Catheter Ablation Techniques
Catheter ablation techniques are constantly evolving. Initial catheter ablations attempted to recreate the lesion set used in the Cox-Maze surgical procedure by employing linear ablation lines that interrupted the atrial fibrillation wavelets. The procedure had high complication rates and required long fluoroscopy times, so electrophysiologists moved on to focus more on the pulmonary vein area.1
Michel Haissaguerre, MD, and his colleagues created an early type of catheter ablation, called Segmental Pulmonary Vein Isolation. It ablates the pulmonary vein ostium, the opening to the pulmonary veins, by using radiofrequency energy that is applied to a portion of the pulmonary vein circumference, generally 30% to 80%.1
Subsequently, Carlo Pappone, MD, and his colleagues developed an alternative approach, called Circumferential Ablation. The HRS Consensus Statement indicates that this is the most common technique in use. It encircles the base (ostia) of the left and right pulmonary veins to electrically isolate them with guidance by a 3-D electronanatomical mapping system.1
The HRS Consensus Statement says that it is imperative to avoid ablating within the pulmonary veins in order to avoid pulmonary stenosis.1 The second worldwide study shows greatly decreased incidence of pulmonary vein stenosis.
Some centers, such as Johns Hopkins, use a hybrid approach that combines circumferential ablation and segmental PV isolation. They initially use circumferential lesions around the left and right groups of pulmonary veins to isolate them, and then each pulmonary vein is isolated individually using a segmental approach that avoids ablating the actual pulmonary vein itself.2
The HRS Consensus Statement says that for long standing persistent afib, ablation of the pulmonary vein ostia may not be enough, so if there are focal triggers outside the pulmonary veins, those should be targeted as well. Some centers target the ligament of Marshall and the back (posterior) wall of the left atrium. Whenever additional linear lesions are used, mapping or pacing must be used to ensure the linear line is complete.1
To learn more about the technology used in catheter ablations, see Catheter Ablation Technology.
1 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: Recommendations for Personnel, Policy, Procedures and Follow-Up <http://www.hrsonline.org/News/Media/press-releases/CSAblation.cfm>, Heart Rhythm Society [Internet], Copyright, 2007.
2 Calkins, Hugh, MD, Catheter Ablation for AF: Past, Present, and Future, <http://www.jafib.com/published/published.php?id=102&is=previous_issue&f=full>, Journal of Atrial Fibrillation, [Internet], Copyright, 2008.
