Electrocardiogram (EKG)

The electrocardiogram, or EKG, tests the heart's electrical conduction system and provides a graphic record of the electrical impulses produced during each heartbeat. The EKG is almost always the first test a patient undergoes as part of a comprehensive heart evaluation, which is performed routinely in the doctor's office. Its role in diagnosis is first to establish a baseline record for comparison with future EKGs. But often the EKG serves as the quickest route to a diagnosis when a patient is experiencing chest pain or blackouts that may be the result of heart disease.

Referred to as a "resting" or "baseline" EKG, the test only requires about 10-15 minutes and is performed with the patient lying down on a bed or examination table. A 12-lead EKG is the standard for diagnostic evaluations and requires placement of 10 electrodes. These electrodes are only sensing devices and cannot generate an electrical shock. The procedure is painless and the skin may be prepared beforehand with a jelly-like substance to promote the sending and conveyance of electrical impulses.

The EKG machine translates the electrical signals received from the heart into tracings on graph paper. These tracings, called waveforms, show how well the impulses for contraction and relaxation of the heart muscle are generated and transmitted to reveal the presence or likelihood of certain problems when the waveforms are abnormal. Abnormalities detected with the standard 12-lead electrocardiogram are not always definitive. For example, some individuals with no heart disease may produce an abnormal EKG. Further testing may be required to rule out heart disease. Additionally, a person with significant heart disease may produce a normal EKG.

Most often, the EKG is used to obtain:
  • Baseline data for comparisons with future EKGs or with findings from other tests
  • Rapid evaluation of chest pain for signs of myocardial ischemia or infarction
  • Rapid evaluation of heart rate and rhythm abnormalities

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