Signal Averaged Electrocardiogram (SAECG)

Why is the doctor performing this procedure?

To evaluate the heart's functioning by viewing its electrical activity. It is similar to a standard electrocardiogram (ECG), but provides greater in-depth information by collecting many heart beats and analyzing them together—a procedure called signal-averaging.

What is the procedure?

Similar to an ECG (See ECG for information on a standard electrocardiogram), the SAECG is a painless, non-invasive test, with electrodes placed on the skin. These electrodes are attached to the SAECG machine so that the electrical activity of the heart is visualized, and then electronically manipulated by the signal-averaging software for deeper analysis.

The Signal-Averaged Electrocardiogram essentially strengthens some signals while eliminating "background noise" from other signals. These signals are then filtered and averaged, providing an analysis that yields information about patient risk of future ventricular tachycardia (rapid heart activity) and/or ventricular fibrillation (irregular heart activity). These weak but very important impulses are called "late potentials" and are commonly not evaluated in a standard ECG. Late potentials arise from damaged or scarred areas of heart muscle. Recognizing the presence of these late potentials can be helpful in the following situations:

• To determine risk for ventricular arrhythmia following heart surgery or a heart attack.
• To determine the cause of fainting (called syncope).
• To determine if scar tissue is present from a previous heart attack.

Where is the procedure performed?

In the Non-Invasive Cardiology Testing Center.

How long does this procedure take?

An electrocardiogram takes 20 minutes.