​Children's Heart Center


An electrocardiogram, also called ECG or EKG, is one of the simplest and fastest procedures used to evaluate the heart. The electrical activity of the heart is measured by an electrocardiogram. Changes in an EKG from the normal tracing can indicate one or more of several heart-related conditions.


Electrocardiograms are often useful in diagnosing patients with these conditions:

  • Conditions in which the heart is enlarged – These conditions can be caused by various factors, such as congenital heart defects, valve disorders, high blood pressure, congestive heart failure or conduction disturbances.
  • Ischemia – Decreased blood flow to the heart muscle due to clogged or partially-clogged arteries
  • Conduction disorders – A dysfunction in the heart’s electrical conduction system that can make the heart beat too fast, too slow or at an uneven rate
  • Electrolyte disturbances – An imbalance in the level of electrolytes in the blood, such as potassium, magnesium or calcium
  • Pericarditis – An inflammation or infection of the sac which surrounds the heart
  • Valve disease – Malfunction of one or more of the heart valves that may cause an obstruction of the blood flow within the heart
  • Chest trauma – Blunt trauma to the chest, such as a motorist hitting the steering wheel in an automobile accident

NOTE: This list is not intended to be a comprehensive list of conditions that may cause EKG changes.

An EKG may also be performed for other reasons:

  • During a physical examination to obtain a baseline tracing of the heart’s function. (This baseline tracing may be used later as a comparison with future EKGs to see if any changes have occurred.)
  • As part of a work-up prior to a procedure such as surgery to make sure no heart condition exists that might cause complications during or after the procedure
  • To check the function of an implanted pacemaker
  • To check the effectiveness of certain heart medications
  • To check the heart’s status after a heart-related procedure, such as a cardiac catheterization, heart surgery or electrophysiological studies

Performing an Electrocardiogram

An electrocardiogram can be performed almost anywhere. EKG’s may be performed in a physician’s office, clinic exam room, a specialized hospital department, the emergency department or even in a hospital patient room. The average time required to perform the exam ranges from 10 to 20 minutes.

During an EKG:

  • The patient will lie flat on a table or bed for the procedure.
  • The patient’s chest will be uncovered to perform the test. Patient privacy will be maintained by covering the patient with a sheet or gown to limit exposure to only that area of the body necessary to accomplish the exam.
  • Multiple skin electrodes will be attached to the patient’s chest, and one electrode will be attached to each arm and leg. Special lead wires are then attached to the skin electrodes.
  • It is important for the patient to lie still and not talk during the exam to minimize the potential for external interference with the tracing. For infants and children, parents are encouraged to be present in the room to reassure the patient and help them remain still.
  • Once the tracing is completed, the leads are disconnected, the electrodes removed and the skin cleaned.
  • The tracing is then transmitted for analysis, measuring, interpretation and reporting.