Objective: The localization of an ectopic cardiac arrythmia focus is crucial during an electrophysiological ablation procudure. A non-invasive pre-procedure visualization of the cardiac electrical activity can be time saving. We aim to virtually and physically visualize the electrical, cardiac activity using a colour-coded 3D printed heart (4D heart). Material and Method: Recordings of clinical 12-lead ECG and the MRI from patients with cardiac arrythmia were used. The corresponding pictures taken from the patient’s thorax were used in order to track the position of the ECG electrodes. The Cardiac Isochrones Positioning System (CIPS) method [1] was used to calculate the cardiac electrical activity inversely, corrected for the patient specific electrode position. The MRI and the cardiac electrical activity data were used to define the colour-mapping of the 4D heart. Validation to inverse measurement was performed. Results: A single combination of attempted methods was simple enough to be practical. A realistic in-silico 3D heart from the MRI DICOM data was constructed. The 3D slicer software was used, followed by the MeshLab tool combined with Matlab. The data was stored into the VRML data format enabling the virtual visualisation of the 4D heart. Furthermore, the VRML data was used to print the 4D heart can generally be printed in any colour 3D printer. We used Stratasys (J750) and Object 500 using polyjet technology. The heat-map colour coding showed the electrical activity directly on the heart being very similar to direct measurements in the heart. Conclusion: It is possible to generate a 4D heart and visualise it virtually as well as print it in a multi-colour 3D printer. The cardiac depolarization wave is encoded into an easy-interpretable colour-coding providing the physician and the patient with an accessible tool for immediate analysis.