What You Can Expect During an ECG

Few procedures in medicine are easier than an ECG.

• You will lie down quietly on a bed or stretcher.
  
  
• A technician (or sometimes a nurse, doctor, or other medical professional) will place 6 small adhesive electrode pads across your chest from your lower breast bone (sternum) to an area below your left armpit. Other pads will be placed on each of your arms and legs. Insulated wires will connect each of these 10 pads to the ECG machine.
  
  
• Once these wires, called "leads," are attached, the ECG records a few heartbeats on a single sheet of graph paper.

Each heartbeat produces a set of P-QRS-T waves.

• This set of waves, in turn, is recorded and analyzed from each of 12 points of view.
  
  
• Six of these points of view are the locations of the 6 pads placed across your chest. These are called V1, V2, V3, V4, V5, and V6 (pronounced Vee One, Vee Two, and so on).
  
  
• The other points of view represent combinations of the pads placed on the arms and legs. These are called I, II, III , aVR, aVL, and aVF.
  
  
• The interpretation of the waves produced by each of these 12 views provides valuable information about the functioning of your heart.

In some circumstances, medical illnesses elsewhere in the body or various drugs (especially in overdose situations) affect an otherwise healthy heart in ways revealed by diagnostic or suggestive changes in to the ECG changes.

In addition to the 12-lead ECG, an additional "rhythm strip" may be taken. This represents only one point of view but is a good way to see important changes that may be occurring over longer periods of time.

• These may be changes that are hard to interpret or are not even detected in the handful of heartbeats recorded in the standard 12-lead ECG.
  
  
• This is especially useful when the heart is beating slower or faster than normal.

Some people with heart rhythm disorders (arrhythmias) or coronary heart disease have symptoms that come and go.

• These symptoms may include brief chest pain or angina, palpitations, dizziness, or weakness.
  
  
• If you are not having symptoms when you see your health care provider, your ECG result may be perfectly normal.
  
  
• This is a common occurrence, and it is frustrating because your health care provider cannot properly diagnose or treat your problem until it has been documented on ECG.

If this happens to you, your health care provider will probably recommend ambulatory ECG.

• This is a good way to "catch" and document any temporary or intermittent abnormalities such as irregular heartbeats.
  
  
• For this test, you are attached to an ECG recording device (sometimes called a Holter monitor) that records every heartbeat for periods of 24 hours (or longer, if necessary). An alternative method is to record the heartbeats only intermittently but for a longer period of time, days or weeks.
  
  
• Long-term monitoring significantly increases your chances of "catching" any abnormalities on the ECG, even if they last only a few minutes or seconds.