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Author: Leonard I Ganz, MD
Editors: Brian Olshansky, MD; Leah K Moynihan, RNC, MSN; Susan B Yeon, MD, JD, FACC
RADIOFREQUENCY CATHETER ABLATION OVERVIEW — Radiofrequency catheter ablation is a procedure that is performed to correct a disturbance in heart rhythm. A brief review of how a normal heart rhythm occurs and a description of some of the rhythm problems that are treated with this procedure will help in the understanding of radiofrequency catheter ablation.
How does the heart normally work? — Heart muscle cells are stimulated by electrical impulses that cause them to contract in a uniform way and with a regular rate. This contraction produces the heartbeat, which causes blood to be pumped out of the heart into arteries and then to all parts of the body. The flow of blood into arteries can be measured by feeling the pulse, which corresponds to the heartbeat.
In the normal heart, electrical impulses arise from an area of specialized cells called the sinus node, which is the heart's normal pacemaker. The sinus node is located in the right atrium, the upper right chamber of the heart (figure 1). After leaving the sinus node, an impulse spreads across the upper heart chambers (right and left atria) and reaches the atrioventricular (AV) node located near the center of the heart between the atria and the lower chambers, or ventricles, and then to conduction fibers that spread across the ventricles, which are the heart's main pumping chambers. As the impulse moves along the conduction fibers, cardiac muscle cells are stimulated and contract, producing a heartbeat (figure 2).
Sometimes, the electrical impulses "short circuit" the normal pathway and travel across the heart in an abnormal way. Abnormal pathways, or routes, for the impulses can develop, causing irregularities in the heartbeat, or arrhythmias. In other cases, arrhythmias arise when areas other than the sinus node become active and begin to send out impulses that either compete with or take over the pacemaker function of the sinus node. Typically, the result of these abnormalities is a heartbeat that is too fast. This is known as tachycardia, and it may develop in any location within the atria, AV node, or ventricles.
 WHAT IS RADIOFREQUENCY CATHETER ABLATION? — Radiofrequency ablation is a procedure that can cure many types of fast heart beats (called tachycardia). Using small tubes or catheters that are threaded into the heart, radiofrequency energy (low-voltage, high frequency electricity) is targeted toward the area(s) causing the abnormal heart rhythm, permanently damaging small areas of tissue with heat. In some cases, cryoablation, which damages tissue by freezing rather than heating, may be used rather than radiofrequency energy.
The damaged tissue is no longer capable of generating or conducting electrical impulses. If the procedure is successful, this prevents the arrhythmia from being generated, curing the patient.
A pacemaker is a small electrical device that stays in the body and is connected to the heart with wires that stimulate the heart to contract in a regular way. In some patients, insertion of a pacemaker is a planned part of the procedure. In other cases, the need for a pacemaker is a complication of the ablation procedure. A doctor can tell whether a patient will need a pacemaker after the ablation. (See "Patient information: Pacemakers".)
WHICH RHYTHM PROBLEMS CAN BE TREATED? — Radiofrequency ablation can be used to treat many arrhythmias that cause a fast heartbeat (table 1).
Radiofrequency ablation may be recommended for:
* Paroxysmal supraventricular tachycardia (PSVT), which includes:
* - Wolff-Parkinson-White syndrome (see "Patient information: Wolff-Parkinson-White syndrome")
* - AV nodal reentrant tachycardia
* - Atrial tachycardia
* Atrial flutter
* Ventricular tachycardia and premature ventricular contractions (see "Patient information: Palpitations and extra heartbeats")
* Atrial fibrillation (see "Patient information: Atrial fibrillation")
 RADIOFREQUENCY CATHETER ABLATION
Preparation — Patients may be asked to discontinue certain medications in the days before the procedure. Most patients are advised to stop eating and drinking at midnight the night before the procedure.
Some physicians suggest that premenopausal women avoid ablation during their menstrual period because blood thinning medications may be used, which could cause excessive menstrual bleeding.
Procedure — Before the procedure begins, you will be given a sedative medication through an intravenous (IV) line; most patients are not aware of what is happening during the procedure.
Small catheters will be threaded into the heart. The catheters are usually inserted into the vein or artery in the right and left groin (inner thigh) and are then positioned within the chambers of the heart using fluoroscopy (low energy x-rays). Occasionally, catheters are inserted via veins into the side of the neck, upper chest, or arm. The doctor will test various parts of the heart and usually will try to provoke the arrhythmia.
The sections of the heart that are causing your arrhythmia can be identified. The doctor will then use the radiofrequency energy (or cryoablation) to treat the problem area. During the procedure, your heart rate and rhythm, oxygen level, and blood pressure will be monitored.
When the procedure is completed, the doctor will again try to provoke the arrhythmia. If it cannot be induced, the procedure is considered to be a success. However, if the arrhythmia can still be induced, additional radiofrequency energy is delivered.
The length of the procedure varies from patient to patient, depending upon the type of arrhythmia being treated and other factors. Typically, the procedure lasts two hours or more.
Post-ablation care — You will be taken to a recovery area while the effects of the sedative medication wear off. The catheter site will be monitored for bleeding and the heart rhythm is observed closely during this period. You must stay in bed for several hours to reduce the risk of bleeding from the catheter site. You usually feel tired but well. Pain medication is usually needed for only a short time, if at all.
Some patients are admitted to the hospital after the procedure while others go home later the same day. Certain activities are not recommended for a brief period to avoid straining the catheter site.
You may be asked to take aspirin every day for several weeks after the procedure to prevent blood clots. The doctor will give more detailed information about medications needed after the procedure.
RADIOFREQUENCY ABLATION COMPLICATIONS — Like any invasive procedure, radiofrequency ablation carries some risk. However, the risk of these complications is small in most cases.
Possible complications include:
* Problems related to threading the catheters through the blood vessels such as bleeding, infection, blood clots, bruising, and injury to the vessel(s)
* Injury to the heart as a result of the catheters; this includes a perforation through the muscle or damage to one of the valves within the heart
* Blood clots that travel to the lungs (pulmonary embolism) or brain (stroke)
* Heart block, or failure of any electrical impulse to travel from the top parts of the heart to the bottom. This complication, if permanent, requires implantation of a pacemaker.
* New arrhythmias
* Exposure to radiation during the procedure, which can take several hours. This can produce a very small increase in the risk of cancer or genetic defects.
* Death (occurs in approximately 0.1 to 0.3 percent of cases)
OTHER ARRHYTHMIA TREATMENTS — Other arrhythmia treatments may be available, depending in part on what type of arrhythmia is present. Medication, pacemakers, cardioversion (delivering an electrical current to the chest to restore a normal rhythm), and surgery are examples of treatments that may be used for particular arrhythmias. (See "Patient information: Pacemakers" and "Patient information: Cardioversion".)
Some types of arrhythmias are temporary and non-life threatening; patients can be taught certain maneuvers (such as coughing or increasing pressure in the abdomen) that may stop the arrhythmia. Detailed information about available alternative therapies is available from a healthcare provider.
Reference:
http://www.uptodate.com/patients |
