Phillips computed tomography overlay system™. Using the system, a pre-procedural computed tomography scan of the left atrium is overlaid onto live fluoroscopic images. In this example, an endoscopic view has been chosen to show the internal surface of the left atrium. The ablation points have been tagged with yellow orbs. The coronary sinus catheter can be seen, the circular mapping catheter has been placed in the right inferior pulmonary vein, and the ablation catheter is within the right superior pulmonary vein. In this system, the rotation of the computed tomography overlay is parallel to that of the C-arm, allowing accurate catheter positioning, in any view.