An electrocardiogram (also known as an ECG or EKG) is a simple, painless test that measures your heart’s electrical activity. Every heartbeat is triggered by an electrical signal that starts at the top of your heart and travels to the bottom. Heart problems often affect the electrical activity of your heart. Your doctor may recommend an EKG if you are experiencing symptoms or signs that may suggest a heart problem, including:
- pain in your chest
- trouble breathing
- feeling tired or weak
- pounding, racing or fluttering of your heart, or a feeling that your heart is beating unevenly
- detection of unusual sounds when your doctor listens to your heart
An EKG will help your doctor determine the cause of the symptoms and signs and what type of treatment might be necessary.
If you are 50 or older, or if you have a family history of heart disease, your doctor may also order an EKG to look for early signs of heart disease.
An electrocardiogram is quick, painless, and harmless. After you change into a gown, a technician attaches 12 to 15 soft electrodes with a gel to your chest, arms, and legs. The technician may have to shave small areas to ensure the electrodes stick properly to your skin. Each electrode is about the size of quarter. These electrodes are attached to electrical leads (wires), which are then attached to the EKG machine.
During the test, you will need to lie still on a table while the machine records your heart’s electrical activity and places the information on a graph. Make sure to lie as still as possible, breathing normally. Do not talk during the test.
After the procedure, the electrodes are removed and discarded.
The entire procedure takes about 10 minutes.
An electrocardiogram records a picture of your heart’s electrical activity for the time that you are being monitored. However, some heart problems come and go. In these cases, you may need longer or more specialized monitoring.
Some heart problems only appear during exercise. During stress testing, patients have an EKG while they are performing exercise, typically on a treadmill or stationary bicycle.
Also known as an ambulatory ECG or EKG monitor, a Holter monitor records your heart’s activity over a 24 to 48 hour period while you maintain a diary of your activity to help your doctor identify the cause of your symptoms. Electrodes attached to your chest record information on a portable, battery-operated monitor that you can carry in your pocket, on your belt, or on a shoulder strap.
Symptoms that don’t happen very often may require an event recorder. It is similar to a Holter monitor, but records your heart’s electrical activity just when symptoms occur. Some event recorders activate automatically when they detect symptoms; for others, you push a button when you feel symptoms. You can send the information directly to your doctor over a phone line.
There are few, if any, risks related to an EKG. Some patients may experience a skin rash where electrodes were placed, but this usually goes away without treatment.
Patients undergoing a stress test may be at risk for heart attack, but this is related to the exercise, not the EKG.
An EKG simply monitors the electrical activity of your heart; it does not emit any electricity and is completely safe.
Avoid drinking cold water or exercising before your EKG. Drinking cold water can cause changes in the electrical patterns that the test records. Exercise can increase your heart rate and affect the test results.
If the EKG is routine and there are no pressing medical problems, your doctor will typically review the results of your EKG at a follow-up visit. Otherwise, in cases of urgent medical symptoms or findings, your doctor will be notified of the results, the EKG will be read and you should be informed of the results immediately.
An EKG can help your doctor determine if you are experiencing any of the following:
- heart rhythm problems (heart is beating too fast, too slow, or irregularly)
- heart attack (emergent) or previous heart attack
- heart defects, including enlarged heart, lack of blood flow, or birth defects
- problems with your heart’s valves
- blocked arteries (coronary artery disease)
Based on the results of an EKG, your doctor can then determine appropriate medications or treatments necessary to improve your heart’s condition.