Electrocardiogram
An electrocardiogram (ECG) is a test that records the electrical activity of the heart.
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.
How the test is performed:
You will be asked to lie down, and electrodes are affixed to each arm, leg and 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.
Before the ECG, tell your health care provider if you are taking any medications.
-There are no restrictions for food or fluids with the exception of cold water. It may cause sudden changes in the T wave.
-Any form of exertion (e.g climbing stairs) before an ECG may significantly increase your heart rate.
You may be asked to remove all jewelry and to wear a hospital gown.
ECG is painless. The disks may be cold and in rare circumstances. One may develop a localized rash or irritation where the patches are placed that eventually goes away.
An ECG is useful in determining whether a person has heart disease, chest pain or palpitations. If a person is on medications or on a pacemaker that may affect the heart, 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.
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
What the risks are:
There are generally no risks. The procedure merely monitors the electrical impulses and does not emit electricity, so 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 area.
The accuracy of the ECG varies with the condition being tested. Some heart conditions are not detectable at all times, 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. It is important to be relaxed and relatively warm during ECG recording. Muscle tremors such as shivering, can alter the tracing.