|  Find a Doctor   |  Getting to NUHCS   | Appointment   | Contact Us   | Newsroom  |  Make a Gift  | About NUHS  | Protecting Your Data

Home > Our Services > Conditions and Treatments > Electrophysiological Study (EPS)

Electrophysiological Study (EPS)






An electrophysiological study (EPS) is a highly specialised cardiac procedure performed when your doctor suspects that you have abnormal heart rhythms and/or conduction disorders. It may be used to evaluate patients' symptoms of palpitations, unexplained fainting and potentially life-threatening heart rhythms that may cause sudden cardiac death. Some of these heart rhythm abnormalities may be amenable to cure using radiofrequency catheter ablation. The arrhythmia service also encompasses the implantation of pacemakers for electrical conduction disorders, cardiac resynchronization therapy for heart failure and defibrillators for patients with lethal arrhythmias.


A cardiac electrophysiology study (EPS) helps the cardiologist to identify your rhythm disturbance, the cause of this disturbance, and choose the best method of treatment.


During the EPS, the electrical behavior of the heart that is responsible for controlling your heartbeat is recorded by placing conducting wires (or leads) positioned at strategic locations within your heart. Through these leads, the electrical conduction of the heart can be studied, and any abnormal conduction can be identified.


Back to Top



What is the purpose of this test?


The EPS is used to study the electrical conduction system of the heart, and to detect abnormal conduction that may be responsible for the heart rhythm disturbances that produce your symptoms. It is also useful in monitoring how effective medications are in controlling abnormal heart rhythms.


Heart rhythm abnormalities are often the result of electrical "short circuits" in the heart. These may be treated using radiofrequency energy (much like your microwave) to eliminate (ablate) areas of abnormal conduction


Back to Top



What to expect?


The goals and risks of the procedure will be discussed with you by your doctor. A 2-3 days hospital stay will be needed, and on the day before the test, you will need to be admitted.


Upon admittance, the following will be carried out:


  • Preparatory blood tests
  • An electrocardiogram (ECG)
  • To sign a consent form before the EPS - If you're a woman of childbearing age, you may be required to take a urine pregnancy test.
  • A small needle (herapin plus) will be inserted into one of the veins on your hand to facilitate injections of medication during the test, if necessary.
  • From midnight on the day of the test until after the procedure is completed, you will not be allowed to consume food nor drinks.
  • Just before the test, your groins and chest may be shaved.


The EPS is performed in the Invasive Cardiac Laboratory by the cardiac electrophysiologist (a trained specialist who performs this test) and may take about 1 to 2 hours, sometimes longer for complex cases.


  • Medication to help relaxation or sleep will be given through the heparin plug
  • You need to lie fairly still throughout the study
  • Several leads will be inserted through your groin, as well as the neck or arm after injection of local anaesthetic.
  • Using X-ray to guide the wires positioning, the leads are advanced into the heart
  • When the leads are placed at the desired locations in the heart, the electrophysiolgist will:
        • Record the electrical activities of your heart
        • Stimulate your heart with mild electrical current to observe the response


You may experience palpitations (a sensation of the heartbeat) during the test. However, if you experience any discomfort during the procedure, please inform the electrophysiologist.


When the examination is completed, the leads will be removed and the tiny wounds at the puncture sites will be compressed for a few minutes to stop any bleeding. The wounds should heal within a few days.


After the test, you will need to lie in bed for about 4-8 hours and avoid moving the limbs which the leads had been inserted in to aid the healing of the blood vessels and avoid bleeding. If you feel pain or swelling in the area, you must inform the nurse, and if necessary, painkillers will be prescribed. You will be able to go home the next day.


 Back to Top



What to prepare?


  • You may be advised to stop taking certain medications before your EPS.
  • Should you have any allergy, especially allergies to X-ray contrast, any heart rhythm medications and pain-relieving medication, please inform your doctors.

 Back to Top


After being discharge


  • You should be able to resume most of your usual activities the day after your discharge, however, should the need arise, medical leave may be issued to allow you to rest at home
  • Cover the punctured wounds with waterproof plasters for 2 days, after which, the plaster can be removed. Thereafter, the wounds can be left exposed or covered with a Handiplast.


Back to Top



What are the potential risks or complications?


The EPS is an extremely safe procedure. Most complications are minor - pain, swelling, bruising and bleeding from the puncture sites. Occasionally, the procedure may induce the occurrence of abnormal heart rhythm that may require an electric shock to terminate. Very rarely, major complications such as infection and damage to the blood vessels may occur, but these complications can usually be treated without residual injury. Pregnant women should not undergo this test due to the exposure to X-ray radiation.


 Back to Top



When will you get the results?


The electrophysiologist will usually inform you of the results of the study during the procedure, or some time later. He/She will also discuss with you about the treatment options, if necessary.



Back to Top