What is an ECG or an EKG?  

An electrocardiogram (ECG or EKG) is a test that checks how your heart is functioning by measuring the electrical activity of the heart. With each heart beat, an electrical impulse (or wave) travels through your heart. This wave causes the muscle to squeeze and pump blood from the heart.

An ECG measures and records the electrical activity that passes through the heart. A doctor can determine if this electrical activity is normal or irregular.

An ECG may be recommended if you are experiencing arrhythmia, chest pain, or palpitations and an abnormal ECG result can be a signal of a number of different heart conditions.

Why is it done?
  • To detect abnormal heart rhythms that may have caused blood clots to form.
  • Detect heart problems, including a recent or ongoing heart attack, abnormal heart rhythms (arrhythmias), coronary artery blockage, areas of damaged heart muscle (from a prior heart attack), enlargement of the heart, and inflammation of the sac surrounding the heart (pericarditis).
  • Detect non-heart conditions such as electrolyte imbalances and lung diseases.
  • Monitor recovery from a heart attack, progression of heart disease, or the effectiveness of certain heart medications or a pacemaker.
  • Rule out hidden heart disease in patients about to undergo surgery.
How do you prepare?

You do not have to restrict what you eat or drink before your ECG, although it is recommended that you not smoke just before the test. You will be asked to remove your jewelry and wear a hospital gown.

What can you expect?
  • An ECG is a non-invasive procedure, which means that nothing is injected into the body.
  • It is painless.
  • A number of electrodes – usually a total of 12 to 15 – are attached to various locations on your body including your arm, leg and chest.
  • The electrodes are attached by small suction cups or adhesive patches.
  • Sensors in the pads detect the electrical activity of your heart.
  • The test is usually performed while you lie still.
  • Results are most often recorded on graph paper and interpreted or read by your doctor or a technologist.
  • The test usually takes 5 to 10 minutes.

If you require more detailed information, check with the facility where you are having your exam.

Related information

Find more information on getting an EKG from the Ottawa Heart Institute

Learn more about an exercise electrocardiogram.

How a healthy heart works