Electrophysiology Study (EPS)

Why is the doctor performing this test?

To locate the source of an abnormal heart rhythm (arrhythmia), to determine its cause, and to determine the best way to treat the arrhythmia.

What is the test?

The heart’s rhythm (or “beat cycle” or “contraction cycle”) is controlled by a natural pacemaker called the sino-atrial node (SA node). The SA node, located in the right atrium, creates an electrical impulse that travels first through the right and left atria, and then to the right and left ventricles, causing the heart to beat. Sometimes, abnormal electrical impulses occur in the heart, causing an abnormal rhythm called an arrhythmia. Arrhythmias can be too slow (bradycardias), too fast (tachycardias), or irregular. During the electrophysiology study, catheters are inserted into blood vessels in in various locations, and advanced to the heart. Through these wires, electrical impulses are both delivered to and received from the heart assessing both normal and abnormal conditions. An attempt is made to duplicate the patient’s clinical arrhythmia by pacing the heart from different locations and at different rates. Once an arrhythmia has been initiated it is assessed and analyzed to determine its origin and pathway of conduction. Once determined, a decision is made on best cause of treatment, which may include medications, ablation with radiofrequency, or even device treatment where a pacemaker or an implantable cardiac defibrillator (ICD) may be implanted. At the end of the procedure the catheters are removed and pressure is placed on the puncture site to prevent bleeding.

Where is the test performed?

In the Electrophysiology Lab (EP Lab).

How long does this test take?

An electrophysiologic study usually takes 1-4 hours.