An electrocardiogram (EKG or ECG) is a recording of the heart’s electrical activity as a graph or series of wave lines on a moving strip of paper or video monitor. The test measures the size, timing and character of the electrical impulses traveling through the heart. This allows the physician to evaluate the heart’s rate, rhythm and certain cardiac problems. 

Electrical activity that is fast, slow or otherwise abnormal can suggest various heart irregularities, disease and damage. For example, an EKG may be able to show whether a patient’s heart muscle was damaged as a result of a heart attack.

An EKG is routinely used when heart disease or damage is suspected in a patient. For example, the patient may be experiencing symptoms such as:

• Angina (chest pain) resulting from the heart not getting enough oxygen
  
  
• Strong, fast or otherwise irregular heartbeat (palpitations)
  
  
• Abnormal, fast or slow heart rhythms (arrhythmias such as atrial fibrillation)
  
  
• Shortness of breath (dyspnea)
  
  
• Lightheadedness or loss of consciousness (syncope)

The patient’s first EKG (a baseline EKG) will be compared with EKGs taken in the future, if they become necessary (e.g., after a heart attack).