Definition and Overview

Popularly known as EKG or ECG, electrocardiogram is a common diagnostic test used to evaluate the functions of the heart. It records the electrical activity of the organ and, to a certain extent, identifies if there is abnormal blood flow or circulation. It provides a good picture of the size and shape of the heart as well.

The heart is one of the largest muscular organs of the body and is divided into four chambers. The upper chambers are called the right and left atria and below them are the right and left ventricles.

Oxygen enters into the body through the nose or mouth and combines with the blood in the lungs. The blood then travels from the lungs and proceeds to the pulmonary veins and the left atrium. It is then pumped towards the left ventricle and passes through the aorta, where it is distributed to tissues and cells.

As the oxygen is distributed and used by the body, carbon dioxide mixes with the blood for elimination. The supply goes back to the heart by entering the right atrium then proceeds to the right ventricle, where it goes through the pulmonary artery, which is connected to the lungs. The lungs expel carbon dioxide while oxygen enters into the blood supply.

As the heart pumps the blood through the chambers, it requires electrical impulse. Any interruption in the cycle can lead to a variety of cardiovascular symptoms and conditions. Issues affecting the chambers or any part of the heart may also affect the blood flow.

Who should undergo and expected results

EKG or ECG is typically performed:

  • If the patient suffers from breathlessness, chest pain, and general fatigue.
  • If there's irregular heartbeat.
  • To monitor the progression of a diagnosed heart disease. The doctor may also carry it out routinely if the patient has a family history of heart problems.
  • If a person is about to undergo surgery. An ECG or EKG is usually performed to ensure that no part of the procedure will endanger the organ.
  • To determine whether the medications or devices (such as pacemakers) used to treat or manage a heart condition are working properly or only aggravating the situation.

The test records the electrical activity through waves, which appear on a tracing paper. The results are interpreted by either a trained technician or a cardiologist.

A normal heart beats for about 60 to 100 per minute. Further, waves (or the highs and lows) should be even or consistent. Any deviation from these may indicate a potential heart problem.

There are times when the results are false positives or false negatives, depending on the heart condition present. Thus, ECG is often performed alongside other cardiovascular tests.

How the procedure works

When performed alone, ECG is conducted while the patient is at rest. It can also be performed together with a stress test.

When it is carried out in a resting state, the patient will lie down on a bed or table with the legs, arms, and chest exposed. The technician may have to remove chest hair to improve the adhesion of electrodes or pads. The areas are also cleaned. The pads are then placed on specific sections of the legs and arms. Six of them will be attached to the chest area.

The machine then records the electrical activity fed by the electrodes. The patient is not allowed to move or talk while the test is ongoing. It takes only a few minutes to complete, after which the electrodes are removed and the patient can return to normal activities unless the doctor suggests otherwise.

When it is combined with a stress test, the patient is usually asked to perform a more intense activity like running on a treadmill while the electrodes are connected to the body.

There's no special diet needed before the exam, but the patient may be requested not to drink cold water or engage in any strenuous physical activity a few hours prior to the procedure as it may interfere with the actual results.

Possible risks and complications

Electrocardiogram is a safe diagnostic test. The patient does not have to be sedated and no anesthesia is required. There may be minor discomfort when the electrodes are being removed from the body. Although rarely, some may develop allergic reactions to the pads.


  • Ganz L. Electrocardiography. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 54.
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