An electrocardiogram (EKG or ECG) is a test that checks for problems with the electrical activity of your heart. An EKG translates the heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves. The heart is a muscular pump made up of four chambers. The two upper chambers are called atrium, and the two lower chambers are called ventricles. A natural electrical system causes the heart muscle to contract and pump blood through the heart to the lungs and the rest of the body.

An electrocardiogram (EKG, ECG) is a test that measures the electrical signals that control heart rhythm. It is called a 12-lead ECG because it examines the electrical activity of the heart from 12 points of view. This is necessary because no single point (or even 2 or 3 points of view) provides a complete picture of what is going on. The test measures how electrical impulses move through the heart muscle as it contracts and relaxes.

An electrocardiogram (EKG or ECG) is done to:

Check the heart's electrical activity.

Find the cause of unexplained chest pain, which could be caused by a heart attack, inflammation of the sac surrounding the heart (pericarditis), or angina.

Find the cause of symptoms of heart disease, such as shortness of breath, dizziness, fainting, or rapid, irregular heartbeats (palpitations).

Find out if the walls of the heart chambers are too thick (hypertrophied).

Check how well medicines are working and whether they are causing side effects that affect the heart.

Check how well mechanical devices that are implanted in the heart, such as pacemakers, are working to control a normal heartbeat.

Check the health of the heart when other diseases or conditions are present, such as high blood pressure, high cholesterol, cigarette smoking, diabetes, or a family history of early heart disease.

A patient generally lies on an examination table, and 10 electrodes (or leads) are attached to the arms, legs, and chest of the patient. The electrodes detect the electrical impulses generated by the heart, and transmit them to the ECG machine. The ECG machine produces a graph (the ECG tracing) of those cardiac electrical impulses. The electrodes are then removed. The test takes less than 5 minutes to perform.

From the ECG tracing, the following information can be obtained:

The Heart Rate.

The Heart Rhythm.

Whether there are conduction abnormalities (abnormalities in how the electrical impulse spreads across the heart).

Whether there has been a prior heart attack.

Whether there may be coronary artery disease.

Whether the heart muscle has become abnormally thickened.