An Electrophysiology study (EPS) of the heart is a test performed to analyze the electrical activity of the heart. The test uses cardiac catheters and sophisticated computers to generate electrocardiogram (EKG) tracings and electrical measurements with exquisite precision from within the heart chambers.

The normal function of the heart depends on its electrical activity, and the effect of this activity on each of its cells. When a heart is diseased, impaired electrical activity is often the factor that leads to sudden death, thus the need for EPS tests.

An EPS can be performed solely for diagnostic purposes or to pinpoint the exact location of electrical signals (cardiac mapping) in conjunction with a therapeutic procedure called catheter ablation (tissue removal). A cardiologist may recommend an EPS when the standard EKG, Holter monitor, event recorder, stress test, echocardiogram, or angiogram cannot provide enough information to evaluate an abnormal heart rhythm (arrhythmia).

An EPS offers more detailed information about the heart's electrical activity than many other noninvasive tests because electrodes are placed directly on heart tissue. This placement allows the electrophysiologist to determine the specific location of an arrhythmia and, often, to correct it during the same procedure. This corrective treatment is considered a permanent cure; in many cases, the patient may not need to take heart medications.