A deflectable guiding catheter for real-time MRI-guided interventions

Purpose: To design a deflectable guiding catheter that omits long metallic components yet preserves mechanical properties to facilitate therapeutic interventional MRI procedures. Materials and Methods: The catheter shaft incorporated Kevlar braiding. A 180 degrees deflection was attained with a 5-cm nitinol slotted tube, a nitinol spring, and a Kevlar pull string. We tested three designs: passive, passive incorporating an inductively coupled coil, and active receiver. We characterized mechanical properties, MRI properties, RF induced heating, and in vivo performance in swine. Results: Torque and tip deflection force were satisfactory. Representative procedures included hepatic and azygos vein access, laser cardiac septostomy, and atrial septal defect crossing. Visualization was best in the active configuration, delineating profile and tip orientation. The passive configuration could be used in tandem with an active guidewire to overcome its limited conspicuity. There was no RF-induced heating in all configurations under expected use conditions in vitro and in vivo. Conclusion: Kevlar and short nitinol component substitutions preserved mechanical properties. The active design offered the best visibility and usability but reintroduced metal conductors. We describe versatile deflectable guiding catheters with a 0.057'' lumen for interventional MRI catheterization. Implementations are feasible using active, inductive, and passive visualization strategies to suit application requirements.