(see also Electrophysiology Studies; Wolff-Parkinson-White Syndrome; MAZE Procedure)

Catheter-based ablation using radio-frequency, cryothermal, or sometimes laser energy can be used to treat the vast majority of arrhythmias. The procedure is based on results of an electrophysiology study and is used to eliminate accessory pathways in the electrical system of the heart. A specially designed catheter is positioned next to the extra pathway, and either radio-frequency energy (radio waves) or cryothermal energy (intense cold or laser energy (light waves) is delivered via the catheter. This creates scar tissue, which eliminates the pathway and consequently the unwanted rhythm. Additionally, there is a surgical approach to treatment via the MAZE procedure, which is discussed later in this text.

Catheter ablation continues to evolve based on a growing body of knowledge about atrial fibrillation mechanisms and with more advanced tools and techniques available for treatment. Currently, there are three newer technologies being researched that may offer alternative treatment options:

• The use of MRI to directly visualize catheters and the tissue reaction to ablations
• The use of fully robotic externally applied radiation therapy or focused ultrasound to ablate the pathway without the need to catheterize the patient
• Electroporation, where tailored electrical charges are used to open pores in the cell walls of the targeted tissue, resulting in cell death

The success of catheter-based ablation varies significantly depending on the arrhythmia being treated. Although paroxysmal supraventricular tachycardia has a 95% success rate after a single procedure, persistent atrial fibrillation is much lower at approximately 60%. Even when the extra pathway appears to have been successfully eliminated, the pathway function may return later, requiring a repeat procedure.

The ablation procedure takes place in the EP (electrophysiology) suite or a cardiac catheterization lab and is a minimally invasive procedure with a short recovery period. All procedures have risks, and while blood clots, strokes, or perforations of the pulmonary veins or heart are possibilities during ablation; the overall complication rate is very low.