ELECTROCARDIOGRAM (EKG)
The electrocardiogram is a means by which the innate electrical activity of the heart can be observed and recorded. Its other names are cardiogram, EKG and ECG. When used in conjunction with the patient's symptoms, examination and other laboratory tests, the EKG can be an important diagnostic tool. During emergencies and in the operating room and intensive care unit, electrocardiographic monitors are used to chart a patient's heart beat on a 24 hour basis. (The beeping machines that are so popular on TV.)
Major Indications
1) chest pain suggestive of heart disease. 2) heart attack. 3) irregular heart beat--palpitations. 4) congestive heart failure. 5) shortness of breath. 6) evaluation prior to surgery. 7) fainting/blackout spells. 8) risk factors for heart disease, i.e.high blood pressure, cholesterol, strong family history. 9) baseline test for comparison when heart symptoms develop. 10) monitoring during surgery.
Procedure
EKG's are performed in the office or at the bedside by nurses or technicians. With the patient lying on his back, metal electrodes or leads are attached to the arms, legs and chest with suction cups or straps. A conducting gel is placed beneath each electrode to facilitate the transfer of electric current from the skin. The leads connect to a machine that converts the impulses into squiggly lines on a strip of paper. Because muscular activity can obscure the heart tracing, the person being tested is asked to lie quietly while the machine is on. EKG's are painless and take only about five minutes.
Complications
There may be temporary red marks (from pressure, not burns) where the electrodes were positioned, and the gel has to be wiped off, but no serious adverse effects are associated. There is no danger from electric shock because no current goes into the patient.
What Can An EKG Tell?
The cardiogram can detect abnormalities (arrhythmias) in the rate, rhythm and regularity of the heartbeat. "Skipped" beats and extra beats are observed. The form and size of the waves produced by each heartbeat help to determine whether the person is suffering from, or had previously suffered, a heart attack or damage to the heart muscle. Among the many other disorders that may produce changes in the EKG are anginal chest pains, long-term high blood pressure, heart valve disease, diseases of the pericardium (membrane surrounding the heart), injury to the heart muscle, blood clots in the lungs, stroke, disturbances in body metabolism and medications.
Limitations
A normal electrocardiogram does not guarantee that a person has a normal heart: many cardiac disorders do not affect the heart's electrical activity. Even heart attacks occasionally do not show up on the tracing. Furthermore, because a routine EKG is only a picture of what is going on in the minute or so that the tracing is being made, it may miss abnormalities that occur sporadically or are brought on only by stress or exercise. The latter disadvantages can be overcome by the use of Holter monitoring, a 24 hour continuous tape-recorded EKG, and exercise (treadmill) tolerance testing. See the separate article for more information about exercise testing.
Cost: approx. $25-$50
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