A variety of cardiovascular conditions can be treated using minimally-invasive interventions. These interventions are much less stressful to the patient than conventional surgery, shortening recovery time and allowing treatment to take place even at advanced age. Examples are rhythm-disorder treatments or catheter-based valve replacement. Accurate visualization is crucial for the success of such interventions, but currently only two-dimensional visualization is possible. These complex procedures would greatly benefit from real-time three-dimensional (3D) visualization.