What is Electrocardiogram?

An electrocardiogram records the electrical signals in your heart. It’s a common test used to detect heart problems and monitor the heart’s status in many situations. Electrocardiograms — also called ECGs or EKGs — are often done in a doctor’s office, a clinic or a hospital room. And they’ve become standard equipment in operating rooms and ambulances.

An ECG is a noninvasive, painless test with quick results. During an ECG, sensors (electrodes) that can detect the electrical activity of your heart are attached to your chest and sometimes your limbs. These sensors are usually left on for just a few minutes.

Why is Electrocardiogram performed?

The purposes of an Electrocardiogram are to:

  • Check your heart rhythm
  • See if you have poor blood flow to your heart muscle (this is called ischemia)
  • Diagnose a heart attack
  • Check on things that are abnormal, such as thickened heart muscle

An Electrocardiogram is often the first test done to determine whether a person has heart disease. Your provider may order this test if:

  • You have chest pain or palpitations
  • You are scheduled for surgery
  • You have had heart problems in the past
  • You have a strong history of heart disease in the family


What should I know before receiving Electrocardiogram?

You may have minor discomfort, similar to removing a bandage, when the electrodes are removed. Rarely, a reaction to the electrode adhesive may cause redness or swelling where the patches were placed.

An electrocardiogram is a safe procedure. You’ll have no risk of getting an electrical shock during the test because the electrodes placed on your body don’t emit electricity. They only record the electrical activity of your heart.

A stress test may lead to irregular heart rhythms and, rarely, a heart attack. These effects are brought on by the exercise or medication, not the ECG itself.

An implantable loop recorder has a slight risk of infection because it involves a minor surgical procedure. And some people may experience a reaction to the device that causes inflammation.


How to prepare for Electrocardiogram?

No special preparations are necessary for a standard electrocardiogram. Do tell your doctor about any medications and supplements you’re taking because some can affect the results of your test.

What happens during Electrocardiogram?

This test takes about 5 – 10 minutes.

A technician will attach 10 electrodes with adhesive pads to the skin of your chest, arms, and legs. If you’re a guy, you may need to have your chest hair shaved to allow a better connection.

During the test you’ll lie flat while a computer creates a picture, on graph paper, of the electrical impulses that move through your heart. This is called a “resting” EKG, although the same test may be used to check your heart while you exercise.

It takes about 10 minutes to attach the electrodes and complete the test, but the actual recording takes only a few seconds.

Your doctor will keep your EKG patterns on file so that he can compare them to tests you get in the future.

Besides the standard EKG, your doctor may recommend other kinds:

  • Holter monitor. It’s a portable EKG that checks the electrical activity of your heart for 1 to 2 days, 24-hours a day. Your doctor may suggest it if he suspects you have an abnormal heart rhythm, you have palpitations, or don’t have enough blood flow to your heart muscle. Like the standard EKG, it’s painless. The electrodes from the monitor are taped to your skin. Once they’re in place, you can go home and do all of your normal activities except shower. Your doctor will ask you to keep a diary of what you did and any symptoms you notice.
  • Event monitor. Your doctor may suggest this device if you only get symptoms now and then. When you push a button, it will record and store your heart’s electrical activity for a few minutes. You may need to wear it for weeks or sometimes months. Each time you notice symptoms, you should try to get a reading on the monitor. The info is sent on the phone to your doctor, who will analyze it.
  • Signal-averaged electrocardiogram. It checks to see if you’re at high risk of getting a condition called heart arrhythmia, which can lead to cardiac arrest. The test is done in a similar way as a standard EKG, but it uses sophisticated technology to analyze your risk.

What happens after Electrocardiogram?

Your doctor will look at the waves recorded during your test to see if the impulses are traveling normally. He or she will be able to tell you the results of your ECG the same day it’s performed or at your next appointment.

If your electrocardiogram is normal, you may not need any other tests. If the results show an abnormality with your heart, you may need another ECG or other diagnostic tests, such as an echocardiogram. Treatment depends on what’s causing your signs and symptoms.

If you have any questions about the Electrocardiogram, please consult with your doctor to better understand your instructions.

Explanation of results

What do my results mean?

Because an EKG measures so many different aspects of the heart’s function, abnormal results can signify several issues. These include:

  • Defects or abnormalities in the heart’s shape and size: An abnormal EKG can signal that one or more aspects of the heart’s walls are larger than another. This can signal that the heart is working harder than normal to pump blood.
  • Electrolyte imbalances: Electrolytes are electricity-conducting particles in the body that help keep the heart muscle beating in rhythm. Potassium, calcium, and magnesium are electrolytes. If your electrolytes are imbalanced, you may have an abnormal EKG reading.
  • Heart attack or ischemia: During a heart attack, blood flow in the heart is affected and heart tissue can begin to lose oxygen and die. This tissue will not conduct electricity as well, which can cause an abnormal EKG. Ischemia, or lack of blood flow, may also cause an abnormal EKG.
  • Heart rate abnormalities: A typical human heart rate is between 60 and 100 beats per minute (bpm). An EKG can determine if the heart is beating too fast or too slow.
  • Heart rhythm abnormalities: A heart typically beats in a steady rhythm. An EKG can reveal if the heart is beating out of rhythm or sequence.
  • Medication side effects: Taking certain medications can impact a heart’s rate and rhythm. Sometimes, medications given to improve the heart’s rhythm can have the reverse effect and cause arrhythmias. Examples of medications that affect heart rhythm include beta-blockers, sodium channel blockers, and calcium channel blockers.

Depending on the laboratory and hospital, the normal range for Electrocardiogram may vary. Please discuss with your doctor any questions you may have about your test results.


Hello Health Group does not provide medical advice, diagnosis or treatment.


Review Date: October 12, 2018 | Last Modified: October 12, 2018

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