This leaflet is designed to provide information about the investigation and treatment you may receive in the Electrophysiology laboratory. Please read it carefully. If you require more information or have any concerns or questions, please discuss these with your doctor prior to the procedure.
Your doctor has determined that you may have a heart rhythm disturbance and has recommended that you have an Electrophysiology (EP) study. The EP study looks at the conduction or electrical system of your heart by recording electrical activity from within the heart chambers. The study is designed to make a diagnosis and determine a course of treatment that will help control your arrhythmia and help protect you from future occurrences.
If the heart rhythm disturbance is caused by an extra pathway of electrical conduction within the hearts existing conduction system, your doctor may recommend that you have a radio- frequency ablation. An ablation is a procedure where the extra pathway is destroyed by radio- frequency energy. It is often performed as an extension of the EP study.
Risks and Possible complications
EP studies have been performed hundreds of thousands of times over the past 20 years and are considered routine for many arrhythmia patients. The test is always conducted by an experienced medical team using state-of-the-art equipment. We have a single-use only policy on our diagnostic and ablation catheters.
- Cardiac arrhythmia
- Mild pain during RF application
- Vascular complications
- Haematoma (bruise)
- Thrombosis (blood clot)
- Thromboembolic event (including stroke)
- Valvular damage
- Catheter perforation of atrium or ventricle
- Exposure to radiation
Major adverse events from these complications are rare (1:1,000 or less)
N.B in the event of ablation in the region of the AV node, normal conduction can be inadvertently damaged resulting in heart block. This may require a permanent pacemaker. This risk can be as high as 3%.
If you have any questions or concerns please raise them with the medical or nursing staff.
The Electrical System of the Heart
To pump oxygen-rich blood throughout the body, the heart needs an electrical impulse to generate a heartbeat. The electrical impulse starts in the heart's natural pacemaker called the sinus node. The sinus node is found in the top right chamber of the heart called the right atrium. The electrical impulse travels down from the sinus node to the other tissues of the conduction system. This causes the heart muscle to contract in an orderly sequence. The two atria squeeze a little earlier than the two ventricles. This causes the heart to pump.
The heart normally beats at 60-100 times a minute. This is called normal sinus rhythm. Sometimes the heart beats slower, (for example, when asleep), or faster, (when exercising). There are certain conditions where there is extra electrical activity outside the sinus node. This can cause the heart to beat very quickly (this is called tachycardia). If the tachycardia comes from the top chambers of the heart it is called supraventricular tachycardia (SVT), and if it comes from the lower chambers, it is called ventricular tachycardia (VT)
SVT may result from an extra electrical connection between the top and bottom chambers.
A diagram to show extra connections both within and outside the AV Node. (It is this connection that is targeted during ablation)
Symptoms of tachycardia may include-
- Dizziness or light-headedness
- Feeling tired
- Chest pain or feeling of tightness in the chest
- Episodes of fainting
- Shortness of breath
Similar symptoms can also occur if the heart beat is persistently, or intermittently, too slow (called bradycardia).
If your doctor prescribes a medicine for your heart rhythm disturbance after the study, it is important for him to make sure that this medicine is working correctly. Therefore, when your doctor determines that you have an effective blood level of medication, you may be brought back to the EP lab for a follow-up study. This is different from the first study in that there is usually only one catheter placed in the heart and the whole test is completed in approximately an hour.
If further medication adjustments are necessary to control your heart rhythm disturbances, you may come back to the EP lab more than once. "Taking it one day at a time" is the best way of dealing with your hospital stay.
What happens if medicines don't work for me?
Medicines may not be the answer for your type of heart rhythm disturbance; however, there are other ways of treating your problem.
Your doctor will discuss these alternatives with you.
Is it worth it?
The EP study is the most comprehensive method available for evaluating and treating your heart rhythm disturbance. We hope this testing will provide you with a safe and effective therapy that will keep you from coming back to the hospital.
After the EP study and Ablation
When the test is completed, you will be returned to your room on your bed. Since the catheter insertion areas require time to heal, it is in your best interest to follow these simple rules:
- Stay in bed, usually 3-6 hours. Your nurse will assist you to get up when the time is right.
- Keep your legs straight if the catheters were inserted in the groin. To sit up or to bend your knees may cause the site to bleed.
- Keep your head on the pillow.
- Inform the nurse if you have any warmth, pain or swelling in the area where the catheter was inserted.
The nurse will be reminding you of these rules. Your nurse will also make sure you have something to eat and drink, that you are comfortable, and that any questions or concerns you may have are answered. Your blood pressure, pulse and catheter insertion site will be checked frequently after your return to your room. You may have a heart monitor applied. It is not unusual to experience some bruising in your groin, which may last a few days. You may be asked to take aspirin for 3 months after your ablation procedure (to prevent tiny blood clots forming at the ablation sites). Depending on your job, you should be able to go back to work in a few days. You should avoid very heavy physical activity for 1-2 weeks. Arrangements for follow up will be made with your referring Physician.
You may experience some extra or missed heart beats in the days and weeks after an ablation- these are quite common and may last for a few months. However, if you experience persistent palpitations, please inform your doctor.
Preparing for the EP and Ablation Procedure
You may be asked to stop taking certain tablets before you come into hospital for the ablation. This is to obtain the most accurate results. An electrocardiogram (ECG) will be taken on the ward. It is possible that a blood test and a chest x-ray are also needed.
You will be seen by a doctor before the EP study and ablation, who will explain what the procedure involves and any risks or complications associated with the procedure. This is a good time to ask any questions or explain any worries that you may have. When you feel that you have a good understanding of the procedure, the doctor will ask you to sign a consent form.
It is important to have an empty stomach prior to the procedure, therefore you will be asked to have nothing to eat or drink for at least four hours beforehand. A small sip of water before the procedure with any other tablets you are talking is alright. If you wear dentures these can remain in place providing that are well fitting.
The cardiology attendant will transport you to the Electrophysiology laboratory where the procedure takes place.
The EP Study and Ablation Procedure
Your ward nurse will go with you and introduce you to the Catheter laboratory staff. You will be taken to the room where the study will take place. There will also be a doctor, technologists, nurses and a radiographer present. Once you are lying on the bed the technologists will explain the procedure and equipment in the room and place ECG electrodes on your chest, RF dispersion patches on your back, and an oxygen saturation monitor on your finger, so that you can be monitored and observed throughout the study. You may, or may not, also be attended by an Anaesthetist.
A small cannula (like needle) will be inserted into a vein in your arm so that drugs can be easily given during the study (IV). It is not unusual to feel a little tense or anxious, and therefore, a sedative may be given into the cannula in your arm. Your right groin will be cleaned with iodine anaesthetic solution and local anaesthetic injected into these areas. The local anaesthetic will cause a stinging sensation for a few seconds and then the area will feel numb.
The wires required to record electrical signals from within the heart will then be inserted through fine plastic tubes in your groin. This should not cause you any pain, but if there is some discomfort, please let the doctor or nurse know. The wires are positioned using x-ray equipment that lies above your chest. As with all x-rays, if there is any chance that you are pregnant, please let the doctor or nurse know before the procedure begins. The staff in the room will wear protective lead aprons. This is because they are exposed to x-rays everyday, however the dose of x-rays that you receive is small and protective clothing is not necessary.
Once the wires are positioned the doctor will look at your heart rhythm disturbance by recording the electrical signals on a computer. A special machine (an artificial pacemaker) is used to give the heart small electrical impulses to make the heart beat at different rates. You may be aware of your heart racing or missing beats, but it is the doctor and technologist doing this and you should not be worried. However, if you feel uncomfortable, please let the doctor or nurse know how you feel. They may ask you if you feel light-headed, faint or short of breath. It is usually possible to stop fast rhythm with the artificial pacemaker, which can be done quickly if you feel unwell.
In some cases, the rapid heart rhythm disturbances may be continued. You may actually pass out, but this will be for an extremely short period of time. A small electric shock may be required to restore your normal rhythm. Although it may be frightening to think about these aspects of the procedure, most patients do not report experiencing any pain. Some people do not even realise that they have passed out.
Not everyone passes out, but there is no way of predicting if this will happen. If it does happen, when you first wake up you may not know where you are or what happened. Be assured, staff will be right at your side to comfort and reassure you.
At this time, your doctor may prescribe a medication to control your irregular rhythm. This drug will be given through your IV. During this time your blood pressure will be checked. Once an adequate amount of drug has been given, the doctor will then check to see how effective it is for you.
If the cause of your palpitations are due to an extra electrical pathway or connection, your doctor will identify the exact location of extra electrical activity and radio-frequency energy will be applied using a special machine. This usually does not cause pain. It is often necessary to deliver several amounts of energy to ensure complete destruction of the extra pathway, and there is usually a waiting time of up to half an hour to ensure that the procedure has been successful.
When the EP study has been completed, which usually takes 2-4 hours, the doctor will remove the catheters. To prevent bleeding, pressure will be applied to the catheter insertion site for 5-10 minutes. A small sterile dressing will be applied which can be removed later. No stitches are required. The results of the test may be discussed with you in the lab or after you have returned to your room. Don't be afraid to ask questions.