Image integration using intracardiac ultrasound to guide catheter ablation of atrial fibrillation

Background Three-dimensional (3D) reconstruction of the left atrium (LA) can be performed using real-time intracardiac echocardiography (ICE) to facilitate image integration during atrial fibrillation (AF) ablation. Current users of this technology generally image the LA indirectly from the right atrium (RA). Objective The purpose of this study was to assess the feasibility and accuracy of image integration with placement of the ICE catheter directly in the LA to visualize the LA. Methods Thirty consecutive patients undergoing an AF ablation with the CARTO-Sound system were enrolled. A 10-Fr phased-array ICE catheter was used to obtain two-dimensional echocardiographic images of the LA; in 15 patients the ICE probe was placed in the LA, and in 15 patients it was placed only in the RA. Sequential images were obtained and merged with a preacquired computed tomography/magnetic resonance image. The accuracy of image integration was assessed by the value of the average image integration error after surface registration. Results Thirty patients (60% paroxysmal AF, LA size = 42 ± 7 mm, ejection fraction = 62% ± 10%) were studied. There was no difference in the time required to create the LA anatomic map and perform image integration with imaging from the LA versus the RA (22 ± 22 vs. 24 ± 16 minutes; P = .8). The number of ultrasound contours obtained was also similar (LA = 26 ± 17 vs. RA = 24 ± 16; P = .7). The average integration error was less with direct LA imaging (LA = 1.83 ± 0.32 vs. RA = 2.52 ± 0.58 mm; P = .0004). Conclusion Direct LA imaging with ICE is feasible and results in improved LA visualization and image integration.