Electrophysiology (EP) Study and Endocardial Catheter Ablation
What is an EP Study?:
An electrophysiology (EP) study is a method for assessing the heart’s electrical function. During the study a specialized physician, called a cardiac electrophysiologist, inserts electrode catheters (long and flexible wires) into the veins and guides them into the heart. This is performed on a special sterilized room and is performed under sedation or general anesthesia. The catheters are inserted through the groin and shoulder veins under local anesthesia (numbing medicine). Once inside the heart, this catheter can sense electrical impulses in various areas. The catheters can also be used to stimulate different parts of the heart.
Different sides of electrical activity (inside the heart) are recorded on a special electrocardiogram paper.
The EP study protocol to be used depends on the type of arrhythmia of the patient. The timing of the electrical impulses will help determine if there is abnormal electrical conduction inside the heart. Multiple recordings of the electrical conduction intervals will help the electrophysiologist in analyzing what type of arrhythmia is present.
Cardiac mapping is performed in patients who have tachycardia (fast heartbeats) such as SVT (supraventricular tachycardia) and atrial and ventricular tachycardia. The electrophysiologist is able to sort out the exact site in which the arrhythmia is originating. Most patients have intermittent tachycardia; therefore, the arrhythmia must be induced (brought on) in the cath laboratory. In other words, the heart is stimulated at different intervals in order to reproduce the clinical arrhythmia.
An EP study may help in risk stratification. For example, patients with Wolff-Parkinson-White syndrome may develop tachycardia. A small percentage of these patients may be considered high-risk patients. The EP study will help determine if that is the case to proceed with endocardial catheter ablation.
Endocardial Catheter Ablation:
The EP study and catheter ablation are very similar procedures. In fact, the electrophysiologist usually decides to do both procedures, one right after the other, while you are in the EP laboratory.
Catheter ablation is a non-surgical technique that uses radio frequency energy or cryoablation catheters to get rid of the abnormal electrical pathway that is causing your heart to beat faster. The exact location of the abnormal electrical pathway is determined during the EP study by doing cardiac mapping. After that, a special ablation catheter is positioned at the site of the abnormal electrical pathway. In case of radio frequency energy, the tip of the catheter heats up and disrupts the small area of heart tissue that contains the abnormal electrical pathway. In the case of the cryoablation, the tip of the catheter cools down and disrupts the area of heart tissue with the abnormal pathway.
Cryoablation is a newer technique and is often used in patients with certain types of tachycardia such as AV node reentry tachycardia or accessory electrical pathways that are closed to the normal electrical conduction system.
After The EP Study And/Or Catheter Ablation:
After the study is completed and the catheters are removed, a nurse will apply firm pressure over the groin area for several minutes. This is done to prevent excessive bleeding. Special instructions will be given by the laboratory personnel and doctor regarding lying flat in bed for a few hours, not moving too much, and when you will be allowed to eat again.
Is the EP Study Safe?:
An EP study is a non-surgical but “invasive” procedure that requires insertion of catheters into your heart. It, therefore, does involve some risk. The risk is small and the procedure is considered relatively safe. Some patients may develop bleeding or bruising. The study may be associated with more serious complications. This includes heart block, damage, or perforation to the heart, formation of blood clots, and/or infection. Death is very rare. You should request a detailed explanation of the procedure and potential risks from the cardiac electrophysiologist who is to perform the EP study.