An electrophysiology study (EPS) closely monitors your heart rhythm. An EPS study looks at the heart’s conduction, or electrical, system. It reveals the normal and abnormal electrical pathways of the heart. The test determines the cause of abnormal heart rhythms and assists the doctor in deciding what types of treatments are best for you.

The conduction system

The conduction system is the heart’s own internal electrical system that provides it the power to beat. The heart receives an electrical signal from the sinus node in the upper chamber or right atrium. This signal, or “spark,” starts the electrical activity. The signal then travels through the upper chambers (atria) along a standard path to the lower chambers (ventricles). This electrical circuit makes the heart contract and pump blood throughout the body. When the circuit follows this standard path, it is called normal sinus rhythm.

Arrhythmias

Arrhythmia is the term used when the electrical circuit does not follow the normal conduction path. This may result in the heart beating too slowly, too quickly or in an abnormal way. Arrhythmias caused by a delay in the conduction system make the heart beat too slowly and are called bradycardias. Arrhythmias that cause the heart to beat too rapidly are called tachycardias.

There are different types of tachycardias: 

• Supraventricular tachycardia: A fast heart rhythm that begins in the upper chambers of the heart, or atria.
• Ventricular tachycardia: A fast heart rhythm starting in the lower chambers of the heart, or ventricles.

Whether they begin in the upper or lower chambers of the heart, fast or slow heart rhythms can be disabling or even life-threatening. A cardiac electrophysiologist, a physician with special training in heart rhythm problems, performs the test.