What Is an Electrocardiogram
2022-07-26
Before the ECG Test
If your healthcare provider or cardiologist orders an ECG, you generally do not need to have any special tests or procedures to prepare for it. In fact, you can have it right in the healthcare provider's office if there is available time, space, and equipment. Sometimes, depending on the reason for your ECG, your healthcare provider may ask you to stop taking some of your medications for a day or two before the test.
Timing
If you are having an ECG as part of a healthcare provider's visit, anticipate needing an extra 10 to 15 minutes for the test. If you are going to have a special visit for the ECG, you should expect it to take longer because of the registration and check-in process.
Location
Often, an ECG is done in the healthcare provider's office, sometimes in the same exam room where you are seeing the healthcare provider. Your healthcare provider's clinic may have a separate space where you may need to go to have your test.
What to Wear
You will need to change into a hospital gown so that electrodes can be placed on your chest. You may be asked to remove large necklaces or chains if they dangle or get in the way, but you do not need to worry about electrical interference from metal jewelry.
Food and Drink
You can eat or drink whatever you want prior to your test. If your healthcare provider is worried that you have an especially rapid heart rhythm, you may be asked to abstain from caffeine for six to 10 hours before the test.
Cost and Health Insurance
Generally, an ECG is covered by most health insurance plans, but there are always exceptions. If you are insured and concerned that your plan may not cover the test, or if you have a plan with minimal coverage, you might want to check your benefits in advance. As with many procedures, your plan may also require you to pay a copay, and you should be able to find out by calling the number on your insurance card.
What to Bring
When you go for your ECG, you should bring your test order form (if applicable), your health insurance card, a form of identification, and a method of payment.
During the Test
Your test will be performed by a healthcare provider, a nurse, or a technician.
Throughout the Test
Each electrode is a flat, coin-shaped plate with wires attached to the ECG machine, which looks like a computer. The electrodes detect electrical activity produced by the heart and transmit this information to the machine, where it is processed and saved electronically or printed out as an ECG tracing.
Readings will be taken for about five minutes. During this time, you will be asked to remain still, as movement can disrupt the pattern. There is no pain or discomfort associated with this test.
Post-Test
After the test, the electrodes are removed. If there is any sticky material remaining, it can be easily wiped off with an alcohol pad. You may experience some pulling of hair underneath the nodes, but generally, the technicians are very careful with taking them off.
You should not expect any side effects after an ECG, and there are no limitations on your activity.
Rarely, the adhesive can cause allergic reactions or rashes, which may not be obvious until about 24 hours after the test. If you experience a rash in the area of the electrodes, call your healthcare provider.
Interpreting the ECG Results
The electrical signals generated from the electrodes are processed to obtain the heart’s electrical activity from 12 different angles, each of which shows a separate tracing. By examining any abnormalities on the ECG and which leads they are stemming from, your healthcare provider can get important clues about the status of the heart. Learning to read an ECG and recognize these patterns takes months of training and practice.
The Tracing
A tracing consists of repeated waves that have a standard shape. The waves have sections named the P wave, QRS complex, ST segment, and T wave. There is also a PR interval between the P wave and the QRS complex, and a QT interval between the QRS complex and the T wave.
Different conditions are associated with changes in the height, width, and length of these waves, and the intervals between them. A shortened QT interval, for example, can be a sign of elevated blood calcium levels.
Your ECG report may have a description of the wave pattern but is unlikely to describe your heart condition in detail. Your healthcare provider needs to take your symptoms and medical history into account when determining whether or not you could have a heart condition.
Your healthcare provider will be able to explain your results to you. Among many things, an ECG can indicate:
Heart arrhythmias, such as premature ventricular complexes or atrial fibrillation
Whether you have conduction abnormalities, which result from issues regarding how the electrical impulse spreads across the heart Signs of an ongoing or a prior myocardial infarction
Whether you have signs of severe coronary artery disease (CAD), such as stable angina or unstable angina
If your heart muscle has become abnormally thickened, as in hypertrophic cardiomyopathy
Signs of congenital electrical abnormalities, such as Brugada syndrome
Electrolyte imbalances, particularly elevated or decreased levels of potassium, calcium, or magnesium
Congenital (from birth) heart defects
Infections involving the heart, such as pericarditis, which is an infection of the protective tissue surrounding the heart
Follow-Up
While the ECG can make a clear diagnosis of some cardiac conditions, such as a cardiac arrhythmia, it is more often used as a screening test. Therefore, abnormalities seen on the ECG often need to be followed by a more definitive test in order to make a firm diagnosis.
For instance, If the ECG indicates possible coronary artery disease, a stress test or cardiac catheterization might be needed. If ventricular hypertrophy is seen, an echocardiogram is often needed to check for diseases such as aortic stenosis or other structural abnormalities.
If your healthcare provider or cardiologist orders an ECG, you generally do not need to have any special tests or procedures to prepare for it. In fact, you can have it right in the healthcare provider's office if there is available time, space, and equipment. Sometimes, depending on the reason for your ECG, your healthcare provider may ask you to stop taking some of your medications for a day or two before the test.
Timing
If you are having an ECG as part of a healthcare provider's visit, anticipate needing an extra 10 to 15 minutes for the test. If you are going to have a special visit for the ECG, you should expect it to take longer because of the registration and check-in process.
Location
Often, an ECG is done in the healthcare provider's office, sometimes in the same exam room where you are seeing the healthcare provider. Your healthcare provider's clinic may have a separate space where you may need to go to have your test.
What to Wear
You will need to change into a hospital gown so that electrodes can be placed on your chest. You may be asked to remove large necklaces or chains if they dangle or get in the way, but you do not need to worry about electrical interference from metal jewelry.
Food and Drink
You can eat or drink whatever you want prior to your test. If your healthcare provider is worried that you have an especially rapid heart rhythm, you may be asked to abstain from caffeine for six to 10 hours before the test.
Cost and Health Insurance
Generally, an ECG is covered by most health insurance plans, but there are always exceptions. If you are insured and concerned that your plan may not cover the test, or if you have a plan with minimal coverage, you might want to check your benefits in advance. As with many procedures, your plan may also require you to pay a copay, and you should be able to find out by calling the number on your insurance card.
What to Bring
When you go for your ECG, you should bring your test order form (if applicable), your health insurance card, a form of identification, and a method of payment.
During the Test
Your test will be performed by a healthcare provider, a nurse, or a technician.
Throughout the Test
Each electrode is a flat, coin-shaped plate with wires attached to the ECG machine, which looks like a computer. The electrodes detect electrical activity produced by the heart and transmit this information to the machine, where it is processed and saved electronically or printed out as an ECG tracing.
Readings will be taken for about five minutes. During this time, you will be asked to remain still, as movement can disrupt the pattern. There is no pain or discomfort associated with this test.
Post-Test
After the test, the electrodes are removed. If there is any sticky material remaining, it can be easily wiped off with an alcohol pad. You may experience some pulling of hair underneath the nodes, but generally, the technicians are very careful with taking them off.
You should not expect any side effects after an ECG, and there are no limitations on your activity.
Rarely, the adhesive can cause allergic reactions or rashes, which may not be obvious until about 24 hours after the test. If you experience a rash in the area of the electrodes, call your healthcare provider.
Interpreting the ECG Results
The electrical signals generated from the electrodes are processed to obtain the heart’s electrical activity from 12 different angles, each of which shows a separate tracing. By examining any abnormalities on the ECG and which leads they are stemming from, your healthcare provider can get important clues about the status of the heart. Learning to read an ECG and recognize these patterns takes months of training and practice.
The Tracing
A tracing consists of repeated waves that have a standard shape. The waves have sections named the P wave, QRS complex, ST segment, and T wave. There is also a PR interval between the P wave and the QRS complex, and a QT interval between the QRS complex and the T wave.
Different conditions are associated with changes in the height, width, and length of these waves, and the intervals between them. A shortened QT interval, for example, can be a sign of elevated blood calcium levels.
Your ECG report may have a description of the wave pattern but is unlikely to describe your heart condition in detail. Your healthcare provider needs to take your symptoms and medical history into account when determining whether or not you could have a heart condition.
Your healthcare provider will be able to explain your results to you. Among many things, an ECG can indicate:
Heart arrhythmias, such as premature ventricular complexes or atrial fibrillation
Whether you have conduction abnormalities, which result from issues regarding how the electrical impulse spreads across the heart Signs of an ongoing or a prior myocardial infarction
Whether you have signs of severe coronary artery disease (CAD), such as stable angina or unstable angina
If your heart muscle has become abnormally thickened, as in hypertrophic cardiomyopathy
Signs of congenital electrical abnormalities, such as Brugada syndrome
Electrolyte imbalances, particularly elevated or decreased levels of potassium, calcium, or magnesium
Congenital (from birth) heart defects
Infections involving the heart, such as pericarditis, which is an infection of the protective tissue surrounding the heart
Follow-Up
While the ECG can make a clear diagnosis of some cardiac conditions, such as a cardiac arrhythmia, it is more often used as a screening test. Therefore, abnormalities seen on the ECG often need to be followed by a more definitive test in order to make a firm diagnosis.
For instance, If the ECG indicates possible coronary artery disease, a stress test or cardiac catheterization might be needed. If ventricular hypertrophy is seen, an echocardiogram is often needed to check for diseases such as aortic stenosis or other structural abnormalities.
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