In some hearts, an abnormal heart rhythm develops in the top part of the heart 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. When this occurs, the heart will suddenly start racing. Often these episodes can occur at any time without a trigger.
Supraventricular Tachycardia can be treated with medication and through Radiofrequency Ablation.
The heart is a pump responsible for maintaining the blood supply to the body. It has four chambers. The two upper chambers (the right atrium and the left atrium) are the chambers that receive blood as it returns from the body via the veins. The lower chambers (the right and left ventricles) are the chambers responsible for pumping blood out to the body via the arteries.
In order for the heart to do its work (pumping blood throughout the body), it needs an 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. It provides the electrical spark that drives the heart to beat approximately 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. Certain medications may also slow the heart rate. All of this is appropriate.
From the SA node, the electrical impulse travels along the heart’s conduction system (the electrical wiring of the heart). The impulse spreads over the right atrium and 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 in the top part of the heart 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. When this occurs, the heart will suddenly start racing. The heart rate is usually over 150 beats per minute and often over 200 beats per minute. Certain things in some people can trigger episodes. These include caffeine, alcohol, anxiety, exercise or sudden movements such as bending over. However, often these episodes can occur at any time without a trigger. During an episode, you will usually be aware of the rapid beating of your heart. Other symptoms might include dizziness (blacking out may occur but is unusual), shortness of breath, sweating, chest pain and anxiety. After an episode, it is usual to feel very tired.
In the vast majority of cases, SVT is a benign condition. This means that it will not cause sudden death, damage the heart or cause a heart attack. It will not shorten life expectancy. There are some rare expectations that will be discussed with you if relevant.
There are 3 main types of SVT. It will not always be obvious which type of SVT you have prior to the electrical study of your heart.
There are 3 main options for people with SVT:
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 (or cauterising) a small area of abnormal tissue. Radiofrequency energy has been used for decades by surgeons to cut tissue or to stop bleeding. For the treatment of palpitations, much lower power of radio-frequency energy is used.
You will need to stop taking any medication that you have been prescribed for your abnormal heart rhythm approximately 5 days prior to your procedure, however, this will be confirmed by your cardiologist, and the nurse will call you one week prior to your procedure. If you are taking anti-coagulation (blood thinning) medications (e.g. Warfarin, Xarelto), then you will need to stop this 24 hours prior to your procedure, unless otherwise advised by your cardiologist. If this has not been discussed with you or if you are unsure, please phone the Rhythm and Cardiac Specialists to confirm.
You will usually be admitted to the hospital on the day of your procedure. You will be required to fast for at least six hours before the study. Prior to the procedure, you will require an electrocardiogram?(ECG). Once in the Electrophysiology Laboratory (EP Lab), 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. 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 that 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 will be washed with an antiseptic cleansing liquid and you will be covered with sterile sheets leaving these areas exposed.
The procedure is generally performed under local anaesthesia with sedation, or occasionally under general anaesthesia. This will be discussed with you prior to the procedure. If the procedure is performed under local anaesthetic, the doctor will inject the anaesthetic into the area in the groin where the catheters are to be placed. After that, you may feel pressure as the doctor inserts the catheters but you should not feel pain. If there is any discomfort, you should tell the nursing staff so that more local anaesthetic and sedative medication can be administered. Occasionally it is also necessary to place a catheter in a vein on the side of the neck.
The catheters are positioned in your heart using X-Ray guidance. Once the catheters are in place you may feel your heart being stimulated and usually, your abnormal heart rhythm will be induced. When the type of abnormal rhythm has been identified and the abnormal tissue is localised, the radiofrequency ablation will be applied to this spot. This may cause a transient warm discomfort in the chest. Radiofrequency ablation procedures are lengthy and the average duration is approximately 2 to 3 hours.
The success rate of the procedure depends on which type of SVT is present but is usually approximately 95% to 98%. The risk of tachycardia returning or recurring after an apparently successful procedure is approximately 5%.
After your procedure you will be transferred back to your ward where you will have to lie flat for 4 to 6 hours. During this time, it is important to keep your legs straight and your head relaxed on the pillow. Most patients stay in hospital overnight and their heart rhythm will be monitored during this time. The groin area may feel sore and bruised for several weeks after the procedure. You should avoid strenuous physical activity and sports for 2 weeks after the procedure until this has settled. Most people take approximately one week off work. Some people may experience minor chest discomfort and brief palpitations due to extra beats of the heart several days after the procedure. This is due to the irritation caused by the ablation in the heart and will settle. If this persists or is not mild, it should be reported to the Rhythm and Cardiac Specialists immediately.
Radiofrequency ablation procedures are performed on a daily basis. It is a common and very low-risk procedure. However, should a complication arise, it will be dealt with at once. The worldwide complication rate for radiofrequency ablation procedures is less than 0.5%. Although most people undergoing radiofrequency ablation do not experience any complications, you should be aware of the following risks:
Radiofrequency ablation is an effective and safe way to cure patients suffering from Supra-Ventricular Tachycardia.
