Diagnostic Services
An electrocardiogram (ECG) is a test that records the electrical activity of the heart.
An ECG is used to measure: 
Any damage to the heart.
How fast your heart is beating and whether it is beating normally.
The effects of drugs or devices used to control the heart (such as a pacemaker).
The size and position of your heart chambers
An ECG is a very useful tool for determining whether a person has heart disease. Your doctor may order this test if you have chest pain or palpitations.
An ECG may be included as part of a routine examination in patients over age 40.