This page was reviewed under our medical and editorial policy by

Faizi A. Jamal, MD, Cardiologist, City of Hope | Duarte

This page was reviewed on June 1, 2023.

What is an EKG?

An electrocardiogram (EKG) is a simple, noninvasive test that shows how well your heart functions. It measures the electrical signals that travel through your heart with each beat.

Before beginning cancer treatment, your doctor may order an EKG to check on your heart’s strength. Your doctor may also order an EKG during and after cancer treatment to monitor for possible damage.

The test is performed using a machine known as an electrocardiograph, which records your heart’s electrical activity and prints it out on a graph for the doctor to see. A normal heart beats 60 to 100 times a minute. Your doctor looks at the rhythm and wave pattern on the graph for any irregularities.

Is it EKG or ECG?

Both of these abbreviations refer to an electrocardiogram. EKG, based on the German spelling (elektrokardiogramm), is often preferred to avoid confusion with another test, EEG (electroencephalogram), which measures brain waves.

How an EKG is performed

An EKG is typically performed in your doctor’s office or a hospital and lasts about 10 minutes.

The test is done with you lying flat on an examination table. What to expect:

  • A nurse attaches small sensors (electrodes) to your arms, legs and chest. Because the sensors stick to your skin, you may need to be shaved.
  • The electrodes are attached to the electrocardiograph with wires. The examiner is able to see the activity (wavy lines) it records by looking at a computer screen or the graph it prints out.
  • You may be asked to hold your breath (usually for no more than a few seconds at a time) to get a better reading.
  • You may be asked to relax your muscles. The less you move, the better the results.
  • There’s no recovery period after the test. Most patients are able to resume normal activities, including driving, right away.
  • A doctor reviews the results and may discuss what they mean with you afterward.

How to prepare for an EKG

When scheduling your appointment, be sure to discuss:

  • Medications you take—Ask your doctor whether you should take them before your test.
  • Insurance and cost—Ask your health insurance carrier what the exam costs and how much is covered.

On the day of your appointment:

  • Avoid using powders or lotions on your chest area, because it’ll make it harder to stick the electrodes to your skin.
  • Wear a shirt or top that’s easy to remove. The person setting up the exam needs to be able to attach the electrodes directly to your skin.
  • Don’t wear jewelry, especially necklaces or pendants that may get in the way.

What does an EKG show?

Cancer treatment, especially chemotherapy and radiation, may affect the heart. An EKG shows whether the patient has:

  • An irregular heartbeat
  • Damage to the heart muscle or tissue
  • Any changes in the thickness of the heart muscle or chamber walls
  • Any imbalances in chemicals or electrolytes in the body

Possible risks

Because it’s noninvasive and simple, there’s little risk to having an EKG. An EKG records electricity, but it doesn’t send electricity through your body. Your skin may be irritated where the electrodes are attached, but that shouldn’t last long.

What is an echocardiogram?

Your doctor may order an echocardiogram (echo) as well as an EKG to monitor your heart. They are often done at the same time.

An echo is an ultrasound of the heart. Like an EKG, an echo is painless and noninvasive. It uses a machine that measures sound waves that “echo” back. An echo may identify:

  • Blood clots in the heart
  • Damage from heart attacks
  • Tumors in the heart
  • Infections in the heart
  • Heart valve problems
  • Heart pumping function

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