A Closer Look at Electrocardiograms

Dr. Tim Doyle
Cardiologist
The Methodist Hospital

When a heart problem occurs, the heart's normal electrical activity is altered. An electrocardiogram, also called an EKG or ECG, detects and records the heart's electrical activity, allowing physicians to diagnose and treat problems. Below are some questions patients commonly ask about EKGs.

Q: In what situations is an EKG usually performed?

An EKG is frequently performed when a patient has symptoms of a heart problem. These signs often include chest pain, difficulty breathing, heart palpitations, pounding or fluttering, fatigue, nausea, or unusual sounds when a health care provider listens to the patient's heart. The test may also be used to determine how a patient's heart responds to certain medications, medical devices or activity.

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Q: How should I prepare for an EKG?

An EKG is a simple test. There are no restrictions as to food or fluids, although drinking cold water right before the test — or being cold and shivering during the test — can alter the results. Vigorous activity immediately before an EKG may also significantly increase your heart rate. Before the test, tell your health care provider about any medications you are taking. You may be asked to remove any jewelry, and to wear a hospital gown. You will be asked to lie down, and electrodes (small adhesive patches) will be placed on your arms, legs and chest.

Q: What happens during the test?

An EKG is generally painless. For a regular EKG test, you must lie still for about 10 minutes, and you may be asked to hold your breath for short periods. During that time, the machine will display the heart's electrical signals on graph paper or a screen. If your physician needs more information, you might be given additional tests. If your physician needs to monitor your heart over a longer span, you may be asked to wear a Holter monitor. This is a small device that works much like a regular EKG machine, but is portable and can monitor the heart's electrical activity for 24 hours or more.

Q: What does an EKG reveal?

An electrocardiogram can help physicians determine a variety of heart conditions. These include heart attack, lack of blood flow to the heart muscle, irregular rhythms, congenital heart defects and heart disease. According to Timothy K. Doyle, M.D., cardiologist at The Methodist Hospital, "Electrocardiograms are the starting point for the detection and monitoring of heart disease. We not only use in-office EKGs for diagnosis, but we also use portable, long-term EKGs for diagnosis of heart rhythm problems. Some of the devices are only attached to the skin intermittently, and others are worn like a hospital monitor for up to one month at a time. These long-term devices increase our sensitivity for detection of intermittent heart rhythm problems significantly."

Q: What are the risks and side effects of undergoing an EKG?

An EKG only monitors the heart's electrical activity; it doesn't send electricity into the body, so there are usually no risks. In some cases, patients may develop a rash or irritation where the electrode patches are placed. Occasionally, during an exercise EKG, a patient may experience discomfort or heart distress, so health care providers take necessary precautions and are equipped to deal immediately with such situations.