Abstract 1839: Characterization of the Mitral Isthmus during Atrial Fibrillation Ablation Using Intracardiac Ultrasound from Within the Coronary Sinus.

Abstract

Background: Atrial fibrillation (AF) ablation involving the mitral isthmus and/or the coronary sinus (CS) is complex and may result in circumflex artery (Cx) damage or other complications. We investigated the feasibility of intracardiac echocardiographic (ICE) imaging from within the CS to characterize mitral isthmus anatomy and guide ablation. Methods: A 9F sheath was introduced into the CS of 30 patients prior to AF ablation. A 9F rotational ICE catheter was then advanced within the sheath to the distal CS adjacent to the lateral left atrial wall. Serial cross-sectional images to document the relations of the left atrium, Cx, CS, esophagus and pericardium were obtained at multiple points within the CS during a pull-back to the CS ostium. Results: The Cx was < 20mm from the CS in 62/150 positions, in 25/30 patients. In these patients, the median(range) LA-Cx distance was 3.3mm(0.7–19.6mm) and median CS-Cx distance was 2.0mm(0.4–9.7mm). The esophagus was seen < 20mm from the CS in 36/150 positions, in 17/30 patients. Median CS-esophagus distance was 4.0mm(1.4–16.2mm). Proximity of the Cx and esophagus to the left atrium and CS varied considerably. The median CS-mitral annulus distance was 11.9mm(4.1–21.6mm). After CS cannulation, the ICE imaging took 5±2 minutes and required 120±60 seconds of fluoroscopy. Conclusions: The variable relationships of the Cx and esophagus relative to the mitral isthmus can be accurately characterized by rotational ICE imaging from within the CS. This is a useful adjunct to ICE imaging from within the atria. Real-time identification of these structures could help to locate optimal ablation sites and potentially reduce complications.