's signal (QRS) and
searches for abnormal electrical activities (late-potentials) which have a
unique relationship (perhaps a causative one) to the precipitation of rapid,
runaway heart rhythms (ventricular tachycardia). This test takes 30 to 40
minutes and is of value in some patients with dizzy spells, arrhythmias and
after heart attacks.
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.
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.
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.
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.
The
Signal Average Electrocardiogram (SAE) is a very specialized type of
electrocardiogram which magnifies the heart muscle's signal (QRS) and
searches for abnormal electrical activities (late-potentials) which have a
unique relationship (perhaps a causative one) to the precipitation of rapid,
runaway heart rhythms (ventricular tachycardia). This test takes 30 to 40
minutes and is of value in some patients with dizzy spells, arrhythmias and
after heart attacks.