Patient Education - Lung Cancer Program at UCLA
yourself about lung cancer:
An electrocardiogram (ECG) is a test that records the electrical activity of the
ECG is used to measure the rate and regularity of heartbeats as well as the size
and position of the chambers, the presence of any damage to the heart, and the effects
of drugs or devices used to regulate the heart (such as a pacemaker). See also stress
test and Holter monitor (24h).
How the Test is Performed
You are asked to lie down, and electrodes are affixed to each arm and leg and
to your chest. This requires cleaning the site and, if necessary, shaving or clipping
hair. The standard number of leads attached is 12 to 15 for a diagnostic ECG but
may be as few as 3 to 5 for a monitoring procedure.
You are usually required to remain still, and you may be asked to hold your breath
for short periods during the procedure. Sometimes this test is performed while you
are exercising or under minimal stress to monitor changes in the heart. This type
of ECG is often called a stress test.
The results are recorded on graph paper.
How to Prepare for the Test
Before the ECG, tell your health care provider if you are taking any medications.
There are no restrictions for food or fluids. However, ingestion of cold water
immediately before an ECG may produce changes in one of the waveforms recorded (the
T wave). Exercise (such as climbing stairs) immediately before an ECG may significantly
increase your heart rate.
You may be asked to remove all jewelry and to wear a hospital gown.
How the Test Will Feel
An ECG is painless. When first applied, the disks may be cold and in rare circumstances,
you may develop a localized rash or irritation where the patches are placed.
Why the Test is Performed
An ECG is very useful in determining whether a person has heart disease. If a person
has chest pain or palpitations, an ECG is helpful in determining if the heart is
beating normally. If a person is on medications that may affect the heart or if the
patient is on a pacemaker, an ECG can readily determine the immediate effects of
changes in activity or medication levels. An ECG may be included as part of a routine
examination in patients over 40 years old.
- Heart rate: 50 to 100 beats per minute.
- Rhythm: consistent and even.
What Abnormal Results Mean
Abnormal ECG results may indicate the following:
- Myocardial (cardiac muscle) defect
- Enlargement of the heart
- Congenital defects
- Heart valve disease
- Arrhythmias (abnormal rhythms)
- Tachycardia (heart rate too fast) or bradycardia (too slow)
- Ectopic heartbeat
- Coronary artery disease
- Inflammation of the heart (myocarditis)
- Changes in the amount of electrolytes (chemicals in the blood)
- Past heart attack
- Present or impending heart attack
Additional conditions under which the test may be performed include the following:
- Alcoholic cardiomyopathy
- Anorexia nervosa
- Aortic dissection
- Aortic insufficiency
- Aortic stenosis
- Atrial fibrillation/flutter
- Atrial myxoma
- Atrial septal defect
- Cardiac tamponade
- Coarctation of the aorta
- Complicated alcohol abstinence (delirium tremens)
- Coronary artery spasm
- Digitalis toxicity
- Dilated cardiomyopathy
- Drug-induced lupus erythematosus
- Familial periodic paralysis
- Heart failure
- Hypertensive heart disease
- Hypertrophic cardiomyopathy
- Idiopathic cardiomyopathy
- Infective endocarditis
- Ischemic cardiomyopathy
- Left-sided heart failure
- Lyme disease
- Mitral regurgitation; acute
- Mitral regurgitation; chronic
- Mitral stenosis
- Mitral valve prolapse
- Multifocal atrial tachycardia
- Obstructive sleep apnea
- Paroxysmal supraventricular tachycardia
- Patent ductus arteriosus
- Bacterial pericarditis
- Constrictive pericarditis
- Post-MI pericarditis
- Peripartum cardiomyopathy
- Primary amyloid
- Primary hyperaldosteronism
- Primary hyperparathyroidism
- Primary pulmonary hypertension
- Pulmonary embolus
- Pulmonary valve stenosis
- Restrictive cardiomyopathy
- Right-sided heart failure
- Sick sinus syndrome
- Stable angina
- Systemic lupus erythematosus
- Tetralogy of Fallot
- Thyrotoxic periodic paralysis
- Transient ischemic attack (TIA)
- Transposition of the great vessels
- Tricuspid regurgitation
- Type 2 diabetes
- Unstable angina
- Ventricular septal defect
- Ventricular tachycardia
- Wolff-Parkinson-White syndrome
There are generally no risks. Because this procedure merely monitors the electrical
impulses and does not emit electricity, there is no risk of shock.
During an exercise electrocardiogram, some patients experience arrhythmias or
heart distress. Equipment for dealing with these occurrences is located in the testing
The accuracy of the ECG varies with the condition being tested. Some heart conditions
are not detectable all the time, and others may never produce any specific ECG changes.
A person who suspects heart disease or has had a heart attack may need more than
one ECG. There is no reason for healthy people to undergo annual testing unless they
have inherited risks or a medical condition.
It is important to be relaxed and relatively warm during ECG recording. Any movement,
including muscle tremors such as shivering, can alter the tracing.
Review Date: 7/17/2006
Reviewed By: Glenn Gandelman, MD, MPH, Assistant Clinical Professor of Medicine,
New York Medical College, Valhalla, NY. Review provided by VeriMed Healthcare Network.
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