What Does an EKG Do?

An electrocardiogram-normally called an EKG or ECG-is a test that measures the electrical activity of your heart and it gives an indication to the general health of your heart. Your heart is triggered to beat by specialized cells that form the SA node-sinoatrial node-in the right atrium (the upper right chamber) of the heart. The SA node fires an electrical impulse and the heart beats. The EKG machine records the electrical activity that passes through the heart. Your doctor is able to read the pattern the EKG machine made. The doctor can determine the overall health of your heart. The EKG machine is able to show if you are having a heart attack right then in real time, and it is able to show if you have had a heart attack in the past. It can differentiate between a new and an old heart attack. The machine can also pinpoint irregularities in the heart rhythm.

Prior to your EKG test, avoid any cold beverage because the EKG machine is very sensitive and may give a false reading. Avoid excessive exercise prior to the test, because you may still have an elevated heart rate at the time of the test. An EKG test is done in doctor’s offices, hospitals and emergency rooms. Prior to the test, you are asked to disrobe and a hospital gown or disposable gown will be provided for you to put on. You will be asked to wear the gown so that it opens in the front. The technician will apply the electrodes-some machines have between 12 and 15 electrodes-to your chest, arms and legs. During the test, be as still as possible, and breathe normally. Any unnecessary movement can give a false reading.

An EKG just takes a few minutes of your time, but this test may not be conclusive in diagnosing a transient irregularity. If your EKG is within normal limits, and you have complaints of pain or irregularities in your heart rhythm that come and go, there is another type of EKG machine that you wear for 24 hours-called a Holter monitor. You go about your day and night as usual. The electrodes are applied to your chest and wires connect you to the monitor. If you have irregularities in your heart rhythm, the Holter monitor EKG machine will pick them up.

The EKG machine-including the Holter monitor-calculates your rhythm and heart rate. The doctor can see the heart rate and rhythm at the time of the test. The test can determine if a cardiac event is in progress or if you have had one in the past. The EKG can give clues to determine if your chest pain is caused by an inflammatory progress or if it is due to inadequate blood flow to the heart. Normally your heart rate is fairly constant; your doctor will look for consistencies and variations in your heart rate and rhythm-which can help your doctor diagnose or rule out the presence of heart disease.

Source: Mayo Clinic information page