EPS evaluates the electrical conduction system of the heart, which controls the rate and timing of the heart's contractions. A catheter with an electrode tip is inserted into a vein in the groin (or arm, in some cases) and threaded to the heart, using a special type of x-ray, called fluoroscopy, to guide the catheter. The electrode records the heart's electrical activity, and is then used to send pacing signals to the heart in an attempt to produce abnormal heart rhythms (arrhythmias) and thus pinpoint their origin. EPS is sometimes combined with a treatment called radiofrequency ablation, in which radiofrequency energy is used to obliterate small areas of the heart that induce arrhythmias.
Purpose of the EPS
- To localize the source of cardiac arrhythmias and other defects in the heart's electrical system
- To assess the effectiveness of various antiarrhythmic drugs or monitor antiarrhythmic drug therapy
- To evaluate the potential effectiveness of a pacemaker or automatic implantable cardioverter-defibrillator (another type of implanted pacing device)
- To assess symptoms of a heart rhythm problem, such as dizziness, fainting, weakness, palpitation, or other symptoms when other noninvasive tests have been inconclusive
Who Performs EPS
- A cardiologist specializing in EPS, assisted by specially trained nurses and technicians
Special Concerns about EPS
- Because EPS may induce arrhythmias, this test must take place under carefully controlled conditions in a cardiac catheterization laboratory.
- People with severe bleeding disorders or a recent blood clot in the lungs or extremities are not candidates for this procedure.
- Certain medications, including painkillers, sedatives, and tranquilizers, may interfere with test results. Inform your doctor of any medications you are taking.
Before the EPS
- Do not eat or drink anything for 6 to 8 hours before the test.
- Empty your bladder right before the test.
- Tell your doctor if you have any known allergies or sensitivities to medications, iodine, latex, tape, or anesthetic agents (local and general).
- Tell your doctor if you are pregnant or may be pregnant.
- Inform your doctor if you have any body piercing on your chest and/or abdomen.
- Tell your doctor about all medications (prescription and over-the-counter), herbal supplements, and dietary supplements that you are taking.
- Inform your doctor if you have heart valve disease, as you may need to receive and antibiotic prior to the procedure, or if you have a pacemaker.
- Tell your doctor if you have a history of bleeding disorders or are taking blood-thinning (anticoagulant) medications, aspirin, or other medications that affect blood clotting. In some cases, these medications must be discontinued prior to the procedure.
What You Experience during EPS
- An intravenous (IV) line is inserted into a vein in your arm to allow administration of medications during the test.
- You lie on your back on a table, and ECG leads are applied to monitor your heart rate and rhythm.
- The skin at the site of catheter insertion (usually the groin, but occasionally the arm or neck) is shaved and then swabbed with an antiseptic, and a local anesthetic is administered to numb the area. The doctor then makes a small incision and inserts a catheter into the vein; you will feel pressure during insertion, but no other discomfort.
- The doctor threads the catheter to your heart using continuous x-ray imaging, or fluoroscopy, to watch its progress on a viewing monitor.
- Once the catheter has been guided to your heart, recordings are made of your heart’s electrical activity, and various parts of the electrical conduction system are stimulated with pacing signals. This process may induce arrhythmias, causing you to experience lightheadedness, dizziness, or palpitations.
- Your vital signs are monitored throughout the procedure, and the medical staff may continually engage you in light conversation to ensure you are stable and conscious. Report to them any symptoms you experience due to arrhythmias.
- Different antiarrhythmic drugs may be injected into your IV line to evaluate how well they stop the abnormal rhythms, and to select the best medication for you.
- If the doctor decides that radiofrequency ablation is appropriate, it will be performed directly after EPS is completed.
- Simple EPS generally lasts from 20 minutes to 1 hour. It may take longer if other procedures are involved.
Risks and Complications of EPS
- Serious complications of EPS include induced arrhythmias leading to ventricular tachycardia or fibrillation (life-threatening arrhythmias that can cause cardiac arrest and death); perforation of the heart muscle; stroke or heart attack due to a catheter-induced blood clot; peripheral vascular problems; hemorrhage; and inflammation of the vein (phlebitis) at the site of catheter insertion.
- When performed by experts, the risk associated with EPS is very low, but emergency equipment is available if serious complications arise.
After the EPS
- After the procedure is completed, you must remain in a hospital bed for a few hours, with pressure placed on the site of catheter insertion to prevent bleeding.
- Your blood pressure and other vital signs will be monitored periodically during this time, and the catheter insertion site will be checked for signs of bleeding. Tell your nurse immediately if you experience chest pain or tightness; other pain; or warmth, bleeding or pain at the insertion site in your leg or arm.
- If radiofrequency ablation was performed during this procedure, you must remain in the hospital overnight.
- You may resume your normal diet and any medications withheld before the test.
Results of EPS
- Depending on the results of this test, your doctor will recommend an appropriate treatment, such as antiarrhythmic medication, a pacemaker, or an automatic implantable cardioverter-defibrillator.
- If radiofrequency ablation was performed, it may be a definitive treatment for your cardiac arrhythmia.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media