Monday, June 23, 2008

Intracardiac ECHO Integration With Three Dimensional Mapping: Role in AF Ablation

Presenter : Yaariv Khaykin1
Authors : Yaariv Khaykin1, MD, Allan Skanes2, MD, Zaev A. Wulffhart1, MD, Lorne Gula2, MD, Bonnie Whaley1, CVT, Richard Oosthuizen1, Catherine Seabrook1, RN, Marianne Beardsall1, RN, Atul Verma1, MD.
1 Heart Rhythm Program, Southlake Regional Health Center, Newmarket, ON, Canada
2 London Health Sciences Center

Background: Catheter ablation of atrial fibrillation (AF) is typically guided by 3D mapping. This involves point-by-point reconstruction of the 3D virtual anatomy and may be time consuming and require substantial fluoroscopy exposure. Intracardiac echocardiography (ICE) affords real time imaging of the cardiac structures during mapping and ablation.

Methods: Between February and May 2007, 15 patients (100% men, 10 with paroxysmal AF)
presenting for AF ablation were offered mapping using a novel system integrating 3D mapping and ICE. A modified ICE probe with a location sensor tracked by the mapping system was positioned in the right atrium (RA). This allowed acquisition of ECG gated images of the left atrium (LA). Endocardial contours were traced on each image and were used to generate a registered 3D map.

Results: 3D maps took a mean of 51+/-25 minutes to create, PRIOR to entering the LA and without fluoroscopy. Pulmonary veins and the esophagus were rendered in 3D. A complete map was built from a mean of 46+/-19 contours. Upon instrumentation of the left atrium, the maps were easily distorted if points collected by the mapping catheter were combined with the original map, due to deformation of the left atrial geometry by the relatively stiff ablation catheter. Pulmonary vein antrum isolation was guided by a circular mapping catheter. Since this catheter could not be visualized on the CARTO map, fluoroscopy was used to track its position and the contact between the ablation catheter and the circular mapping catheter. No substantial reduction in fluoroscopy time was thus realized, as expected. At 10+/-1 months of followup, 73% of the patients were in sinus rhythm after the initial three month blanking period. No patient suffered any complications related to the procedure or in follow-up.

Conclusions: A mapping system combining ICE and 3D electroanatomical mapping can feasibly reconstruct a 3D shell of the LA and the pulmonary veins without the need to enter the left heart. The map created is sensitive to distortion during point-by-point mapping with the standard ablation catheter.