Integration of 3-Dimensional Cardiac Computed Tomography Images With Real-Time Electroanatomic Mapping to Guide Catheter Ablation of Atrial Fibrillation
A 63-year-old woman was referred for catheter ablation of atrial fibrillation (AF). Two weeks before the ablation procedure, contrast-enhanced cardiac imaging was performed with a 16-slice spiral computed tomography (CT) scanner, and the planar CT images were converted to a 3D surface reconstruction of the left atrium (LA), left atrial appendage (LAA), and pulmonary veins (PVs) (Figure 1). During the electrophysiology study, a transseptal puncture was performed to enter the LA to allow mapping of the LA, LAA, and PVs with an electroanatomic mapping system (Biosense-Webster, Inc). A custom, image-guided therapy workstation was developed capable of (1) importing the 3D CT surface reconstruction, as well as electroanatomic mapping information (including real-time catheter position data) and (2) properly aligning these 2 datasets such that the catheter could be visualized and maneuvered within the high-resolution CT construct in real time to guide radiofrequency ablation (Figure 2). Accordingly, ablation lesions were placed at the periostial LA tissue to electrically isolate the PVs (Figure 3, Data Supplement Movie). Electrical isolation was confirmed by using a circular, multielectrode mapping catheter (Lasso, Biosense-Webster, Inc) for both entrance block (no electrical activity within the lesion set) and exit block (no LA capture while pacing from within the PVs).
During catheter ablation of AF, it is important to place the ablation lesions outside the PVs for both efficacy and safety reasons: to avoid leaving residual proximal cuffs of arrhythmogenic tissue and to avoid PV stenosis, respectively. Preprocedural magnetic resonance (MR) or CT imaging is often used to provide an anatomic “road map” of the LA PVs, but these static images are presently not integrated with electroanatomic mapping systems to guide the ablation procedure. This case report graphically represents the feasibility of integrating preacquired 3D CT (or MR) images with electroanatomic mapping; this image integration paradigm might improve the accuracy and safety of catheter ablation of AF.
The online-only Data Supplement, which contains a movie, is available with this article at http://www.circulationaha.org.