The electrocardiogram is a test that will record the electrical impulses of the heart's activity through electrodes placed on the chest, shoulders, and legs. These electrical impulses stimulate the heart to pump. If abnormalities in the impulses occur, the heart may beat irregularly or the appearance of the EKG may change shape. The information gathered from this simple test provides much preliminary data for the doctor, that will assist in diagnosing a potential heart problem or in determining what additional testing is needed to make an accurate diagnosis.