An EP study is a low risk procedure that has been performed in major medical centres for many years. The EP study makes it possible to study your abnormal heart rhythm under controlled conditions and diagnose your particular problem. In this procedure, one or more thin, flexible wires, called catheters are inserted into a blood vessel usually the groin) and guided into the heart. Each catheter has two or more electrodes to measure the heart’s electrical signals as they travel from one chamber to another. EP study is usually done under local anaesthesia.
An EP Study offers more detailed information about the heart’s electrical activity than many other noninvasive tests because electrodes are placed directly on heart tissue. EP studies are done to diagnose your cardiac rhythm abnormality especially in a patient with palpitation or unexplained loss of consciousness, to help determine the best treatment. EP study allows the Electrophysiologist to determine the specific location of an arrhythmia and, often, to correct it during the same procedure.
Patients are referred for EPS for many reasons.
Some of the more common reasons are:
In order for the heart to do its work (pumping blood throughout the body), it needs a sort of spark plug or electrical impulse to generate a heartbeat. Normally this electrical impulse begins in the upper right chamber of the heart (in the right atrium) in a place called the sino-atrial (SA) node. The SA node is the natural pacemaker of the heart. The SA node gives off electrical impulses to generate a heartbeat in the range of 60 to 100 times per minute.
In some hearts, an abnormal heart rhythm develops when an electrical impulse either starts from a different location, other than the SA node, or follows a route (or pathway) that is not normally present.
Your doctor will explain the exact nature of your abnormal heart rhythm and the following diagrams should help you understand the mechanism.
This is the most common form of SVT. An abnormal short circuit (circular conduction) occurs near the AV node. Instead of a single AV node between the top and bottom chambers, there is a second connection that is abnormal. This extra connection has been present since birth. As a result of having 2 connections a short-circuit can occur.
Abnormal circular conduction utilising the AV node and an “accessory pathway” connecting the atria and ventricles. This extra connection has been present since birth. As a result of having 2 connections a short-circuit can occur. This condition is sometimes termed the Wolff-Parkinson-White Syndrome or WPW.
This is the least common form of SVT. There is an extra abnormal origin of the electrical impulse from a small area in the atria other than the SA node. It is not known when or why such an extra focus develops.
In atrial flutter, abnormal electrical signals circulate in the heart’s upper chambers, or atria, which causes the rhythm of the lower chambers to be fast. Because contractions are not timed as in the normal heartbeat, the heart does not pump blood as effectively to the rest of the body. Irregular heartbeats can be seen on an electrocardiogram, or ECG
In atrial fibrillation, disorganized electrical signals originate in the heart’s upper chambers, or atria, causing the rhythm to be irregular. These signals come from small areas in the heart represented here by stars. Irregular heartbeats can be seen in an Electrocardiogram or “ECG”. Because contractions are not coordinated as in the normal heartbeat, the heart does not pump blood effectively to the rest of the body.
Ventricular Tachycardia is a heart arrhythmia, or irregular heartbeat. In ventricular tachycardia, abnormal electrical pulses in the lower chambers, or ventricles, disrupt the normal firing of the SA node, causing the heart to beat rapidly. These signals can be seen in an Electrocardiogram or ECG. A rapid heartbeat does not give the heart enough time to refill with blood before pumping, which causes diminished blood flow to the rest of the body. This may lead to symptoms of dizziness, lightheadedness, unconsciousness.
The EP study is a very low-risk procedure. The world wide complication rate for EP study is less than 0.5%.