Accurate understanding and visualization of the mechanisms of cardiac arrhythmias originating from a complex 3D substrate are a prerequisite for successful treatment of such disorders. Nonfluoroscopic cardiac mapping systems are designed to provide the required spatial anatomical information in combination with local electrical information. During recent years, the EnSite system, with its EnSite NavX navigation and visualization technology, and CARTO have evolved as the main representatives. EnSite Velocity is the latest released platform of the EnSite NavX technology. It represents an open system enabling 3D visualization of multiple intracardiac catheters from different manufacturers. Fusion algorithms and respiratory compensation allow for model-guided therapy with real-time nonfluoroscopic visualization of intracardiac catheters within registered 3D CT/MRI images.