What Is Catheter Ablation?
The aim of catheter ablation is to isolate areas of the heart that are causing rhythm disturbances from the rest of the heart. Catheter ablation, also known as radiofrequency ablation, is a procedure performed by an interventional cardiologist. It involves threading catheters – long flexible wires – through a blood vessel and into the heart. Special cells in the heart create electrical signals that travel along pathways to the heart chambers. These signals make the hearts upper and lower chambers beat in the proper sequence and rhythm. Abnormal or diseased tissue may create disorganized electrical signals causing rapid or irregular heartbeats called arrhythmias. (link to heart rhythm disorders) The cardiologist uses electrodes to deliver a safe pulse of radiofrequency energy to destroy these diseased areas of heart tissue, helping to restore the heart’s regular rhythm. People who can benefit from catheter ablation include those who:
- have arrhythmias that don’t respond to medication or suffer negative side effects from arrhythmia medication
- have a specific kind of arrhythmia which tends to respond well to catheter ablation
These specific types of arrhythmia, for example, include:
- atrial flutter
- AV nodal reentrant tachycardia (AVNRT): a very fast heartbeat caused by a short circuit in the heart
- accessory pathway: a fast heartbeat due to an abnormal electrical pathway connecting the heart’s upper and lower chambers
- atrial fibrillation: an irregular and fast heartbeat originating in the heart’s two upper chambers (link to heart rhythm disorders)
- ventricular tachycardia: a very fast and dangerous rhythm originating in the heart’s two lower chambers (link to heart rhythm disorders)
The interventional cardiologist performs the procedure along with a team of nurses and technicians.
Catheter ablations take place in a special room known as an electrophysiology laboratory, sometimes called a cath lab. Depending on the hospital and type of arrhythmia being treated, the procedure may take place under general or local anesthesia with sedation.
In cases of atrial fibrillation the affected cells are usually located in the left atrium around the lung veins. To reach the affected area the physician introduces a thin flexible tube into a large blood vessel in the groin and guides it carefully into the left atrium. There he destroys the “bad tissue” with either heat (radiofrequency energy) or extreme cold (cryoablation). The resulting scarification isolates the affected area from the healthy area of the heart. After the procedure, the patient receives anticoagulant medication to prevent the formation of blood clots. The heart’s activity will be measured regularly after the ablation procedure in order to assess whether it was successful; if necessary, it will be repeated.
At the start of the procedure the cardiologist will numb the puncture site with a local anesthetic. Then he or she will make a small needle puncture through the skin and into the blood vessel (typically a vein, but sometimes an artery) in the patient’s groin. A small straw-sized tube called an introducer sheath will be inserted into the blood vessel. The cardiologist will gently guide a catheter into the vessel through the sheath. A video screen displays the position of the catheter. Patients may feel some pressure in the groin, but shouldn’t feel any pain. The cardiologist then inserts several catheters, through the sheath and gently guides them into the correct position in your heart. To locate the abnormal tissue causing the arrhythmia, the cardiologist sends a small electrical impulse through the electrode catheter. This activates the abnormal tissue making it visible. Other catheters record the heart’s electrical signals to help locate the abnormal sites. The cardiologist places the catheter inside the heart, at the exact site where the abnormal cells are located. Then, a mild, painless radiofrequency energy is sent to the tissue. This destroys heart muscle cells responsible for the extra impulses in a very small area that had caused the rapid or irregular heartbeats.
Catheter ablation usually takes two to four hours. If there is more than one area of abnormal tissue, the procedure can take longer. Some people may still experience short episodes of irregular heartbeat after catheter ablation. This is a normal reaction as tissue heals, and should go away over time.
Risks include bleeding, pain, and infection at the catheter insertion site. More serious complications are rare, but may include:
- blood clots
- damage to the heart valves or arteries
- fluid build-up around the heart
- heart attack
- pericarditis, or inflammation of the sac surrounding the heart
An ablation involves a small degree of risk. The cardiologist will explain the potential risks to the patient before the procedure, and will only recommend this procedure if he or she thinks the benefits outweigh them.