Abstract 15798: Real Time MRI Based Atrial Cryoablation

Abstract

Introduction: Balloon cryoablation is being increasingly used for pulmonary vein isolation. Acute determination of lesion permanency cannot be ascertained directly, but is inferred by PV occlusion and acute PV isolation. We aimed to determine if direct confirmation of vessel occlusion and lesion formation could be visualized in real time in a MRI system using a novel MRI compatible cryo balloon catheter. Methods: We used a canine model (n=3) and a MRI compatible cryo balloon catheter built for animal use (Medtronic CryoCath, Montreal, Canada). The procedure was performed in a 3T (Verio, Siemens) MR scanner. The MRI compatible 28 mm cryo balloon was advanced into the right atrium (RA) via the femoral vein under MRI guidance. Gadolinium based contrast (Multihance) was injected to confirm vessel occlusion. The superior vena cava (SVC) - RA junction was frozen for 3 mins. Post ablation, late gadolinium enhancement MRI (LGE-MRI) was obtained acutely to confirm the ablation. The heart was excised to confirm the tissue changes. Results: Panel A shows the inflated balloon at the SVC ostium. Panel B shows contrast injected in the SVC confirming its occlusion. Panel C is an MR image taken during the freeze cycle. Panel D is an LGE-MRI showing enhancement along the SVC wall confirming ablation. Panel E is an axial view of the SVC confirming circumferential ablation with no apparent gaps. The ablation completeness was confirmed in pathology. Conclusion: A real time MR-based balloon cryo ablation system was implemented. It allows real time confirmation of vessel occlusion, visualization of a freeze zone and visual confirmation of tissue changes from ablation in the pre-clinical setting.