ECG – Electrocardiogram
Electrocardiogram – ECG records electrical signals in your heart. It is a common and painless test used to quickly detect heart problems and monitor your heart health.
Electrocardiograms – called ECGs – are often done in a doctor’s office. ECG machines are standard equipment in operating rooms and ambulances. Some personal devices, such as smartwatches, offer ECG monitoring.
If you have a family history of heart disease, your doctor may suggest an electrocardiogram as a screening test, even if you have no symptoms.
Why an ECG is done
An electrocardiogram is a painless, non-invasive way that helps diagnose many common heart problems in people of all ages. Your doctor may use an electrocardiogram to determine or detect:
- Abnormal heart rhythm (arrhythmias)
- If clogged or narrowed arteries in the heart (coronary artery disease) cause chest pain or a heart attack
- Have you had a heart attack before
- How well certain treatments for heart disease, such as pacemakers, work
You will need an ECG if you have any of the following signs and symptoms:
- Chest pain
- Dizziness or confusion
- Palpitations
- Accelerated pulse
- Shortness of breath
- Weakness, fatigue or decreased ability to exercise
If your symptoms usually come and go, they may not be noticed during a standard ECG recording. In this case, the doctor may recommend remote or continuous ECG monitoring. There are several different types.
ECG types
Holter monitor – A holter monitor is a small carrying device that records a continuous ECG, usually for 24 hours or more.
Event Monitor – This portable device is similar to a Holter monitor, but only records for a few minutes at a time. You can wear it longer than Holter for about 30 days. It works by pressing a button when you feel symptoms. Some devices automatically record when an abnormal rhythm is detected.
Risks of ECG testing
An electrocardiogram is a safe procedure. There is no risk of electric shock during the test, because the electrodes used do not produce electricity. The electrodes only record the electrical activity of your heart.
You may have less discomfort, similar to removing a bandage, when the electrodes are removed. Some people develop a mild rash where the patches are placed.
How do you prepare for an ECG
No special preparations are required for a standard electrocardiogram. Tell your doctor about any medications and supplements you are taking. This can often affect test results. The electrocardiogram is often set up and performed by a nurse or technician.
What to expect:
Before the ECG test
You may be asked to change into a hospital gown. If you have hair on the parts of the body where the electrodes will be placed, the technician may shave the region to allow the patches to stick. When you are ready, you will be asked to lie down on a test table or in bed.
During the ECG test
During the ECG, up to 12 sensors (electrodes) will be attached to the chest and limbs. The electrodes are adhesive patches with wires that connect to the monitor. They record electrical signals that make the heart beat. The computer records information and displays it in the form of waves on a monitor or on paper.
You can breathe normally during the test, but you will need to lie still. Make sure you are not cold and get ready to lie still. Movement, conversation, or shivering may skew test results. A standard ECG lasts a few minutes.
After ECG testing
You can resume normal activities after the electrocardiogram.
ECG test results
Your doctor may discuss your results as soon as he does the electrocardiogram or at the next check-up if additional tests are needed for diagnosis or treatment.
If the electrocardiogram results are correct, you may not need any other tests. If the results show an abnormality in your heart rate, you may need a new ECG test or other diagnostic tests, such as an echocardiogram. Treatment depends on what is causing your symptoms.
Your doctor will review the data recorded by the ECG machine and look for problems with your heart, including:
Heartbeat. Heart rate can usually be measured by a routine pulse check. An ECG can be helpful if your pulse is hard to feel or too fast or too irregular to count accurately. An ECG can help your doctor identify an unusually fast pulse (tachycardia) or an unusually slow heart rate (bradycardia).
Heart rate. An ECG may show irregular heart rhythms (arrhythmias). These conditions can occur when any part of the heart’s electrical system is not working properly. In other cases, beta-blockers, amphetamines, and cold and allergy medications, as well as cocaine use, can trigger arrhythmias.
Heart attack. An ECG may show evidence of a previous or ongoing heart attack. ECG patterns can indicate which part of your heart is damaged, as well as the extent of the damage.
Inadequate blood and oxygen supply to the heart. An ECG done while you have symptoms can help your doctor determine if your chest pain is caused by reduced blood flow to the heart muscle, such as chest pain due to unstable angina.
Structural abnormalities. An ECG may indicate enlargement of the chambers or walls of the heart, heart defects, and other heart problems.
If the doctor diagnoses any problems on the ECG, he may require additional tests to determine if treatment for the detected condition is necessary.