Cryo-Balloon Catheter Tracking in Atrial Fibrillation Ablation Procedures

Radio-frequency (RF) catheter ablation has become the standard treatment of atrial fibrillation if pharmacotherapy fails. As an alternative to traditional RF standard ablation catheters, single-shot devices have received more and more interest. One group of these devices are cryo-balloon catheters. Such catheters are designed to electrically isolate a pulmonary vein (PV) with only a few applications, ideally only one. Whereas standard radio-frequency ablation catheters operate point by point, cryo-balloon devices need to be positioned antrally to the pulmonary vein ostium before freezing. If a good seal can be achieved far enough outside of the pulmonary veins, the cryo-balloon is an effective and safe ablation device. The catheters are inserted through a transseptal sheath and are inflated using liquid nitrogen. Single-shot devices, when used successfully, promise a reduction of procedure time and Xray exposure. Single-shot devices based on ablation energies other than RF, may not carry electrodes or electromagnetic sensors. This makes it difficult to visualize them using standard EP mapping systems. As a result, fluoroscopic imaging is needed. Unfortunately, the inflated balloon may be difficult to see under X-ray. To improve this situation, we propose a new method that tracks and enhances the visualization of a cryo-balloon catheter under fluoroscopic imaging. The method involves a 2-D template of the cryo-balloon that is manually initialized and then tracks the balloon device during live X-ray imaging. To improve visualization, a 2-D ellipse is overlaid onto the fluoroscopic imaging to highlight the position of the balloon catheter. The tracking error was calculated as the distance between the tracked catheter template and the manually segmented catheter. Our method achieved 2-D tracking error of 0.60 mm ± 0.32 mm.