An Electrophysiology (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.
Patients are referred for EPS for many reasons.
Some of the more common reasons are:
The heart is a pump responsible for maintaining blood supply to the body. It has four chambers. The two upper chambers (the right atrium and left atrium) are the chambers which receive blood as it returns from the body via the veins. The lower chambers (the right and left ventricle) are the chambers responsible for pumping the blood out to the body via the arteries. Like any pump, the heart has an electrical system that controls how it functions.
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. If you are exercising, doing strenuous work or you are under a lot of stress, your heart rate may be faster. When you rest or sleep your heart rate will slow down. If you take certain medications, your heart rate may be slower. All of this is appropriate.
From the SA node, the electrical impulse is relayed along the heart’s conduction system. It spreads throughout both the right and left atria causing them to contract evenly.
When the impulse spreads over the right atrium it reaches the atrio-ventricular (AV) node.This is a very important structure in the heart because it is the only electrical connection between the top chambers and the bottom chambers. It is therefore the only way in which an electrical impulse can reach the pumping chambers (the ventricles). The impulse spreads through the AV node and down into the lower chambers or ventricles of the heart. This causes them to contract and pump blood to the lungs and body.
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.
These include;
You will be required to stop any medication you are taking for your abnormal heart rhythm 5 days prior to your procedure. If you are taking anti-coagulation (blood thinning) medication, such as warfarin or Xarelto then you will be required to stop these 24 hrs prior to your procedure. If this hasn’t been discussed with you, please call the Rhythm and Cardiac Specialists for further information.
The hospital will call you the day before your procedure to notify you of your admission and fasting times. The clinic’s nurse will call you one prior to discuss your medications and answer any questions you may have leading up to your procedure.
You will be required to fast for at least six hours before the study. If your procedure is in the afternoon, you may have a light breakfast.
You will be transferred to the Electrophysiology Laboratory (EP lab) from your ward. Usually before leaving your ward you will be given a light sedative and your groin will be shaved.
The EP lab has a patient table, X-Ray tube, ECG monitors and various equipment. The staff in the lab will all be dressed in hospital theatre clothes and during the procedure will be wearing hats and masks.
Many ECG monitoring electrodes will be attached to your chest area and patches to your chest and back. These patches may momentarily feel cool on your skin.
A nurse or doctor will insert an intravenous line usually into the back of your hand. This is needed as a reliable way to give you medications during the study without further injections. You will also be given further sedation if and as required. You will also have a blood-pressure cuff attached to your arm, which will automatically inflate at various times throughout the procedure.
The oxygen level of your blood will also be measured during the EP study and a small plastic device will be fitted on your finger for this purpose. Your groin area and possibly your neck or arm will be washed with an antiseptic cleansing liquid, and you will be covered with sterile sheets leaving these areas exposed.
The doctor will inject local anaesthetic to the area where the catheters are to be placed. After that, you may feel pressure as the doctor inserts the catheters but let the staff know if there is any discomfort so some more local can be given. Once the catheters are in place you may feel your heart being paced and possibly your abnormal heart rhythm will be induced.
After the procedure you will wake up in a hospital ward called the recovery area. When you are completely awake you will be transferred to the coronary care unit. You will have to lie flat for approximately 4 – 6 hours after the procedure. During this time, it is important to keep your legs straight and your head relaxed on the pillow. You will need to stay in hospital overnight after the procedure and your heart rhythm will be monitored. You will be reviewed by your Cardiologist before discharge the next day.
Radiofrequency is a low power, high frequency energy that causes a tiny region of the heart near the tip of the catheter to increase in temperature, thus ablating a small area of tissue.
Radiofrequency energy has been used for decades by surgeons to cut tissue or to stop bleeding. For the treatment of palpitations, a much lower power of radio-frequency is used.
Depending on the findings at your EP study it may be possible to ablate the mechanism for your abnormal heart rhythm. This is usually done at the same time as your EP study as the necessary electrodes within the heart are already in place.
Before the advent of radio-frequency ablation patients had two options to control their palpitations.
One is life-long medication, which works well in some patients, but requires the patient to take daily medication. There is also the possibility of side-effects from these drugs.
The other way of controlling the problem was by open-heart surgery to cut the accessory pathway. This was a very successful technique, and many patients were cured of their palpitations in this way. Besides the small risk of open-heart surgery and operation leaves a permanent scar on the chest.
The EP study is a very low-risk procedure and should a complication arise, it will be dealt with at once. The worldwide complication rate for EP/RF studies is less than 0.5%.
Although most people undergoing EP/RF studies do not experience any complications, you should be aware of the following risks:
Radio-frequency is an effective and safe way to cure patients suffering from palpitations.
Please do not hesitate to discuss any aspect of the procedure including potential complications with your doctor prior to your procedure.
