GUIDANCE OF RADIOFREQUENCY ENDOCARDIAL ABLATION WITH REAL-TIME 3-DIMENSIONAL MAGNETIC NAVIGATION SYSTEM

Background Ablation therapy for certain arrhythmias requires the forma tion of complex lesions based on electrical and anatomic mapping. We t ested the accuracy and reproducibility of a nonfluoroscopic mapping an d navigation (NFM) system to guide delivery of radiofrequency (RF) ene rgy in the right atrium (RA) of swine. Methods and Results The NFM sys tem uses an ultralow magnetic field to measure the real-time three-dim ensional (3D) location of the tip of the locatable catheter. While in stable contact with the endocardium, between 30 and 40 consecutive tip locations were sampled and used for the 3D reconstruction of the RA g eometry. The location of the catheter tip was presented in real time, superimposed over the RA geometry. We selected a point on the 3D recon struction and delivered RF energy to that site via the tip of the loca table catheter. The catheter was then completely withdrawn and renavig ated twice to the same point, at which RF energy was delivered again. Al autopsy, the distance between the centers of the three ablation poi nts (mean +/- SEM) was 2.3 +/- 0.5 mm (n = 27). Similarly, we used the NFM system to guide the generation of linear lesions. The measured le ngth of the linear lesions on the NFM 3D view was close to the actual lesion length measured at autopsy (correlation coefficient, .96; P = . 002; n = 6). Furthermore, the location, shape, and continuity of the l inear lesions corresponded to the autopsy findings. Conclusions We con clude that the NFM system can guide the application of the use of fluo roscopy in a highly accurate and reproducible manner.