Merging Three-Dimensional Cardiac MRI with Electroanatomical Mapping to Guide Transendocardial Injections of Mesenchymal Stem Cells

Background: Merged CT/MRI with electroanatomical maps (EAM) have been used to guide catheters in electrophysiological interventions. We hypothesized that a novel approach, using reconstructed three-dimensional cardiac MRI of the left ventricle merged with an EAM could guide transendocardial delivery of mesenchymal stem cells (MSCs). Methods and Results: Gottingen swine (n=7) underwent LAD myocardial infarction (MI). Three months following MI and 48 hours prior to stem cell injection, gadolinium enhanced cardiac MRI was performed using a 1.5T Siemens scanner. Electroanatomical mapping of the LV was done with a NOGA XP Cardiac Navigation System with Merge software (Biosense Webster, Inc., Diamond Bar, CA). The MRI images were extracted into the NOGA XP; 3-dimensional reconstruction and segmentation of the left ventricular chamber were done using Merge software on the NOGA XP system. EAM and 3-dimensional MRI were merged using manual landmark and automated surface registration. The quality of the merge was assessed as the average distance between the MRI and the EAM, and was 3.6±1.0mm. The merged image was used to guide the transendocardial injection of 200 million MSCs in 15 sites with injections of 0.5mL each, using a NOGA MyoStar catheter. Injection sites were selected in the scar and border zone as identified by the merged unipolar voltage EAM and MRI (Figure 1). Conclusions: A three-dimensional MRI reconstruction of the LV can be integrated into a NOGA voltage map to guide transendocardial injections of stem cells; therapeutic guidance with the merged MRI/EAM combines accurate and detailed anatomical information from MRI, with functional information about scarred and viable myocardium from EAM.