Abstract 4110: Catheter Navigation, Ablation and Lesion Visualization Using Real-Time Computer Tomography Guidance
Ablation strategies for complex arrhythmias such as atrial fibrillation or ischemic ventricular tachycardia could be facilitated by providing real-time, visual feedback about individual cardiac anatomy, exact 3D catheter position, and immediate assessment of ablation lesions. Real-time CT (RT-CT) was evaluated in seven swine (35– 40kg) using a 40/64 slice real-time CT scanner. Novel custom-made software allowed a fluoroscopy-like image projection view (“fluoroscopy mode”). Imaging modality could be instantaneously changed to 2D or 3D volume reconstruction allowing the visualization of the catheter tip in relation to the cardiac anatomy with high spatial resolution (voxel<1mm 3) (“CT mode”). Using “fluoroscopy” and “CT mode” catheter navigation was attempted from the femoral vein to the RV and retrograde-aortic to the LV. Single targeted ventricular ablation lesions and linear ablation lines were delivered at pre-defined sites. Immediately after ablation myocardium was imaged (“CT mode”) after contrast-injection to assess lesion visualization. Combination of “fluoroscopy” and “CT mode” permitted assessment of catheter curvature, orientation and exact anatomic tip location and allowed successful navigation to all four cardiac chambers. Using both imaging modes single and linear ablation lesions were successfully created at predefined RV/LV sites. Lack of radiofrequency (RF)-induced imaging artifacts allowed monitoring of the catheter tip/myocardial interface. Linear lesions had a deviation from the ideal line of 2.8±0.8mm (radiation exposure <3cGray). Ablated lesions could be successfully visualized immediately after RF delivery. The lesions appeared as rounded areas of hypoperfusion, which were well demarcated from the surrounding myocardium (43±11 vs. 88±13 Hounsfield Units, p<0.05). A small ring (<2mm) of delayed enhancement could be seen adjacent to the perfusion defect. At necropsy lesion size and transmural extent correlated well with the CT images. Novel imaging modalities for RT-CT allow successful and anatomically guided real-time navigation and ablation as well as immediate assessment of ablation lesions. This suggests a possible role of real-time CT for RF ablations.