Table of ContentsView AllTable of ContentsPurposeRisks and LimitationsBefore the TestDuring the TestAfter the TestInterpretation
Table of ContentsView All
View All
Table of Contents
Purpose
Risks and Limitations
Before the Test
During the Test
After the Test
Interpretation
Anelectrocardiogram, also referred to as ECG or EKG, is a non-invasive test that monitors and records the electrical activity of your heart as it beats. Abnormalities in the expected electrical pattern, as displayed on a graph, can help diagnose different types of heart problems, such as atrial fibrillation, angina, and heart attack.
An ECG can also help establish if you are at risk of heart disease or monitor your response to treatment for a heart condition.
This article explains what an electrocardiogram is used for, how it is performed, and what to expect before, during, and after the test.
Verywell / Cindy Chung
Purpose of an EKG Test
An electrocardiogram records your heart’s electrical activity. With each heartbeat, the ECG will produce a consistent pattern of jagged lines on a continuous readout called a tracing. If the pattern is not consistent or falls out of the expected pattern, it could indicate that you have a heart problem.
A healthcare provider might order an ECG as part of a yearly physical examination or to screen for heart disease if:
An ECG can help determine the extent of damage if you have aheart attackand even predict your risk of a future heart attack.
An ECG may also detect heart rhythm problems liketachycardia(rapid heartbeats) orbradycardia(slowed heartbeats) so that further tests can be ordered to determine the cause.
If you are diagnosed with conditions likecoronary artery disease,heart failure, oratrial fibrillation, you may need periodic ECGs to check if you are stable and/or responding to treatment.
Types of ECG
There are three major types of ECG that have different purposes and applications:
What Are the Risks and Limitations?
The ECG is one of the most common tests in medicine because it can screen for a wide variety of heart conditions. The devices are available in most medical facilities and are relatively safe, simple, and inexpensive to perform.
Possible risks of ECG include:
An ECG also has certain limitations. Among them:
Before the ECG Test
There is not much preparation needed for an ECG.
Before the test, you will be asked to remove your top so that a series of electrodes can be applied to your body. A hospital gown will be provided. If you are undergoing a cardiac stress test, you may be asked to bring a tracksuit or similar gear to wear.
Depending on the goals of the test, you may need to stop certain medications temporarily. Inform your healthcare provider about any medications you take, including over-the-counter drugs, prescription medications, or recreational drugs. These may impact the results or the interpretation of the results.
During the ECG
Once you are changed into a hospital gown, you will lie down on an examination table. A total of 10 adhesive electrodes will be applied to your body: one on each arm and leg and six on your chest.
Each electrode is attached to the ECG machine equipped with a digital display and printer. Once the device is turned on, it will record the electrical activity of your heart, which can be viewed on the digital display. During or at the end of the test, the printer will produce the tracer.
The ECG reading will take about five minutes. During that time, you will be asked to remain still as movement can disrupt the pattern. There is no pain or discomfort associated with an ECG.
After the ECG
After the test, the electrodes are removed. Any adhesive still attached to the skin can easily be removed with an alcohol pad. You may experience some tugging of hair as the electrodes are taken off, but technicians are usually very careful about this. You can then remove the gown and put your clothes back on.
From start to finish, an ECG takes around 15 minutes (not including the waiting time in the reception). You should not have any side effects, and there are no limitations on your activity afterward.
Rarely, the adhesive can cause allergic reactions, which may not appear until up to 24 hours after the test. If you experience a rash, call your healthcare provider.
Interpreting the ECG Results
An ECG uses 10 cables that generate 12 different tracers. Each tracer shows the electrical activity from different angles of the heart.
In healthy people, a tracing will consist of a specific pattern that falls within an expected range. This not only includes the up-and-down waves (called the P wave, QRS complex, ST segment, and T wave) but also the spaces in between them (called a PR interval and QT interval).
If the pattern falls outside of the expected value, you may have a heart problem, such as:
Your ECG report may have a description of the wave pattern but is unlikely to describe your heart condition in detail. Your healthcare provider will need to take your symptoms and medical history into account when determining whether or not you have a heart condition
Sinus Arrhythmia: What’s Normal vs. Irregular
While the ECG candiagnose some heart conditionson its own (such as cardiac arrhythmias), it is more often used as a preliminary screening test. In many cases, abnormalities seen on a tracer will need to be followed with other tests to render a definitive diagnosis.
For instance, If the ECG suggests coronary artery disease,cardiac catheterizationmight be used to confirm a blocked blood vessel. If hypertrophic cardiomyopathy is suspected, an imaging test called anechocardiogrammay be ordered to view the size of the heart.
Summary
An electrocardiogram (ECG or EKG) is a common test that measures the electrical activity of your heart during heartbeats. Based on the pattern of lines on the read-out, called a tracer, a healthcare provider may be able to diagnose a heart condition, predict the risk of a heart attack, or monitor your response to heart medications.
The test involves the placement of 10 electrodes on your chest and arms, which are then connected the main ECG machine. From start to finish, the test takes around 15 minutes.
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Institute for Quality and Efficiency in Health Care.What is an electrocardiogram (ECG)?.National Library of Medicine: MedlinePlus.Electrocardiogram.Bansal A, Joshi R.Portable out-of-hospital electrocardiography: a review of current technologies.J Arrhythm. 2018;34(2):129-138. doi:10.1002/joa3.12035Sahota G, Taggar JS,Interpretation of electrocardiograms in primary care.Br J Gen Pract.2016;66(649):406. doi:10.3399/bjgp16X686293American Heart Association.Symptoms and diagnosis of cardiomyopathy.Additional ReadingGatzoulis KA, Arsenos P, Trachanas K, et al.Signal-averaged electrocardiography: past, present, and future.J Arrhythm.2018;34(3):222-229. doi:10.1002/joa3.12062
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Institute for Quality and Efficiency in Health Care.What is an electrocardiogram (ECG)?.National Library of Medicine: MedlinePlus.Electrocardiogram.Bansal A, Joshi R.Portable out-of-hospital electrocardiography: a review of current technologies.J Arrhythm. 2018;34(2):129-138. doi:10.1002/joa3.12035Sahota G, Taggar JS,Interpretation of electrocardiograms in primary care.Br J Gen Pract.2016;66(649):406. doi:10.3399/bjgp16X686293American Heart Association.Symptoms and diagnosis of cardiomyopathy.Additional ReadingGatzoulis KA, Arsenos P, Trachanas K, et al.Signal-averaged electrocardiography: past, present, and future.J Arrhythm.2018;34(3):222-229. doi:10.1002/joa3.12062
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Institute for Quality and Efficiency in Health Care.What is an electrocardiogram (ECG)?.National Library of Medicine: MedlinePlus.Electrocardiogram.Bansal A, Joshi R.Portable out-of-hospital electrocardiography: a review of current technologies.J Arrhythm. 2018;34(2):129-138. doi:10.1002/joa3.12035Sahota G, Taggar JS,Interpretation of electrocardiograms in primary care.Br J Gen Pract.2016;66(649):406. doi:10.3399/bjgp16X686293American Heart Association.Symptoms and diagnosis of cardiomyopathy.
Institute for Quality and Efficiency in Health Care.What is an electrocardiogram (ECG)?.
National Library of Medicine: MedlinePlus.Electrocardiogram.
Bansal A, Joshi R.Portable out-of-hospital electrocardiography: a review of current technologies.J Arrhythm. 2018;34(2):129-138. doi:10.1002/joa3.12035
Sahota G, Taggar JS,Interpretation of electrocardiograms in primary care.Br J Gen Pract.2016;66(649):406. doi:10.3399/bjgp16X686293
American Heart Association.Symptoms and diagnosis of cardiomyopathy.
Gatzoulis KA, Arsenos P, Trachanas K, et al.Signal-averaged electrocardiography: past, present, and future.J Arrhythm.2018;34(3):222-229. doi:10.1002/joa3.12062
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