How does it work?
In order for your heart to beat, an electrical impulse is sent from the Sinoatrial (SA node), which is located in your heart. The SA node helps your heart keep a steady pace. An electrocardiogram can trace the path of electrical energy that is sent from the SA node and through your heart. This lets your doctor know whether you have a problem that might cause your heart to beat irregularly.
Small metal disks called Electrodes are placed on your skin. The electrodes are used to pick up the electrical impulses of the heart. The impulses are recorded, giving doctors a record of your heart’s electrical activity.
What to expect?
No special preparation is needed before you have an electrocardiogram.
During the test, you will lie on an examination table. A technician will clean the areas on your body where the electrodes will be placed, usually your chest, back, wrists, and ankles. The electrodes have wires called leads, which hook up to the electrocardiogram machine.
Once the electrodes are in place, you will be asked to lie down. The technician will enter some information into the electrocardiogram machine and then tell you to lie still for about a minute while the machine takes its readings. The test is completely safe and painless.
Purpose of test
- Helps identify inflammation or damage to the heart muscle.
- Helps identify abnormalities in the minerals that control the electrical activity of the heart.
- Helps identify various irregular rhythms (arrhythmias).
- Identifies enlargement of the various chambers of the heart.
- Identifies the site and extent of damage to the heart muscle from myocardial infarction.
- Monitors recovery from myocardial infarction.
- Monitors effectiveness of certain drugs that may affect the heart.
- Determines how well a pacemaker is functioning.
Commercial laboratory, hospital, doctor’s office by lab technician, nurse, doctor.
Risks and Precautions of Electrocardiogram
Tell your doctor if you are taking any heart medications because certain medications can affect the interpretation of the EKG.
- Activity: No changes necessary.
- Diet: Do not eat any foods or drink any beverages containing caffeine for 24 hours before the test.
- Medicines: Inform the person performing the test if you have recently taken any medications listed under. Taking these drugs may affect test results. You may be asked not to take this medication before the test.
- Disrobing: Remove all clothing. Put on surgical gown.
- Touching: Slight abrasion to the skin during preparation to attach electrodes causes mild discomfort.
- Seeing: You will see the technician, nurse or doctor, the basket or tray to hold the equipment, the needles, syringes, collecting tubes and bandages.
- Feeling: Some degree of apprehension or fear is normal and should be expected.
- Discomfort disappears when the test is finished.
- Other senses (taste, smell, hearing): Not affected.
- EKG machine, with amplifier.
- Strip–chart recorder.
- 5 lead wires.
- 4 electrodes with rubber straps.
- Suction cup chest electrodes.
- Special EKG paste or small pads soaked in alcohol or saline solution.
- 4x4 gauze pads.
- Electrodes are attached to arms, legs and chest.
- You may feel some mild discomfort during the preparation of these areas when skin is abraded.
- You must lie still and relax.
- Breathe normally during the procedure.
- Do not talk during the test because your voice may distort the EKG tracing.
- Electrode paste is wiped off with a damp cloth after test.
Test results are determined by the electrical current generated by the heart.
Current radiates from the heart in all directions. Upon reaching the skin, it is measured by electrodes connected to an amplifier and strip–chart recorder.
- Conduction defects.
- Effects of cardioactive drugs.
- Electrolyte abnormalities, such as hypokalemia.
- Myocardial infarction.
- Right–or left–bundle–branch block.
- Right or left ventricular hypertrophy.
- Sometimes an EKG only reveals abnormal wave forms during episodes of symptoms, such as angina, or during exercise.