Real-Time MRI-Guided Cardiac Cryo-Ablation: A Feasibility Study

Real‐Time MRI Cryo‐Ablation Introduction MRI‐based ablation provides an attractive capability of seeing ablation‐related tissue changes in real time. Here we describe a real‐time MRI‐based cardiac cryo‐ablation system. Methods Studies were performed in canine model (n = 4) using MR‐compatible cryo‐ablation devices built for animal use: focal cryo‐catheter with 8 mm tip and 28 mm diameter cryo‐balloon. The main steps of MRI‐guided cardiac cryo‐ablation procedure (real‐time navigation, confirmation of tip–tissue contact, confirmation of vessel occlusion, real‐time monitoring of a freeze zone formation, and intra‐procedural assessment of lesions) were validated in a 3 Tesla clinical MRI scanner. Results The MRI compatible cryo‐devices were advanced to the right atrium (RA) and right ventricle (RV) and their position was confirmed by real‐time MRI. Specifically, contact between catheter tip and myocardium and occlusion of superior vena cava (SVC) by the balloon was visually validated. Focal cryo‐lesions were created in the RV septum. Circumferential ablation of SVC–RA junction with no gaps was achieved using the cryo‐balloon. Real‐time visualization of freeze zone formation was achieved in all studies when lesions were successfully created. The ablations and presence of collateral damage were confirmed by T1‐weighted and late gadolinium enhancement MRI and gross pathological examination. Conclusion This study confirms the feasibility of a MRI‐based cryo‐ablation system in performing cardiac ablation procedures. The system allows real‐time catheter navigation, confirmation of catheter tip–tissue contact, validation of vessel occlusion by cryo‐balloon, real‐time monitoring of a freeze zone formation, and intra‐procedural assessment of ablations including collateral damage.