Background
T-wave alternans is a non-invasive test that measures subtle changes in the electrical activity of the heart. The test can detect tiny heartbeat variations that can disturb one's heart rhythm and trigger sudden cardiac death. In certain individuals, particularly those who have congestive heart failure, the T-wave test has been shown to be comparable or superior to invasive tests used to determine patient risk for sudden cardiac death.

Preparation
Usually, we request that you are fasting prior to the test and wear comfortable shoes for walking on the treadmill. Generally, it is acceptable to take your cardiac medications prior to the T wave test. However, your physician may give you further information regarding special preparation. Please do not apply any lotions or ointments to your chest or back as this may interfere with the signal from the electrodes.

During the test
Please come to the EP lab on the day of your test. This test is similar to a standard electrocardiogram (ECG), with electrodes that are attached to the skin and that detect very small changes in electrical activity. You will have electrodes attached to your arms, legs, and torso, at 10 different locations. The skin on the chest needs to be bare for the electrodes to work, so hair may need to be shaved off of areas on the chest. The test will not hurt. However, some minor irritation may occur when cleaning the skin for electrode placement.

Throughout the test, your heart rate and heart rhythm will be monitored. In order to detect T-wave alternans, your heart rate must be elevated between 90 and 110 beats per minute for several minutes. Most of the time, exercise on a treadmill is used in order to increase your heart rate. Sometimes, for people with pacemakers, the heart rate can be adjusted through the pacemaker in order to perform the test. If you exercise, you will walk on the treadmill at a brisk pace for about ten minutes. The amount of time spent exercising will depend on how long it takes your heart rate to elevate to the appropriate range. After enough information is collected at a target heart rate, the treadmill will slow to a stop and you will rest for several minutes while more information is collected through the machine.

After the test, you will be allowed to leave after we verify that your vital signs are normal.