Catheter Ablation

Catheter ablation refers to the destruction of small parts of arrhythmia circuits using a specially designed wire, or catheter, to search out the circuit and deliver a small burn in the heart to a part of the circuit. This technique is a common treatment for SVT and is performed during an electrophysiology study. A catheter-a long, thin, plastic-coated wire with several metal contacts on it-is guided to the location of the circuit after the physician has determined what type of arrhythmia is present. This process of "mapping" the circuit is done using X-ray images of the heart to direct the catheter and by analyzing electrical signals from the heart collected by the catheter to find the circuit. Once the circuit is mapped, electrical energy is delivered to the tip of the catheter, where it is converted to heat. The heat causes a small burn at the site of the catheter tip. The burn destroys part of the arrhythmia circuit so that it can no longer be activated.

The most common side effects associated with catheter ablation are those encountered with any IV insertion, including bleeding at the site when the catheter is removed, infection, blood clot formation within the vessel, and bleeding under the skin with formation of a hematoma.

The catheters are stiff wires that can actually pierce the wall of the blood vessels if handled roughly, but when the catheters are handled carefully vessel damage seldom occurs. Perforation of the wall of the heart can also occur. Perforations of the heart wall by pacemaker catheters that have been in place for a long time has been observed frequently during heart surgery for other problems, and usually these perforations cause no symptoms or problems. Problems occur when bleeding into the space in which the heart sits causes the heart not to be able to fill normally due to lack of space; this condition is called pericardial tamponade. When pericardial tamponade occurs, drainage of the blood from the space corrects the problem. Drainage can usually be done with a needle.

Just as damage to the arrhythmia circuit is the desired result of the ablation procedure, the other main complication observed during ablation procedures is damage to the normal conduction system of the heart. Most of the arrhythmia circuits targeted for ablation actually lie some distance from the normal conduction system, but not all do. The risk of damage to the conduction system should be discussed with the physician before the procedure since it differs depending upon where the arrhythmia circuit is thought to be. Sudden movement by the patient during the ablation can cause the ablation catheter to move and damage the normal conduction system. If the damage is severe, a permanent pacemaker may be necessary.