High-density mapping for identifying sources during ongoing atrial fibrillation

dure and integrated with real-time electroanatomical mapping (EAM) to guide cardiac mapping. However, because the MRI in this image integration paradigm is acquired pre-procedure, the cardiac anatomy during the procedure can change due to biological factors. Interventional MR imaging (iMRI) could combine real-time EAM with real-time MR imaging, thereby providing real-time anatomical information to guide catheter mapping. Methods & Results: Imaging and tracking data were acquired using a 1.5 T GE Signal CVi MRI, and electrogram information with a modified CardioLab 7000 EP recording system. Both in vitro and in vivo experiments were conducted to evaluate catheter tracking and EAM in the iMRI environment. During in vitro stuides, MR angiography (MRA) was completed on a fluid filled phantom of the aorta and left heart. These images were then semi-automatically segmented (CardEP, GE Medical) and 3D reconstructions prepared. An MR-compatible mapping catheter (see Figure; St. Jude Medical) with 3 MR tracking coils was advanced into the lumen of the phantom. During the in vivo porcine experiments, contrastenhanced MRA was completed. Following reconstruction of the imaging data, the deflectable catheter was manipulated under real-time iMRI image guidance. Real-time catheter position was updated continuously at 30 frames per second, and continuous MR imaging during tracking provided real-time update of the imaging planes. Using this methodology, mapping of the cardiac chambers to display the electrical information on the MR 3D anatomy was possible. Conclusions: This feasibility study demonstrates real-time tracking of an MR-compatible catheter to perform electroanatomical mapping within the MR environment. With further refinements, iMRI may be a clinicallyfeasible navigation paradigm.