Techniques for epicardial mapping and ablation with a miniature robotic walker

BACKGROUND: Present treatments for ventricular tachycardia have significant drawbacks. To ameliorate these drawbacks, it may be advantageous to employ an epicardial robotic walker that performs mapping and ablation with precise control of needle insertion depth. This paper examines the feasibility of such a system. METHODS: This paper describes the techniques for epicardial mapping and depth-controlled ablation with the robotic walker. The mapping technique developed for the current form of the system uses a single equivalent moving dipole (SEMD) model combined with the navigation capability of the walker. The intervention technique provides saline-enhanced radio frequency ablation, with sensing of needle penetration depth. The mapping technique was demonstrated in an artificial heart model with a simulated arrhythmia focus, followed by preliminary testing in the porcine model in vivo. The ablation technique was demonstrated in an artificial tissue model and then in chicken breast tissue ex vivo. RESULTS: The walker located targets to within 2 mm by using the SEMD mapping technique. No epicardial damage was found subsequent to the porcine trial in vivo. Needle insertion for ablation was controlled to within 2 mm of the target depth. Lesion size was repeatable, with diameter varying consistently in proportion to the volume of saline injected. CONCLUSION: The experiments demonstrated the general feasibility of the techniques for mapping and depth-controlled ablation with the robotic walker.