An electrocardiogram (EKG or ECG) is a routine test that records the electrical activity of the heart onto graph paper. An EKG provides doctors with information about the heart and how it is working, including information on the heart’s rhythm, its electrical conduction system, the size and function of its chambers and muscle, and blood flow to the muscle. A healthy EKG has a specific pattern. Some heart conditions cause an irregular heart beat, and changes in the normal pattern may indicate a problem. For example, during a heart attack, the EKG machine records the changing pattern of the heart’s electrical activity.

How It Works

For the heart to beat, an electrical impulse starts in the sinoatrial (SA) node in the right atrium and travels through the heart. The SA node is the heart’s natural pacemaker, and it helps the heart keep a steady beat. Small metal disks called electrodes are placed on the patient’s skin. The electrodes pick up the electrical impulses from the heart. The path of electrical energy that is sent from the SA node through the heart is recorded through the electrodes, creating a pictographic image or “tracing.” The tracing is read by the doctor.

What To Expect

For a resting EKG, the patient lies on an examination table. A technician cleans the spots for the electrodes. Some men may need to have chest hair shaved to allow a better connection. The 10 electrodes with adhesive pads are then placed on the skin of the chest, back, wrists, and ankles. The electrodes are connected to wires, called “leads,” which then connect to the EKG machine. After all connections are made, the technician enters patient information into the EKG machine and asks the patient to lie still for approximately one minute while the machine takes its readings. The test is completely safe and painless. EKG patterns are kept on file for comparison with future EKG recordings.


Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Diag/diekg.cfm
The Cleveland Clinic www.clevelandclinic.org/heartcenter/pub/guide/tests/electrocard/ecg.htm